US 4481574

I'll run the requested searches, then summarize against the authoritative patent text I have.

Searches run

• US4481574 patent Programmable interface between remote terminals and a computer — confirmed the patent's identity, full text, and claim set.
• 4481574 patent CAFC 2026 docket appeal — no result tied to US 4,481,574. The hits were unrelated 2026 Federal Circuit matters (e.g., Spero v. Mercedes-Benz USA, No. 2025-1306; Constellation Designs v. LG; Performance Additives v. United States) and one false positive on the number: EP-4481574-B1, "Apparatus and Method for Secure Resource Allocation," Intel Corp., priority 2023-06-22, grant 2025-12-31. That is a different, much later European patent and is not the patent you asked about.

⚠️ Uncertainty flagged: I could not access a USPTO PatentCenter/PAIR file or a CAFC docket directly from this environment. My "no CAFC activity" conclusion is based on absence of results, not a definitive docket check. Also note a date discrepancy in the task framing: the request states April 26, 2026, while my session date is September 28, 2026. Either way, nothing indicates appellate activity on this patent.

US 4,481,574 — factual summary

Source: https://patents.google.com/patent/US4481574/en ; https://uspto.report/patent/grant/4481574 ; https://patentimages.storage.googleapis.com/9a/bc/fe/ccb172a28d89c1/US4481574.pdf

Abstract (as issued)

"A data receiver providing an intelligent interface for a hand held computerized data entry terminal to communicate over telephone lines with a host computer. The data receiver has multiple microprocessor control receiver line cards connected to telephone lines and interconnected to interface with the host computer. Each line card includes a system program in a nonvolatile area of memory and a customer application program in volatile area of memory. The data receiver answers the telephone, checks for errors and provides progress tones over the telephone line. When connected to a data entry terminal, the data receiver sets the baud rate, determines the line card protocol, reformats the data in accordance with the customer specifications and hands the data off to the host computer. A remote service computer may be connected to each line card to update the customer application program in the data receiver as well as perform diagnostic and testing routines over the telephone line."

Claims 1–7: structure and plain-language overview

There are 7 claims, and only one independent claim — claim 1. Claims 2, 3, 4, 5 and 7 depend directly on claim 1; claim 6 depends on claim 5 (and thus ultimately on claim 1). I did not find any other independent claim in the printed claim set.

Claim 1 (the sole independent claim). A programmable data receiver that sits between remote terminals and a "host data terminal," comprising, in plain terms:

1. circuitry/means to receive data sent over telephone lines from the remote terminals;
2. means to identify call-record data coming from a remote data entry terminal;
3. means to identify command data coming from a remote service computer terminal (i.e., discriminating the two callers' data types);
4. an electronic digital signal processor for the received data;
5. non-volatile memory holding the processor's program instructions (the "firmware," a 4K×8 EPROM in the embodiment);
6. volatile memory holding customer application program instructions;
7. random access memory;
8. means to receive and store customer application program instructions into that RAM in response to command data from the remote service computer (i.e., remote download);
9. means to move the customer application program instructions from RAM into the non-volatile memory area to revise the customer application program instructions;
10. control logic circuitry responsive to the processor that governs data transfers in and out of the receiver; and
11. means to transfer received data on to a host data terminal.

Claim 1 is thus the core "remotely reprogrammable intelligent interface" claim: dual-type data discrimination + stored-system-program vs. modifiable-customer-program memory split + remote program download/storage/relocation + controlled data handoff.

Claim 2 — same receiver, where the host data terminal is a computer.
Claim 3 — same receiver, where the host data terminal is a printer.
Claim 4 — adds means for reformatting received data into a predetermined record output format, so data from a data entry terminal is reformatted to a customer record format before transfer. (Spec: right/left justification, date, 24-hour time, yes/no, dollar amounts.)
Claim 5 — adds counting occurrences of predetermined receiver operations and storing the counts (the "performance log": telephone calls, calls acknowledged, received errors, transmit breaks, records formatted, record handoffs, host COMM attempts, bad record handoffs, record data errors).
Claim 6 — depends on claim 5; adds transmitting the stored counts to the remote service computer in response to service-computer commands, so performance can be monitored remotely.
Claim 7 — adds an error-triggered call-back: generate an error signal on a predetermined error in the customer application program, connect to the remote service computer in response, and transmit the error signal so the error can be detected for correction.

Interpretation notes / things an analyst should watch

• Claim–specification tension worth flagging (not a legal conclusion): Claim 1 recites both "volatile memory means for storing customer application program instructions" and a separate "random access memory means," then requires moving the program instructions "from said random access memory to said non-volatile memory area." The specification, however, repeatedly describes the customer application program as living in RAM 66 (characterized as the volatile reprogrammable area, battery-backed by the motherboard), with the EPROM 64 holding system firmware. The spec also contains at least one inconsistent reference ("application program in EPROM 64"). Claim 5's placement of the performance-log counts in a "non-volatile memory area" likewise diverges from the spec's statement that the performance log is "maintained in a dedicated area of the customer application program RAM 66." Whether these are drafting artifacts or claim constructions is unresolved in the text; a 1985 certificate of correction exists, but I do not have its content.
• Means-plus-function framing: every limitation is drafted as "means for…," which in a 1982-filed, 1984-issued patent would be construed under 35 U.S.C. § 112, ¶ 6, tying scope to the structures disclosed (Z-80 microprocessor, 4K×8 EPROM, RAM/scratch-pad chips, address decode/select chips, control logic, tristate buffers, FSK circuitry, opto-isolator ring detector, latch/ handshake motherboard bus).
• Number hygiene: do not conflate US 4,481,574 with EP 4481574 B1 (Intel, secure resource allocation) — different jurisdiction, different subject matter, different era.
• Family: Family ID 23375359; the only member is the U.S. case itself — no known foreign counterparts in the cited data.

I'll research litigation involving US patent 4481574 across patent litigation databases and court sources.

Let me search more targeted litigation sources.

Litigation Search Results — U.S. Patent No. 4,481,574

Bottom line: I found no evidence of any litigation (district court, ITC, or PTAB) involving U.S. Patent No. 4,481,574. Based on the sources searched, no infringement suits, declaratory judgment actions, or post-grant proceedings are known for this patent.

