COSMAC 1801, 1802 "dates"

COSMAC 1801, 1802 "dates"

Last updated Dec 11 2018. Edited by Herb Johnson, (c) Herb Johnson, except for content written by others. Contact Herb at, an email address is on that page..


This Web page is about earliest dates of development, introduction and production of the RCA COSMAC 1802 and 1802 microprocessors. Various documents are cited to provide dates. Thanks to Dave Ruske of cosmacelf for his references and reviews of early publications. Also to the TCNJ Sarnoff Collection. This is one of many Web pages which support the COSMAC 1802 "Membership Card" created by Lee Hart.


pre-microprocessor design From 1971 forward, Joseph Weisbecker, a RCA programmer and engineer, and a number of RCA engineers and techs, built a series of TTL-based computers, of a design which later became the COSMAC microprocessor and video controller. By 1973, several "FRED" computers were in use by these engineers to develop code, coding languages, and games. The languages were essentially use of routines or macro-instruction libraries of I/O and other functions. The FRED computer supported simple block graphics, audio, and audio-cassette file storage - features of the VIP and later COSMAC computers and other video-based microcomputers to come. The FRED also supported a simple punched-card reader, cards were hand-punched. Much of the coding was in hex object code, hand assembled on preprinted coding sheets.

In late 2013 I became aware of internal RCA Laboratory Research Reports, available on-line, which describe COSMAC development. My review of these is early and tentative, but they "date" a number of COSMAC developments for FRED, COSMAC as microprocessors, and the MicroTutor and MicroKit development tools. Here's my Web page where I review the 1973, 1974 and 1975 reports. In 2016, copies of Weisbecker and other's documents on those TTL-based prototypes, appeared from the Hagley Library. Here's a rough timeline of what I believe those reports & documents describe:

1971 - construction of "System 00" by Joseph Weisbecker as TTL implementation.
1972 - "prototypes" of 2-chip COSMAC processor
1973 - 2-chip implementation in COS/MOS at Palm Beach Division
1973 - "FRED" TTL-based computers enhanced, more programs
1973 - PBD provided "prototyping hardware to the Systems group and to other customers...breadboard"
1974 - production of chips by SSTC, "hardware prototyping kits by the Palm Beach Division", probably MicroKits?
1974 - MicroTutor design, documents
1975 - MicroKits delivered in mid-January 1975
1975 - MicroTutor prototypes, with 2-chip COSMAC
1975 - COSMAC processor production by Solid State Division. Single chip COSMAC
1976 - 100 MicroTutors produced by release of 1975 Research Report (probably mid-1976?)
late 70's - several models of COSMAC development systems

COSMAC processor: Before the processor was designated "1801", papers about the COSMAC microprocessor were published in 1974 and 1975, including in IEEE Computer magazine, and in conference proceedings. Many were authored by Joseph Weisbecker. The earliest COSMAC microprocessor design publication, is a March 1974 IEEE Intercon paper. An RCA Engineer magazine article is dated Feb/Mar 1974. On October 15, 1974, patent number 3,970,998 was filed for the COSMAC architecture. A copy of the RCA data sheet "Digital Integrated Circuits - Developmental Types - TA6889, TA6890" is dated "2-75" (Feb 1975)"

COSMAC 1801: RCA document MPM-101 was printed in May 1975, and describes the COSMAC architecture, but only names it "1801" in an update notice. RCA document ICAN-6416 is an application note on COSMAC microprocessors, which was printed in Oct 1975.

COSMAC 1802: A preliminary RCA datasheet on the 1802 was printed in Feb 1976.

Weisbecker authored the COSMAC ELF kit article in Popular Electronics beginning in August 1976. The ELF and its successors were simple and popular 1802 microprocesor kits which could be operated and programmed without any other devices needed. Variations of this kit have been available ever since, including into the 21st century.


I have a Web page about the earliest TTL prototypes, "System 00" and "FRED" which include links to original documents about those computers by name.

Exerpts of RCA Laboratory Research Reports of 1973, 1974, 1975

This is the cover of the RCA document MPM-101 titled "microprocessor Products" by RCA. It describes the COSMAC 1801 architecture, apparently before it was named "1801". This was a two-chip implementation. Later in this document I provide a Web site reference to obtain a copy.

This is the title page of the RCA document MPM-101. Note "copyright 1975" and "printed in USA 5/75". That suggests a publication date of May 1975.

This is a note inside the cover page, of the RCA document MPM-101. It's the only reference in the document to "COSMAC CPD1801" and it suggests this document was written BEFORE the 1801 was released as a physical product. It says the 1801 has or lacks features which were documented in this publication.

This is the cover of the RCA document "preliminary datasheet, Microprocessor Products CDP1802D CDP1802CD" with a descriptor "printed in USA 2/76". that suggests a publication date of Feb 1976.

This is the cover of the RCA document "Digital Integrated Circuits, Application Note ICAN-6416, An introduction to Microprocessors and the RCA COSMAC COS/MOS Microprocessor". with a descriptor "printed in USA 10/75". that suggests a publication date of Oct 1975. Copies of this note may be in some RCA COSMAC microprocessor data books. Note: if this document is not available online currently, let me know and I'll provide a PDF of it, either here or to Dave Ruske's cosmacelf site.

This is the back of the RCA document ICAN-6416. There are several references to documents by title, author, publisher and date. among them are a March 1974 IEEE Intercon conference paper by Weisbecker on COSMAC microprocessors; IEEE Computer magazine articles for March 1974 and August 1974; and 1975 references to "microprocessors" in three other publications.

