Lee Hart's 1802 "Membership Card"


Last updated Nov 14 2014. Edited by Herb Johnson, (c) Herb Johnson, except for content written by Lee Hart and others.

[assembled kit]

This home page is about Lee Hart's Membership Card kits, based on the RCA COSMAC 1802 processor and the early ELF microcomputer design with that CPU. Current status, prices, contact and ordering information are at this link. The current kit support page is at this link which includes links to the construction manual and schematic.

This page also has links to notes on hardware, links to software including an assembler and FORTH; about 1802 history and resources, and other support. A summary history of the Membership card development and revisions is below, including links to discussion and design. Also, other people's builds and software for the Membership Card; and links to other 1802 resources. Finally, this page has recent 1802 news.

How do I load and run a program? Here's a Web page on how to manually operate the Membership card. There's example programs, too.

For comments and corrections of content on this and other Membership Card pages, contact Herb at www.retrotechnology.com, an email address is on that page..

Membership Card current and past revisions

[front cover]

[empty boards]

Rev G is in production since mid-March 2014. A serial interface and dual RAM/ROM were added as options. Here's the Rev G support Web page. Information and support for previous versions is listed below. To see Membership Card builds and software produced over all revisions, see the "other people's builds" section.

Current status, ordering, contact, support for Membership Card kits

Status Nov 2014: Rev G boards and parts in production since mid-March 2014. Available as boards and kits to present date. Contact Lee Hart as below.

Available: Bare Logic Boards (Membership Card and Front Panel), with schematic and construction manual;
OR Kit of Bare Logic Boards as above plus all components;
OR Kit as above plus Front Panel Cover board.

Purchase direct from Lee Hart on his Membership Card ordering Web page at this link.
Descriptions, prices and terms are on that page, including PayPal.
Contact Lee Hart for other terms or quantity orders.

Contact the developer: Lee Hart can also be contacted by email at [email addr] This is an image, not an email link.
Contact this Web site at: contact Herb Johnson at www.retrotechnology.com, an email address is available on that page.

News: Vintage Computer Festival Midwest in Sept 2014 included Lee Hart at an exhibit of COSMAC technology including the 1802 Membership Card. Chuck Yakym, Dave Ruske, Josh Bensadon exhibited as well.

Support: Check the Rev G support page for details of those boards and kits. Links to support Web pages for earlier revisions are listed on this Web page. See references at the top of this page for links to hardware, software, 1802 resources, and descriptions of what people have done with the Membership Card.

First question: How do I load and run a program? Here's a Web page on how to operate the Membership card. There's example programs, too.

Who are these guys?

Lee Hart designs, works on and discusses electric cars and designs EV electronics as products and for construction by individuals. Check my Lee Hart Web page which links to his electric vehicle site. Check the ordering section to contact Lee about the Membership Card.

I'm Herb Johnson, the producer of these pages and owner of this Web domain. Contact me at my home page for "retrotechnology". Wander from there to my other vintage computing and "retrotechnology" interests. This 1802 project is an example of, and a tribute to, the 1970's microcomputing era I'm trying to preserve and support. - Herb Johnson



Hardware and interface notes

Here's a link to note on how to operate the Membership card from the front panel, and test programs.

See the Membership Card hardware Web page, for a list and links to documents about hardware use of the 1802 Membership card. Among those notes are use of a PC parallel port and the M/S card's DB-25; adding ROM and RAM together and a serial port; serial loaders or USB loaders; low power operation; single-step operation; various ways to upgrade the M/S card; stacking M/S card CPU boards to double RAM, ROM and I/O; and some undocumented 1802 states between LOAD and CLEAR.

Serial interfaces for the Membership Card

The Rev G version M/S card, has a simple circuit on the Front Panel board, to provide RS-232 "serial" input and output. That circuit expects to use the Q and EF bits from the 1802, and a "bit-bang" or software UART, to manage ASCII or binary serial data. The vintage ROM monitor "IDIOT", provides such a software UART and a monitor program. Also: rev G can accept a narrow-width RAM chip, to mount under the wide ROM chip so a ROM monitor or other programs can operate with RAM.