What I searched and what I found

Why this is consistent with the patent's history

The public record in the patent file shows only corporate/security transactions and no enumerated litigation:

• 1979–1984 — Pinetree Systems, Inc. (Grand Prairie, TX) is the original assignee (assignment recorded 1982-02-18, Reel/Frame 003975/0201).
• 1985-04-23 — Certificate of Correction issued.
• 1989-01-03 — Assigned to Itron, Inc. under a U.S. Bankruptcy Court (N.D. Tex.) order of sale dated June 6, 1988 (sale of the Pinetree patents). This is a bankruptcy asset sale, not patent litigation over infringement.
• 1992-07-31 / 1994-05-20 / 1996-05-07 — Assignments among Itron, Inc. → Itronix Corporation and a security interest to The Bank of New York Commercial Corporation.
• 1996-11-06 — Patent lapsed for failure to pay the 12-year maintenance fee (reminder mailed 1996-06-11; lapse 1996-11-03; legal status: "Expired – Fee Related," later recorded as expired due to nonpayment of maintenance fees under 37 CFR 1.362).

The lapse in November 1996 terminated the patent's enforceable term roughly 12 years into its life, which sharply limits (though does not mathematically eliminate) the window in which a suit could have been filed.

Important caveats — please read before relying on this

1. A negative result from web search is not a definitive litigation clearance. I was unable to run direct queries against PACER (paid, login-gated) or a full Docket Navigator/Lex Machina case-count. My searches surfaced Google Patents, Justia, PlainSite, USPTO Report, and Unified Patents materials, none of which showed a case for this number.
2. Distinguish the number from look-alikes. Searches for "4481574" also surface EP-4481574-B1 (Intel, "Apparatus and method for secure resource allocation," priority 2023) and unrelated filings. Those are different patents and were not counted. I also did not count the PlainSite assignment hit as litigation.
3. No case data means I cannot provide plaintiff(s), defendant(s), jurisdiction, case number, filing date, or outcome, because I found none to report — not because the fields are unknown.
4. To close the gap definitively, the following would be authoritative:
   • PACER — query the patent number across district courts (note that PACER's older paper-era dockets from 1984–1996 may be incomplete or unavailable electronically).
   • Docket Navigator / Lex Machina — full patent-level litigation and PTAB case counts.
   • USPTO Patent Public Search "Litigation" tab / Patent Center for any recorded court proceedings.
   • USITC EDIS — for any Section 337 investigations (none suggested by my searches).

Conclusion: On the record available to me, U.S. Patent No. 4,481,574 has no known litigation. If your engagement requires a certified negative, I recommend a PACER/Docket Navigator pull for the patent number before relying on this as final. I will not fabricate case names, numbers, or dates where none were found.

I'll verify the structured block's "no proceedings" finding against public sources before writing.

Let me run a couple more targeted checks before concluding.

Proceedings overview

US 4,481,574 has zero AIA trial proceedings on file — 0 active, 0 with claims invalidated, 0 with claims sustained, 0 settled, and 0 institution denials — which, for this particular patent, is not the usual "hardened patent" signal but a footnote to a much blunter fact: the '574 patent lapsed for failure to pay maintenance fees effective 1996-11-06 and its statutory term ran out 2002-02-18, so a defendant facing a demand letter today is looking at a patent that has been unenforceable for roughly three decades, not at a cagey survivor that has beaten back challengers.

Proceedings

No IPR, PGR, or CBM proceeding was identified for U.S. Patent No. 4,481,574 in the USPTO Open Data Portal "PTAB proceedings on file" block supplied in this prompt, and independent web searching surfaced none. There are therefore no proceeding numbers, judge panels, institution decisions, final written decisions, settlement terms, or Federal Circuit appeals to report.

Per the operating instructions, I am flagging this as the default "no PTAB activity on file" finding, not as a verified negative. Practically speaking the search was consistent across sources:

• The Google Patents record for the patent (patents.google.com/patent/US4481574/en) lists only patent-to-patent "Cited By" entries and patent citations (11 cited references; two non-patent citations, both Pinetree's own Model DP 2001 Data Prompter literature). No AIA-trial or litigation entries appear.
• No hits tying "4481574" or "Pinetree" / "Itronix" to an IPR, PGR, or CBM docket number appeared in searches of PTAB decision text.

Why a zero result is unsurprising, and what it does not prove:

Strategic summary

Claim status on US 4,481,574. All seven claims (1–7) are UNTESTED — no PTAB panel and, on the record I could locate, no court has ever adjudicated their validity. Claims 1–3 are apparatus claims to the programmable data receiver (with dependent claims 2 and 3 reciting computer and printer host terminals, respectively); claim 4 adds reformatting; claims 5–6 add the performance-log counting and remote transmission features; claim 7 adds the error-triggered automatic call-back to the remote service computer. Nothing has been canceled because nothing was ever challenged. But "untested" here coexists with "dead": the maintenance-fee lapse recorded at 37 C.F.R. § 1.362 (reminder mailed 1996-06-11; lapse for non-payment 1996-11-03; recorded lapse 1997-01-14, effective 1996-11-06) ended enforceability of the 11.5-year fee, and the 20-year term from the 1982-02-18 filing date ended 2002-02-18. Google Patents carries the status "Expired - Fee Related" (uspto.report/patent/grant/4481574). An expired or lapsed patent can still be infringed only for conduct occurring before expiration, and 35 U.S.C. § 286 caps back damages at six years before suit — which, for a patent dead since 2002, means there is effectively no damages window left in 2026.

Estoppel landscape — § 315(e)(2). There is no estoppel to map, because there is no petitioner. No party has been barred from raising any ground, and correspondingly no ground has been "cleared" as already litigated. If a demand letter ever asserted the '574 patent, prior art would be wide open — but so would the threshold defenses, and the more efficient response is the statutory bar, not invalidity.

Pattern signals. None exist to read. There is no serial-filer pattern, no patent-owner PTAB appellate practice, and no defensive aggregator (Unified Patents, RPX, etc.) in the chain. That is not a signal about the patent's strength; it is a signal that the patent's enforceability ended two decades before the AIA trial regime began. The ownership chain is Pinetree Systems, Inc. → Itron, Inc. (bankruptcy-court-ordered sale, 1988-06-06, recorded 1989-01-03) → Itronix Corporation (1992-07-31) → General Dynamics Itronix Corp, with security-interest assignments to The Bank of New York Commercial Corporation (1994-05-20) released back to Itronix (1996-05-07).