The Sarnoff Collection at The College of New Jersey has a collection of documents and artifacts from Joseph Weisbecker's work. These include early games, COSMAC computers, and an earlier TTL implementation of the COSMAC microprocessor called "FRED". As of late 2013 the cataloging and curation of these are in progress, but some items are on public display as part of Sarnoff history. In 2013 I assisted the Collection in preserving, documenting and archiving these items, among other related electronic technology.

I assisted the Sarnoff Collection again in 2017-18; a major achivement was to digitize their collection of over 100 audio-cassette program tapes from Joseph Weisbecker's mid-1970' COSMAC archives. By late 2018, those were converted back to binaries and run under emulation. The tapes held by the Hagley Library were also digitized by the Hagley, and then converted and emulated. Read the amazing details of that effort on this linked Web page.

Notes, references from Dave Ruske

Press releases and conference papers date sample/development availability of the CMOS two-chip microprocessor to early 1974. They suggest work on the architecture and applications was done over a period of years. Dave operates the Web site and administrates cosmacelf Yahoo group. Here's his references for 1801 and 1802 development and production from discussion with me in April 2013. The link given here is to his "history" Web page. - Herb Johnson

According to the Sarnoff Museum curator, 1970-71 was the time frame for work on the original invention of the COSMAC processor; no reference was cited. Published references in 1974 are the earliest things I can put a solid reference to.

March 25 and 26, 1974 - 1974 IEEE Intercon technical program session by Norman P. Swales and Joseph A. Weisbecker of RCA, session 17/2. There's no 1801 designation in the paper; the architecture is referred to only as COSMAC, here. Numerous missing opcodes in the paper (most of the 7x opcodes) and a statement that "COSMAC is presently implemented on two chips" suggest that the paper refers to the 1801. A couple paragraphs later, the paper says "It is anticipated that the processor will soon be implemented on a single chip."

March 1974 article "A Simplified Microcomputer Architecture." by Joe Weisbecker in IEEE Computer magazine pages 41-47. The article reprint number is 0703041. The instruction set isn't described in as much detail in this article, and again the microprocessor is only referred to as COSMAC. The article suggests the 1802 may have been in the works: "Since a single-chip microcomputer promises minimum cost, the architecture was constrained to a 40-pin interface."

August 1974, Weisbecker again published in IEEE Computer with "A Practical, Low-Cost, Home/School Microprocessor System" on pages 20-31. He describes a COSMAC-based computer named FRED (Flexible Recreational and Educational Device), a precursor of the VIP. "The basic FRED system comprises the RCA COSMAC microprocessor, 1024 bytes of RAM, a simple hex keyboard, an inexpensive audio cassette player, and the user's own TV set." The article gives a high-level overview of Pixie graphics (though not named as such) and cites the preceding two publications as references. About half the article is pure evangelism, explaining the tasks such a machine could be put to and how it could be commercialized.

On October 15, 1974, patent number 3,970,998 "Microprocessor architecture" was filed for the COSMAC architecture. It was published Jul 20, 1976.

- from discussions with Dave Ruske, with permission

note - patent 3970998 refers to another patent 3,798,615: "Computer system with program-controlled program counters" Application Date 1972-10-02; Publication Date 1974-03-19; Inventor Weisbecker, Joseph A; assigned to RCA. In turn it's cited by 9 other patents. This patent talks about implementing a "Micro" computer architecture on one or two additional chips. Thanks to Dr. Vincent Crabtree for this reference.

Other sites

A number of private Web pages and various group pages, cover the COSMAC 1802. There's modest 21st century interest, as more RCA material and hardware and software is found. Web search will find many such resources. (and its mirrors, look them up) have a number of RCA COSMAC documents as document PDF's as of 2013. "Users_Manual_For_The_COSMAC_Microprocessor_May75.pdf" is one of them, under their PDF's of manuals and under RCA and COSMAC. Their copy of that manual also includes a scan of the 1974 IEEE Intercon paper; a Computer Design magazine article from april 1974; and a Feb 1974 RCA press release on their CMOS two-chip microprocessor. Bitsavers also has the 1801 datasheet as document "TA6889_TA6890_Data_Sheet_Feb75.pdf". (Thanks to Will Donnelly for the datasheet reference.) has a series of RCA articles on its site. The earliest includes a Feb/Mar 1974 article in RCA Engineer magazine "Simplifying Microcomputer Architecture" by J. Weisbecker with the note "manuscript recieved November 26 1973".

Dave Ruske operates which provides early and current information about the COSMAC 1802. Dave moderates the cosmacelf Yahoo discussion email list.

Bill Degnan obtained an early RCA MicroKit with the two-chip processor during 2013. The two CPUs are labled "TC1084 - 7509" implied date March 1975, and "TC1085 7449" date of Dec 1974. He found this reference to the early MicroKit from RCA: an article on, about the Microkit that came out later in 1975. Published in Microcomputer Digest for Oct 1975. I have some software notes about that MicroKit on this linked Web page.

The Sarnoff Collection at The College of New Jersey has a collection of documents and artifacts from Joseph Weisbecker's COSMAC work. The link is to a database of cataloged items. Other pages and related sites show the exhibited collection.

Contact information:
Herb Johnson
New Jersey, USA
To email @ me, see
see my home Web page.

This page and edited content is copyright Herb Johnson (c) 2018. Copyright of other contents beyond brief quotes, is held by those authors. Contact Herb at, an email address is available on that page..