For Rev F and earlier M/S card versions, with effort one can stack up RAM and ROM, and add an external serial interface. The alternative is to "upgrade" by buying the Rev G PC boards and adding components from your earlier boards; or to buy a Rev G kit. For Rev E and earlier, you also need to add a "ceramic resonator" for a stable clock circuit (like later revisions).

If you wish to perform "mods" like this on earlier Membership Cards, here's a 2014 tech note on a "ROM-stack for the 1802 Membership Card". A companion document describes serial interfaces and monitor ROM products. These are also informative about use of Rev G's RAM/ROM/serial. For Rev E and earlier M/S cards, here's notes on adding a ceramic resonator clock circuit, and stacking ROM and RAM. Look at the just-mentioned Rev F notes for a serial interface to Rev E and earlier.

Why are these revisions different? Well, you have to know the heritage of the 1802 Membership Card, and of the original COSMAC Elf.

The 1802 Membership Card kit is five years old as of Oct 2014; it's based on the COSMAC Elf from 1976. The 1802 Membership Card is a direct descendant of the COSMAC ELF, which preceeded almost all personal computers. The Membership Card, like most ELF-like COSMAC computers, operates with the 1802 microprocessor directly. It has a simple byte-binary interface of lights and switches, to load and run programs directly to and from memory. Lee Hart's Membership Card of 2009, wired-in a "PC parallel port interface" to operate the M/S card with software on a PC-compatible with a parallel port.

That said, today's computers connect to devices through USB, or USB-to-serial for legacy devices. Since 2014, in order to support "modern" computer interfaces to the Membership Card, Rev G also provides a hardware serial interface, plus support for both RAM and ROM to operate a ROM monitor, which can "drive" the serial interface. There's a classic ROM monitor available, called IDIOT, with that serial support.

Another choice, is to attach an external controller or microcomputer to the parallel port connector, to load software into the Membership Card RAM. Various M/S Card owners have made PIC, 8051, Arduino controller. Also a simple ROM and address counter circuit can be driven by a short COSMAC loader program. A number of Membership Card owners have implemented such methods. For example projects (not products), here's a serial loader or USB loader for Membership card. Here's a card to plug into the DB-25 with a ROM, counter and serial port.

See the Membership Card development page for years of discussion about the first Membership Card designs, and the philosophy behind them. Some design decisions are discussed there.

Lee Hart has produced a graphic of how the "elves" run the 1802. Lee also constructed some Membership Card operating notes and an 1802 instruction set summary. These can be printed and stored in the Altoid case. Here's the operating guide PDF version.

Lots of 1802 hardware, from the original ELF to the Membership Card, are discussed or documented on the Yahoo! Groups cosmacelf 1802 and ELF discussion group Web site. The corresponding Web site is cosmacelf.com.

Software notes and links

"How do I load and run a program?"Here's a Web page on how to operate the Membership card. There's examples, too.

This links to my Web page of the software I have available specifically for the 1802 and Membership Card. On this Web site, there's a Forth called 8th, a Tiny BASIC, a cross-assembler with C sourse, and PC parallel port software to drive the Card. Links to other sites are below.

"Here's a free-running, slow counter in 10 bytes: EF 80 BF AF 9E 5F 1E 64 30 01 . Can it be done in 9?" - Dave Ruske

Lots of 1802 software - assemblers, compilers, interpreters, monitors, 1802 assembly code - is discussed or distributed on the Yahoo! Groups cosmacelf 1802 and ELF discussion group Web site. The corresponding Web site is cosmacelf.com.

Hardware AND software

In 2012 there was a lively discussion in cosmacelf, about recovering data from audio cassettes used for data storage on VIP's and SuperELF's. Here's my gloss of VIP cassette data storage and here's my gloss on SuperELF and other cassette data storage There's links to recent work and software tools. I describe hardware too. So you could implement these on the Membership card! to see how cassettes were used on other vintage computers, check this Web page of mine. Lee Hart's 1802 single board BASYS also had a cassette interface.