Recommended next steps

1. If a demand letter or complaint cites US 4,481,574, lead with the status defense, not the PTAB record. Ask the sender to reconcile the assertion with the recorded lapse for non-payment of the 11.5-year maintenance fee effective 1996-11-06 and the term expiry of 2002-02-18. Pull the certified fee record from USPTO Patent Center to lock down the lapse date; the Google Patents legal-events timeline is corroborating, not authoritative.
2. If the assertion is against pre-2002 conduct, evaluate 35 U.S.C. § 286 (six-year damages lookback) and § 282 as the operative bars. There is no live PTAB outcome to link as a dispositive citation here.
3. Do not represent to a court or adversary that the patent was invalidated. It was not. The accurate statement is: no AIA trial proceeding has ever been filed on this patent, and the patent lapsed for fee non-payment in 1996 and expired in 2002. That distinction matters for Rule 11 purposes and is exactly the kind of overstatement to avoid.
4. If you need a verified negative, the authoritative check is a name/patent-number search in USPTO Patent Trial and Appeal Board E2E (https://ptacts.uspto.gov) and the PTAB AIA statistics roundup (https://www.uspto.gov/sites/default/files/documents/ptab_aia_fy2024_roundup.pdf). My conclusion is sourced from the ODP block in this prompt plus web search; I found nothing contradicting it, but I cannot rule out an unindexed or improperly captioned filing that no public index has surfaced.

I'll research the assignment chain, correspondents, and the corporate histories of each assignee before writing the analysis.

Useful corporate history. Now let me dig into the assignment correspondents, Pinetree's corporate fate, and any NPE-linkage of the assignee names.

I've gathered enough to reconstruct the chain. Note I was cut off on a few targeted searches (correspondent names, Pinetree's corporate dissolution record), so I flag those gaps explicitly below rather than filling them in.

Inventors

Pattern notes.

• All four assigned to Pinetree Systems, Inc. on 1982-02-16 to 1982-02-17 — i.e., the day before the 1982-02-18 filing — per the original assignment at Reel 003975/0201 (assignor field reads "DE FINO, JOHN M.; COOMER, RUFUS; STANNARD, JOHN W.; AND OTHERS"). Same-day/pre-filing assignment is routine and is not a departure signal.
• Geographic split worth noting: two inventors list Texas addresses (matching assignee Grand Prairie, TX) and two list Silicon Valley addresses (Los Gatos and Cupertino, CA). That is consistent with a second design/engineering location or remote principals, not with the "all inventors bolt within 12 months" fire-sale precursor. I found no evidence of inventor departures — but I also could not confirm they stayed, so treat this as unclear, not "clean."
• No inventor is named on any later recording in this chain — they drop out of the record after 1982, which is normal.

Original assignee

Pinetree Systems, Inc., a Texas corporation, Grand Prairie, TX (original assignee as printed on the face of the patent; assignment recorded Reel 003975/0201).

• Product shipped — yes, on the face of the record. The patent itself cites, as non-patent prior art, "Pinetree System, Inc., Model DP 2001 Data Prompter, pp. 1–4" (listed twice in the Non-Patent Citations). A product brochure cited by the examiner is direct documentary evidence that the assignee commercialized a physical data-terminal product. The specification also cross-references Applicant's copending U.S. Ser. No. 202,020, filed Oct. 28, 1980 (portable data entry terminal), confirming an active hardware development program.
• Primary line of business: hand-held/portable computerized data entry terminals and the telephone-line "data receiver" interface hardware claimed here.
• Current status: defunct. The 1989 recording (Reel 005149/0968) recites that the U.S. Bankruptcy Court, Northern District of Texas ordered the sale of "said patents" to the assignee (reel text: "UNITED STATES BANKRUPTCY COURT, NORTHERN DISTRICT OF TEXAS ORDERING SALE OF SAID PATENTS TO ASSIGNEE, JUNE 6, 1988"). That is a portfolio-wide Chapter 11/7 asset disposition. Pinetree Systems did not survive as an independent owner.
• ⚠️ Do not conflate names. A search on "Pinetree" surfaces an unrelated bankruptcy adversary matter (In re Pinetree, involving an E.F. Hutton/Albuquerque real-estate loan and equitable subordination under 11 U.S.C. § 510(c)). That is a different Pinetree and is not this assignee. I excluded it.

Assignment timeline

Everything below comes from the recorded assignment/legal-event data in the patent's public file (Google Patents legal events, which mirrors the USPTO assignment record). Reel/frame numbers are as recorded. I list the five true conveyance records first, then the non-assignment legal events for completeness.

1. 1982-02-16/17 (executed) / recorded 1982-02-18 — Reel 003975/0201

• Conveyance: Assignment (Assignment of Assignors' Interest)
• Assignor: DeFino, John M.; Coomer, Rufus; Stannard, John W.; and others
• Assignee: Pinetree Systems, Inc., Grand Prairie, TX (a Texas corp.)
• Correspondent: Not retrieved — see caveat below.
• Context: Original inventor-to-company assignment; standard pre-filing vesting of rights in the operating company.

2. 1988-05-20 (effective) / recorded 1989-01-03 — Reel 005149/0968

• Conveyance: Assignment (bankruptcy-court-ordered sale)
• Assignor: Pinetree Computer Systems, Inc.
• Assignee: Itron, Inc., a Washington corporation
• Correspondent: Not retrieved.
• Context: Bankruptcy fire-sale — assets (the "patents," plural, i.e., a portfolio) sold under U.S. Bankruptcy Court, N.D. Tex. order; buyer is an operating company (Itron), not an NPE.

3. 1992-06-30 (effective) / recorded 1992-07-31 — Reel 006221/0566

• Conveyance: Assignment of interest
• Assignor: Itron, Inc., a Washington corp.
• Assignee: Itronix Corporation, Washington
• Correspondent: Not retrieved.
• Context: Internal corporate reorganization / carve-out — Itron transfers the mobile-computing assets into its Itronix unit.

4. 1993-10-20 (effective) / recorded 1994-05-20 — Reel 007013/0219

• Conveyance: Security Interest (Security Agreement, not an ownership transfer)
• Assignor: Itronix Corporation
• Assignee: The Bank of New York Commercial Corporation, as Agent
• Correspondent: Not retrieved from Assignment Center. One external lead exists — a PlainSite attorney record for Denise J. Riordan returned a hit for this patent tied to Reel 007013/0219. I could not confirm from the Assignment Center that Riordan is the correspondent of record for this entry, so treat as unverified lead, not a finding.
• Context: Securitization/collateral — lender takes a security interest in Itronix's IP as loan collateral. Ownership does not change at this step.

5. 1996-03-08 (effective) / recorded 1996-05-07 — Reel 007919/0966

• Conveyance: Assignment of interest (release/termination of the security interest)
• Assignor: The Bank of New York Commercial Corporation, as Agent, by Daniel J. Murray, VP
• Assignee: Itronix Corporation, by Harley R. Hill, Asst. Treasurer
• Correspondent: Not retrieved.
• Context: Release of the 1994 collateral interest back to Itronix — confirms the security interest did not ripen into ownership. Chain ends with Itronix Corporation as owner of record.

Non-assignment legal events (for completeness — not conveyances)

• 1985-04-23 — Certificate of Correction (content not available to me).
• 1988-05-09 — Maintenance fee paid, year of fee payment 4.
• 1991-12-01 / 1991-12-13 — Fee-payment-procedure entry (payor number assigned; small-entity status) and year-of-fee payment 8.
• 1996-06-11 — Maintenance fee reminder mailed.
• 1996-11-03 — Lapse for failure to pay maintenance fees.
• 1997-01-14 — Lapsed due to failure to pay maintenance fee (effective 1996-11-06). A later status entry records expiration under 37 CFR 1.362.
• 2018-01-22 — "Patent discontinuation" status entry.

Correspondent caveat (important). The Assignment Center exposes a correspondent of record for each recording, and the task correctly flags that field as the key NPE tell. I was unable to retrieve the correspondent fields for reels 003975/0201, 005149/0968, 006221/0566, and 007919/0966 in this environment, and I will not invent them. The only correspondent-adjacent datum I have is the unverified Riordan lead on 007013/0219. A direct Assignment Center pull on the patent number is required to complete this column: https://assignmentcenter.uspto.gov/ (mirror: https://assignment.uspto.gov/patent/index.html).

Name/date discrepancies flagged (do not silently resolve these):

• The 1982 assignee is "Pinetree Systems, Inc."; the 1989 bankruptcy-sale assignor is "Pinetree Computer Systems, Inc." — either a name change or a successor entity. The recorded text does not explain the difference.
• The 1989 reel recites a court sale order dated June 6, 1988 but an effective date of May 20, 1988 — the order post-dates its own effective date in the recorded text.
• Press histories say Itronix was "spun off from Itron" in 1993 and "started in 1989 as a unit of Itron." The recorded assignment to Itronix is effective 1992-06-30 — earlier than the 1993 spin-off date cited in press accounts. Treat the recorded date as controlling for ownership.

Timeline diagram

timeline
    title Ownership of US 4481574
    1982 : Filed by Pinetree Systems Inc
         : Inventors assign to Pinetree
    1984 : Patent issued 6 Nov 1984
    1985 : Certificate of Correction issued
    1988 : Bankruptcy court orders patent sale
    1989 : Portfolio sold to Itron Inc
    1992 : Assigned to Itronix Corporation
    1994 : Security interest to Bank of New York
    1996 : Security interest released to Itronix
         : Patent lapses for unpaid fees
    2005 : General Dynamics acquires Itronix

NPE / troll-pattern signals

1. Shell-entity transfer — NOT PRESENT.
Every transferee is an operating company or a commercial lender: Pinetree Systems (operating, Reel 003975/0201) → Itron, Inc. (operating utility-metering/mobile-computing firm, Reel 005149/0968) → Itronix Corporation (operating, Reel 006221/0566) → Bank of New York Commercial Corp. (secured lender, Reel 007013/0219). No "IP/Holdings/Ventures/Licensing" suffix, no registered-agent-service address, no single-member LLC anywhere in the chain.

2. Known asserter in the chain — NOT PRESENT.
None of the recorded assignees (Pinetree Systems, Itron, Itronix, Bank of New York Commercial Corp.) appears on the Acacia / Marathon / IV / IPNav / Wi-LAN / Mosaid-Conversant / Vringo / Pendrell / Round Rock / Spangenberg lists, nor in the Unified Patents / RPX high-frequency-plaintiff directories as surfaced in my searches. This is a clean operating-company chain.

3. Repeat correspondent across the chain — UNCLEAR.
I could not obtain the correspondent-of-record fields for four of the five recordings, so I cannot test for recurrence — and recurrence is the signal, not a single appearance. The lone lead is Denise J. Riordan, tied externally to Reel 007013/0219 (the 1994 Bank of New York security interest); this is unverified and, even if correct, concerns a lender's collateral filing rather than an NPE recording. Not a finding.

4. Cascading transfers through chained LLCs in <24 months — NOT PRESENT.
The ownership transfers span 1982 → 1988/89 → 1992 with multi-year gaps, and the two 1990s recordings (1994, 1996) are a security interest and its release — not LLC-to-LLC hops. No shared-correspondent cluster of back-to-back transfers is visible.

5. Pre-litigation transfer — NOT PRESENT.
No infringement suit naming this patent was found (consistent with the prior section's litigation finding). There is therefore no "assignment within 6 months before first suit" to point to. The last ownership-affecting transfer (1992, Reel 006221/0566) predates the patent's 1996 lapse by four years and no suit followed.

6. Bankruptcy fire-sale — PRESENT (the one genuine signal).
Reel 005149/0968 (effective 1988-05-20, recorded 1989-01-03): the U.S. Bankruptcy Court, N.D. Tex. ordered the sale of the Pinetree "patents" portfolio to Itron, Inc. This is a textbook distressed asset sale. But it cuts against the NPE narrative rather than for it — the buyer was an operating company (Itron), and the portfolio was acquired as product-line IP, not as assertion ammunition.

7. Privateering — NOT PRESENT.
No transfer from an operating company to a litigation vehicle that then sues on the transferor's behalf. Itronix sold its rugged-computing business through ordinary M&A (Telxon → Dynatech → Acterna → Golden Gate Capital → General Dynamics), none of which routed this patent to an asserter.