Development of the COSMAC 1802, ELF, and the "Membership Card"

[1802 prototype] A breadboard of the Membership Card circuits. Ode to Eight Bits, by Lee Hart

RCA (later called Sarnoff Labs) developed the CMOS product line in the early 1970's, including the COSMAC 1802 CMOS microprocessor and other support chips. Some of RCA's history including COSMAC development, has been preserved in various venues as "Sarnoff Collections". RCA's design engineer also developed the "ELF" in 1975, a very simple kit to program the 1802 with nothing more than toggle switches. Over the years, variations of Elf-like 1802 products and kits were produced.

In 1982, engineer Lee Hart designed and built an 1802 single board computer called BASYS. He also developed a Forth called "8th", a Tiny BASIC, a ROM-only monitor, and other software tools.

Many ELF derivatives were produced in the decades since the 1975 ELF. ELF and and related 1802 products have been discussed for some time in the Yahoo! cosmacelf discussion group, the Cosmac Elf Web site by Dave Ruske, and other Web sites. A Web search will find them.

Lee Hart's Membership Card itself is a product of years of discussion among "cosmacelf" enthusiasts. What follows is a summary account of Lee Hart's 1802 work leading to the 1802 Membership Card. See the Membership Card development page for years of discussion about the Membership Card design, and the philosophy behind it. But a product did not emerge from those early discussions, before 2009.

In May 2008, I found out that Lee Hart wanted to resurrect his old 1802 FORTH; I and others helped to gather old code and documents to do that. That's when I found his earlier discussions in cosmacelf about his "membership card". By 2009, Lee was encouraged to pick it up again. He built a prototype and in October 2009 produced a few boards. I found a cross assembler in source form and made that available. I established these Web pages on my site to support the work, and to capture and make available his design discussions.

By February 2010, he produced several "Rev A" cards. After a chip change, in August 2010 he produced a "Rev B" production run, and kits continue to be produced and sold. Various versions have been sold continuously to this date. The most recent status of the project, and contact and price information, are given above. Here a link to current and previous version support pages.

Current and out of production versions

the current "Rev G" as of mid_Feb 2014 is described on the Rev G support Web page.

"Rev F" was announced in May 2013 and is out of production as of Feb 2014.Here's the Rev F support Web page.

"Rev E" was announced in Jan 2013 and is out of production as of May 2013. Minor changes in PC board layout. Here's the Rev D & E support Web page.

"Rev D" was announced in July 2012 and is out of production as of Fan 2013. Here's the Rev D & E support Web page. Changes from Rev C to D include customer options to change the I/O port address, to stack two CPU cards to double ROM/RAM and double I/O ports, and to provide 8 bits of output on the DB-25 connector.

A "Rev C" card set was announced in July 2010 and sold through June 2012. There's very minor changes from the Rev B, plus an additional PC board as a printed front panel cover. Here's the Rev C support Web page. with construction manual and schematic. Supporting information about the Rev B also applies to the Rev C.

A "Rev B" card set was announced in mid-August 2010, and sold through July 2011. Here's the Rev B support Web page.

Chuck Bigham and Chuck Yakym completed Rev B kits in Jan 2011, and developed some PC/windows software. See the "others" section below for PC connecting software for the Membership card.

Several "Rev A" prototypes were produced in late 2009 and assembled and tested in 2010. Rev A Web pages are still available and useful. Here's a photo of the assembled Rev A 1802 Membership Card. Later versions look and operate almost the same.

Here's a more detailed history of 1802 Membership Card production.

Other people's builds, software, hardware for the Membership Card

The Rev A prototypes were constructed by a few people: here's my [Herb Johnson] build from 2010.

P. Todd Decker completed and debugged the rev A kit in May 2010, and provided Lee Hart and myself with discussion about some design issues, resolved in the Rev B version. hear's Todd's assembly and debugging of a Rev A kit, including notes for a "single-step" device. Todd produced a demonstration video on YouTube in July 2010, titled "COSMAC 1802 Membership Card Checkout" by ptdecker. Photos appear on FLickr titled "1802 Membership Card" by ptdecker. Todd has a Facebook page as ptdecker.