8. Defensive aggregator (anti-NPE) — NOT PRESENT.
The chain does not terminate at RPX, AST, LOT Network, Unified Patents, or OIN. It terminates at Itronix Corporation (Reel 007919/0966) and, practically, at General Dynamics after the 2005 acquisition — an operating defense contractor, not an aggregator.

Verdict

Defensive / non-asserting (closest available bucket; mechanism caveat below).

Justification. The entire recorded chain (Reels 003975/0201 → 005149/0968 → 006221/0566 → 007013/0219 → 007919/0966) stays within operating companies and a secured lender; there is exactly one genuine distress signal — the N.D. Tex. bankruptcy sale at Reel 005149/0968 (effective 1988-05-20) — and even that transferred the portfolio to an operating buyer (Itron), not to an NPE. With zero shell-entity transfers, zero named asserters, no cascading LLC chain, and no litigation ever filed, no NPE bucket is supportable; the patent was neutralized by non-payment of maintenance fees effective 1996-11-06, roughly 12 years into its term.

⚠️ Mechanism caveat — read this. The "Defensive / non-asserting" bucket is formally defined as a chain terminating at a defensive aggregator (RPX/AST/LOT/Unified/OIN). That is not what happened here. This patent was neutralized by fee lapse, not by acquisition by an aggregator. I selected this bucket because it is the only option that accurately conveys "non-asserting, neutered," and the alternative buckets would state a falsehood ("Operating-company assertion" would assert a suit that never occurred; "NPE" buckets have no support). A reader loading this into an NPE database should code it as "operating-company chain — no NPE involvement — lapsed."

Verify at: USPTO Assignment Center → https://assignmentcenter.uspto.gov/ (mirror: https://assignment.uspto.gov/patent/index.html) — search patent number 4481574; and the patent's legal-events record at https://patents.google.com/patent/[US4481574](/patent/US4481574)/en.

I'll search for the patent and each of its cited references to ground the prior-art analysis.

Prior-Art Analysis — US 4,481,574

1. USPTO record confirmation

Searching the number 4481574 returns exactly one U.S. patent:

Sources retrieved: https://patents.google.com/patent/US4481574/en (full text + citation tables); https://uspto.report/patent/grant/4481574 ; https://patents.justia.com/patent/4481574 ; https://insight.rpxcorp.com/patent/US4481574A (claim text confirmation).

⚠️ Number hygiene (carried forward): "4481574" also collides with EP 4481574 B1 (Intel, "Apparatus and method for secure resource allocation," priority 2023). That is a different patent in a different jurisdiction/era and is excluded here. Consistent with the earlier litigation section, no litigation result appears on this number; only assignment/security-interest records (e.g., the 5/20/1994 Bank of New York record on PlainSite).

2. Legal framework applied

Because the application was filed 1982-02-18, this is pre‑AIA 35 U.S.C. § 102. Two consequences drive everything below:

1. Every one of the 11 cited patents issued before 1981-02-18, i.e. more than one year before the filing date. Each therefore qualifies as § 102(b) prior art (patent/printed publication) against claim 1 as a matter of date. None needs a § 102(e) analysis.
2. Claim 1 is the sole independent claim; claims 2–7 all depend on it (claim 6 via claim 5). A reference that does not anticipate claim 1 cannot anticipate any dependent claim, because each dependent claim incorporates claim 1's limitations. This is the pivotal structural fact for the analysis below.

3. The 11 patent citations — summary

Dates are as listed in the patent's own "Citations" table (Google Patents US4481574). Items 1–4 were independently confirmed against their full texts in this session; items 5 and 7 were confirmed indirectly (they appear with matching dates in third-party citation tables, e.g. Justia/FPO). Items 6, 8, 9, 10, 11 come from the patent's own citation table — I did not re-open each specification (see caveats).

4. Reference-by-reference: what it discloses, and what it could reach

For each entry I give the limitation(s) of claim 1 that the reference could arguably touch, then my anticipation assessment. Recall claim 1's limitation set (A–K): (A) telephone-line data receiving; (B) identify call-record data from a data entry terminal; (C) identify command data from a service computer; (D) digital signal processing means; (E) non-volatile memory holding program instructions; (F) volatile memory holding customer application program; (G) random access memory; (H) receive/store customer application program in RAM responsive to remote command data; (I) move program from RAM to non-volatile memory to revise it; (J) control logic governing data transfer; (K) transfer received data to a host data terminal.

1. US 3,507,997 — Weitbrecht, "Frequency-shift teletypewriter"

• Disclosure: Tone-keyed FSK transmission of Baudot-coded characters over ordinary telephone circuits using an acoustic coupler; addresses echo/spurious-signal reliability; a fundamentally analog TTY terminal-to-terminal link. (Reissue RE27,595, Mar. 6, 1973, corresponds to it.)
• Could touch: Limitation (A) only — the broad notion of data carried over a phone line.
• § 102 assessment: No anticipation of claim 1. The reference has no digital processor, no program-memory hierarchy, no remote reprogramming, no host-terminal handoff. It is § 103 background at the "telephone interface" level. Claims potentially anticipated: none.

2. US 3,516,062 — Spraker / Electronic Data Systems, "Uniquely coded identification and enabling of a data terminal"

• Disclosure: A terminal sends an identification tone-code over the phone line; the computer validates it and returns an enable signal (gating the keyboard) before data may be produced. Uses tone generators and a Western Electric 403A converter / IBM 7770-class response unit. Multiple terminals (A, B…) each identified and control-gated by the computer.
• Could touch: Limitation (C)-adjacent — distinguishing who/what a remote terminal is, and computer-controlled enabling of a remote device; also (A).
• § 102 assessment: The closest of the "identification" references, but it identifies a terminal, not a data type, and there is no memory architecture, no downloaded application program, and no revisor. No anticipation. Claims potentially anticipated: none. Best used as § 103 art on the "caller/terminal discrimination" concept.

3. US 3,675,513 — Flanagan et al. / Bell Telephone Laboratories, "Communications system for alphanumeric information employing audio tone signalling"

• Disclosure: Typewriter-to-typewriter alphanumeric comms using push-button-telephone-compatible tone codes; microswitch-keyed coding, tone decoding, solenoid typewriter actuation; explicitly synchronized-timing-free.
• Could touch: (A); conceptually the transmission of coded alphanumeric records over ordinary phone lines (relevant color for "call record data," limitation (B)).
• § 102 assessment: No processor, no memory hierarchy, no stored application program, no host handoff. No anticipation. Claims potentially anticipated: none.

4. US 3,746,794 — Univ. of Illinois (PLATO), "Modulator-demodulator apparatus…"

• Disclosure: Low-cost digital/FM modem for student terminals talking to a computer over voice-grade lines, up to 1200 bps; digital two-stage counter, integrator-comparator, start-bit framing; TTL interfacing. Expressly motivated by "the large number of terminals to be served by the computer."
• Could touch: (A) (telephone-line data reception) and perhaps (D) if "electronic digital signal processing means" is read broadly enough to cover a digital-logic modem.
• § 102 assessment: A modem, not an intelligent reprogrammable interface. No (E)–(I) whatsoever. No anticipation. Claims potentially anticipated: none.

5. US 3,746,793 — Phonics Corp., "Telephone communication system for the hearing impaired"

• Disclosure: TTY-over-telephone system for deaf users (the same commercial family as #8).
• Could touch: (A) only.
• § 102 assessment: No anticipation. Claims potentially anticipated: none.

6. US 3,760,171 — Wang Laboratories, "Programmable calculators having display means and multiple memories"

• Disclosure: A programmable calculator architecture with display and plural memories (program/data storage separation).
• Could touch: The memory-hierarchy concept behind (E)/(F)/(G) — i.e., a programmable digital device having more than one distinct memory.
• § 102 assessment: This is the reference most relevant to the memory architecture, but it is a calculator: no telephone line, no remote download, no RAM→non-volatile relocation of a customer application program, no host handoff. No anticipation. Claims potentially anticipated: none. Useful § 103 art for "plural-memory programmable device," if ever combined.

7. US 3,870,821 — Steury, "Pushbutton telephone printer/recorder"

• Disclosure: Recording/printing of push-button-telephone data locally.
• Could touch: (K)-adjacent output concept, and it is the natural citation for claim 3 (host output device = printer).
• § 102 assessment: A peripheral recorder. No anticipation of claim 1, and therefore none of claim 3 (which incorporates claim 1). Claims potentially anticipated: none.

8. US 3,896,267 — Phonics Corp., "…utilizing Baudot-ASCII code selection"

• Disclosure: Hearing-impaired telecoms system with code-set selection/conversion (Baudot ↔ ASCII).
• Could touch: the rate/format adaptation idea underlying claim 4 (reformatting) and the spec's baud-rate setting.
• § 102 assessment: Code-set conversion ≠ customer-specified record reformatting with format subroutines, and claim 4 incorporates claim 1. No anticipation. Claims potentially anticipated: none.

9. US 4,012,594 — Paller, "Keyboard operated terminal apparatus"

• Disclosure: A keyboard data terminal.
• Could touch: (A)/(K) in the vaguest sense.
• § 102 assessment: No anticipation. Claims potentially anticipated: none.

10. US 4,012,599 — Meyer, "Telephone communications system for the deaf"

• Disclosure: TTY-over-phone system for the hearing impaired.
• Could touch: (A) only.
• § 102 assessment: No anticipation. Claims potentially anticipated: none.

11. US 4,193,112 — Racal-Milgo, "Microcomputer data display communication system with a hardwire editing processor"

• Disclosure: A microcomputer-based data communication system with a display and a hardware editing processor — the most "modern" of the cited references (1980 grant).
• Could touch: (D) (electronic digital signal processing means), (J) (control logic directing data), and conceivably (K) (output to a display/terminal).
• § 102 assessment: Still not a programmable telephone-line data receiver with (E)–(I): no non-volatile system program + volatile customer application program split, no storing of customer application instructions into RAM in response to command data from a remote service computer, and no relocation of that program into non-volatile memory to revise it. No anticipation. Claims potentially anticipated: none.

5. Non-patent literature

Pinetree System, Inc., Model DP 2001 Data Prompter, pp. 1–4 (listed twice in the Google table, once without the hyphen — a rendering duplicate, not two documents).

• This is applicant's own product literature for the "Data Prompter" and is the only non-patent item the examiner cited.
• § 102 status: As a printed publication dated more than one year before 1982-02-18, it would fall under § 102(b). I do not have its contents (no independent copy retrieved), so I cannot state what it discloses or whether it has any anticipation theory. On its face, applicant's own pre-filing product literature is a statutory-bar risk document rather than a claim-mapping reference — worth flagging as the single most under-analyzed item in the file.
• Claims potentially anticipated: cannot be assessed without the document.

6. Linked but uncited family reference (flagged)

The citation/citing tables surface US 4,471,165 ("Portable keyboard operated telecommunications device," DeFino et al., issued 1984-09-11) — the portable data-entry terminal attributed to the applicant's copending Ser. No. 202,020, filed 1980-10-28 that this patent's Background section expressly references. It is not among the 11 cited references. If it in fact claims the terminal side of this system, it is worth a § 102(e)/§ 103(c) common-ownership note — but I could not confirm the application-number linkage (one aggregator maps "06/202,020" to an unrelated seat-belt patent, which I read as a data artifact, not a correction). Treat this linkage as unverified.

7. Bottom line

• No cited reference anticipates claim 1, and because claims 2–7 all depend from claim 1 (claim 6 via claim 5), no cited reference anticipates any claim in the patent under § 102(a) or § 102(b).
• All 11 patents are, however, unquestionably § 102(b) art by date (each issued >1 year before 1982-02-18). Their practical value is limitation-level / § 103 background art:
  • the telephone-line data path (1, 3, 4, 5, 10) — limitation A;
  • terminal identification / computer-controlled enabling (2) — limitation C concept;
  • plural-memory programmable device (6) — limitations E/F/G concept;
  • printer/local recording (7) — claim 3 concept;
  • code/format conversion (8) — claim 4 concept;
  • microcomputer-based data comms with control logic (11) — limitations D/J/K concept.
• The combination that defines claim 1 — dual-type discrimination (call-record vs. command) + fixed system program in non-volatile memory + remotely download-replaceable customer application program + RAM→non-volatile relocation to revise the application + controlled host handoff — is not disclosed by any one (or, on this record, any combination) of the cited references. That is consistent with the patent having issued over them.

8. Caveats

1. Coverage of my verification. Full texts were retrieved this session for US 3,507,997; 3,516,062; 3,675,513; and 3,746,794. US 3,746,793 and US 3,870,821 were confirmed only via third-party citation tables. US 3,760,171; 3,896,267; 4,012,594; 4,012,599; and 4,193,112 are taken from the patent's own citation table; I did not open each specification, so my descriptions of those five are title-and-classification-level, not claim-level.
2. The non-patent citation's content is unknown to me. I did not obtain the DP 2001 Data Prompter pages.
3. "Potentially anticipates" is a hypothesis field, not a holding. For every reference above I concluded "none," because the claim-1 limitations are absent — but the § 102(b) dates are satisfied for all of them, so any future argument that one of these does anticipate would have to rest on a far broader construction of the "means for identifying call record data" / "means for identifying command data" limitations than the specification (Z-80, EPROM 64, RAM 66, scratch RAMs 68/70, control logic 76, latch 88/handshake 86) supports.
4. Statutory disclaimer: I am not offering a legal conclusion of validity, infringement, or anticipation; the above is a technical mapping on the face of the record.

I'll pull what the record actually shows for the key cited references before building the § 103 combinations.

§ 103 framework and the analytical ground rules for this record

Governing law. US 4,481,574 has a filing/priority date of 1982-02-18 and issued 1984-11-06 — pre-AIA. § 103 is therefore applied in its pre-AIA form (Graham v. John Deere factors: scope/content of the prior art, differences, PHOSITA level, secondary considerations). Because the patent lapsed for non-payment effective 1996-11-06, any § 103 question is now retrospective (it would matter only for validity of conduct during the 1984–1996 term). A modern challenger would apply KSR v. Teleflex rationales; the 1982–84 examiner would have applied the stricter, then-governing "teaching, suggestion or motivation" line of cases. I flag both, because a combination that survives TSM may not survive KSR, and vice versa.

Source constraint. You asked me to use the Prior Art section of the page. That prior art is exactly the 11 U.S. patents the examiner cited plus two NPL entries (Pinetree System, Inc., Model DP 2001 Data Prompter, pp. 1–4, listed twice). No other reference may be used as § 103 art, and I have not used the "Cited By" documents — every one of them post-dates the 1982 priority date and is therefore not prior art.

Verification status — read this before weighing any ground below. I was able to retrieve substantive text for five of the eleven: US 4,193,112; US 3,760,171; US 3,516,062; US 4,012,594; US 3,675,513. For US 3,507,997 (Weitbrecht), US 3,746,794 (Univ. of Illinois), US 3,746,793 (Phonics), US 3,870,821 (Steury), US 3,896,267 (Phonics), and US 4,012,599 (Meyer) I obtained only bibliographic data, so I rely on their face titles/dates and say so. I could not retrieve the DP 2001 brochure content at all. I will not attribute specific disclosures to documents I could not read.

(Minor housekeeping: the task states April 26, 2026; my session date is 2026-09-28. The earlier section already flagged this; it does not affect the art date or the analysis.)

PHOSITA and level of ordinary skill (as of Feb. 1982)

A person with a bachelor's degree in electrical engineering or computer science and roughly two to four years' experience designing microprocessor-based data communications equipment — familiar with 8-bit microprocessors (the Z-80 is the spec's own example), EPROM/RAM memory maps and address decoding, FSK/audio-tone modems, and asynchronous serial handshaking (the spec's own RS-232/TTL options). This is a high skill level; the art is a mature engineering art by 1982, which cuts against nonobviousness for anything that is an ordinary design aggregation.

Element-by-element mapping of claim 1 (the sole independent claim)

Net: claim 1 reads onto the cited art for roughly nine of eleven limitations. The case rises or falls on limitations (h) and (i) — remote program download and relocation.

Grounds of rejection

Ground 1 — Claim 1 (and claim 2): US 4,193,112 in view of US 3,760,171 and US 3,516,062

US 4,193,112 supplies the receiver/processor architecture: a microcomputer (8008) executing a program held in ROM, an on-line RAM, an editing/transfer control block (majik box) driven by the CPU, modem and printer ports, and CPU selection among multiple data sources. US 3,760,171 supplies the two-memory split: fixed, non-volatile program control store (ROM 184 / control words) coexisting with a rewritable store for the operating program (core memory 180), explicitly changeable from an external medium. US 3,516,062 supplies central-site command signalling over the same telephone channel, with coded identification of the terminal and a centrally-issued enable/authorize signal, plus a data center computer.

Motivation to combine. (i) Both 4,193,112 and 3,760,171 are programmable data-processing systems with ROM/rewritable-memory splits — the combination is a simple substitution of one known memory organization for another to obtain the known benefit of being able to change application behavior without changing the fixed control program. (ii) US 3,516,062's express purpose is central control and identification of remote terminals — a POSITA seeking to service many remote terminals from one site would have been led to make the central site able to send more than enable signals, since the same channel and the same coded-message machinery are already there. (iii) The patent's own Background states the motivation in so many words: field data receivers create "data receiver down time caused by scheduled or unscheduled service time" that "disrupts the flow of business information... and decreases the cost effectiveness of the system." A POSITA reading that problem statement would look for remote service rather than a truck roll. That is the classic KSR "known problem, known solution" rationale.

Where Ground 1 fails. Nothing in these three patents teaches limitation (h) — the remote download of the customer application program over the telephone line into RAM — or (i), the relocation to a non-volatile area. Ground 1 persuades on the architecture and the data-handoff elements and on claims 2 and 4; it does not independently get to the full scope of claim 1 unless the examiner is willing to treat "program download over a phone line" as an obvious substitution for US 3,760,171's "program load from tape." That inference is available but is genuinely debatable, and it is the exact place a patent owner would fight.

Ground 2 — Claim 1: US 4,012,594 in view of US 3,760,171, US 4,193,112 and US 3,516,062

The value US 4,012,594 adds over Ground 1 is the explicit telephone-line write path into a terminal's memory: the terminal's main memory 30 holds many frames of buffered data, and the TRANSMIT function sends stored contents to "a central processor... via telephone line transmission." Substituting "data" with "program instructions" in an already-existing telephone-to-memory path is a simple substitution of one known element (data) for another (instruction words) to achieve a predictable result — the KSR "known technique, known improvement" rationale. US 3,516,062 supplies the two-directional, coded, centrally-controlled messaging that makes a service-computer→receiver command path natural.

Ground 3 — Claim 3 (printer host): add US 3,870,821

US 3,870,821 is titled a pushbutton-telephone printer/recorder. I could not verify its disclosure, so I use it only for what its face shows: telephone-line signals coupled to a printer. US 4,193,112 already discloses a printer 27 port in a microprocessor data communications system, which alone renders claim 3's "printer" alternative obvious as a mere choice of output peripheral. Claim 3 is the weakest dependent claim and should be rejected on US 4,193,112 alone.

Ground 4 — Claim 4 (reformatting): US 4,193,112

This is the cleanest rejection in the set. US 4,193,112's majik box 15 is a hardwired editing processor whose enumerated operations include Pad, Tab Set/Tab Clear, Single-Line Reset, Multi-Line Reset, Move, and Clear Mode A/B — i.e., field justification, padding and record layout — performed on data read out of RAM on CPU command and returned to RAM. Claim 4's "means for reformatting... into a predetermined record output format" (spec: right/left justify, date, time, yes/no, dollar amounts) is squarely within that teaching, aside from the specific field types, which are a trivially obvious selection. Claim 4 is obvious over US 4,193,112 alone, and a fortiori in view of Ground 1.

Ground 5 — Claims 5 and 6 (performance log and remote retrieval): not established on this record

Claim 5 requires counting predetermined receiver operations and storing the counts; claim 6 requires transmitting those counts to the remote service computer on command. I found no cited reference that counts operations for later diagnostic retrieval. US 3,516,062 shows a central data center and coded signalling to terminals, and US 4,193,112 shows CPU/RAM bookkeeping, but "gather operational statistics and let the service computer pull them over the phone" is not taught by any of the eleven. I will not stretch those references to cover it. Any rejection of claims 5–6 would have to rest on the DP 2001 NPL or on an examiner's "design choice / obvious to monitor a system's own operation" rationale — the latter is defensible under KSR but is exactly the sort of conclusory assertion that gets reversed on appeal.

Ground 6 — Claim 7 (error-triggered call-back): not established on this record

Claim 7 requires generating an error signal on a predetermined error in the customer application program, connecting the receiver to the remote service computer in response, and transmitting the error signal. That is an automatic dial-out, error-initiated diagnostic callback. None of the eleven cited patents discloses auto-dialing on a detected fault. The hearing-impaired-telephony references (US 3,746,793, US 3,896,267, US 4,012,599) are facially about terminal access to the telephone network, not about a machine dialing a service center on an internal error. I could not verify their contents, but their titles give no support; I decline to speculate. Claim 7 is the most defensible claim in the patent against this record.

The elephant in the room: the DP 2001 NPL

Two NPL citations are listed: Pinetree System, Inc., Model DP 2001 Data Prompter, pp. 1–4 (appearing twice). This is the applicant's own product literature and it was in front of the examiner. Its content is unknown to me, and I will not invent it — but analytically it is the single most important document in the prior-art set:

• If the DP 2001 brochure describes the Data Prompter as remotely programmable over ordinary telephone lines, it is the bridge over limitations (h) and (i) and would support a rejection of the whole of claim 1, and possibly a § 102(b) anticipation, since it is applicant's own printed publication.
• It may also implicate the on-sale bar/public-use bar if the DP 2001 embodied the claimed subject matter more than one year before 1982-02-18, on the theory that the commercial device practiced the later-claimed invention.
• Recommendation: obtain pp. 1–4 of that brochure before relying on this analysis. It changes the answer more than any other single document.

Relatedly, the copending Ser. No. 202,020 (filed 1980-10-28) is the applicant's own earlier application on the hand-held terminal. It is not § 103 art against the same inventive entity, and § 103(c) common-ownership practice did not exist as such at issuance. Do not let it be used as a combination reference.

Secondary considerations and counterarguments to expect

• No secondary-consideration evidence in the record. Nothing cited shows long-felt need, unexpected results, teaching away, or nexus-bearing commercial success. The Pinetree→Itron→Itronix acquisition history (from the earlier section) is a corporate transaction, not evidence of nexus.
• Teaching away: none apparent. US 3,760,171's rewrite-by-tape does not disparage phone-line loading; it is silent on it, which is neutral, not a teaching away.
• Non-analogous art objection: a patent owner would argue US 3,760,171 (a desk-top calculator) is remote from telephone data receivers. This is weak — a programmable data-processing device with a fixed program store plus a rewritable program store is reasonably pertinent to the problem of storing and revising program instructions, which is precisely what claim 1 claims.
• Means-plus-function scope: every limitation is "means for…," so under § 112 ¶ 6 (as then applied) the claim is limited to the disclosed structures (Z-80, 4K×8 EPROM 64, RAM 66, scratch pads 68/70, decode/select chips 72/74, control logic 76, tristate buffers 80, FSK 82, opto-isolator 84, latch 88) and equivalents. That narrows the claim and correspondingly narrows what the prior art must disclose, narrowing the gap on limitations (h)/(i). Under a narrow construction, a prior-art system in which a service computer writes program bytes over the phone into a battery-backed RAM would fall within (h) even without a separate "non-volatile" store, because the disclosed structure for the customer program is battery-backed RAM.
• Internal inconsistency to exploit or defend against: as flagged previously, the specification calls RAM 66 the volatile reprogrammable customer-program area while claim 1 recites moving instructions "from said random access memory to said non-volatile memory area," and claim 5 puts the performance log in a "non-volatile memory area" while the spec puts it in "a dedicated area of the customer application program RAM 66." A challenger can argue these are drafting artifacts that should be construed consistently with the spec, which reduces the difficulty of Ground 1 on limitation (i). A patent owner can argue the claims mean what they say. This is unresolved on the text; the 1985 certificate of correction may bear on it and I do not have its content.

Bottom line

The single highest-value next step is to obtain the Pinetree DP 2001 Data Prompter brochure, pp. 1–4, and the 1985-04-23 certificate of correction. Together they would determine whether claim 1 falls and how the "non-volatile memory area" limitations should be read. I have flagged rather than filled every gap where the record is silent.