Chuck Bigham completed a Rev B kit in Jan 2011. Chuck has connected his Membership Card to a Windows PC via a Pixaxe conroller. Check the software Web page for details and links.

Chuck Yakym built a Rev B kit in early 2011, and created a Windows 32-bit program (Win XP, 7) to access and program the Membership card through the PC parallel port. Check the software Web page for details and links. Also check the cosmacelf Yahoo site for other 1802 programs by Chuck.

Mark Moulding AKA "urrossum" built a serial loader for the M/S card in March 2012. It uses a ATMEL AT89C2051 as a serial to parallel converter. Here's a tech note about his work.



other 1802 resources

The cosmacelf Yahoo discussion group and the Cosmac Elf Web site by Dave Ruske are notible resources for ELF, ELF derivatives and the 1802.

a COSMAC VIP and CHIP-8 Yahoo group.

Documents and articles

Lee Hart suggests A Short Course In Programming by Tom Pittman, provided with permission.

Lee also says "The RCA Microtutor Manual is a good place to start. It was written by Joe Weisbecker himself (inventor of the 1802), and starts right at ground zero, for someone with zero prior microcomputer experience." This is not available online, apparently. Copies and originals are not uncommon.

He also suggests a look at the orignal ELF articles from Popular Electronics. are on Rich Cini's section of the classiccmp.org Web site. The Web page is an index of many documents, look for the Cosmac ELF PDF's. Other sites will likely have copies of these articles.

Steve Gemeny, an active member of Yahoo's cosmacelf group, worked on a number of NASA spacecraft projects at the Johns Hopkins Applied Physics Laboratory (JHU/APL). In 2002 and 2005, Steve posted in cosmacelf, remarks about his experiences with the 1802 as a teen in the 1970's, and again as a parent showing his 1802 kit to his son. He also describes 1802 history from his experience in aerospace, and examines early use in medicine. Read his remarks, made available on this site in July 2011 with his permission. A further discussion of the 1802 in spacecraft is on another Web page.

Web links to other ELF 1802 sites:

Many of these references were discussed in the cosmacelf Yahoo group.
Mike Riley's Elf Web page with micro/Elf and pico/Elf designs and considerable software;
Elf 2000 from Spare Time Gizmos;
the tinyELF emulator for Mac OSX (PowerPC or Intel versions);
an ELF simulator in javascript from Poland;

Matthew Mikolay, AKA mattmik has posted on his Web site the book Programs for the COSMAC ELF by Paul C. Moews; and issues of "VIPER" newsletter. VIPER was produced by Terry Laudereau and later Ray Sills. The "Programs" book is online with permission of the author.

Ted Rossin's RCA 1802 Web site. He has a C compiler, 1802 simulator, some PIC support from the 1802, lots of ELF work old and new.

The chip8 Web site is dedicated to current versions of the CHIP-8 game program language developed by COSMAC developer Joseph Weisbecker. Apparently CHIP-8 was reimplemented numerous times in the decades since the COSMAC ELF, for graphical calculators; then as a general emulator in the 1990's. It seems to be one of the subcultures within vintage videogaming culture.

1802 news, history, events

Vintage Computer Festival Midwest in 2014 included Lee Hart at an exhibit of COSMAC technology Including the 1802 Membership Card. Chuck Yakym, Dave Ruske, Josh Bensadon exhibited as well.

Vintage Computer Festival East in 2014 included an exhibit by Herb Johnson of the Membership Card and other COSMAC technology with items from Bill Degnan, the Sarnoff Collection, Kyle Owen and Flash Corliss.

Prices for the 1802 Membership Card boards and kits are listed above via this link.

1802 history in space: Note: this section has been moved to its own HTML document. The most notible bits of history, is that contrary to prior information on the Web and elsewhere, The 1802 was not used in the Voyager or Viking planetary spacecraft. It was used in Galileo, and in other craft prior and after. Read the linked document for details and primary references to confirm. - Herb Johnson, Aug 2011

Lee Hart explains why he designed the Membership Card in these notes to HackADay, a popular site for individual projects.

Archives of RCA's 1802 development history were moved from Sarnoff Labs to two institutions in 2009-10. A display of artifacts is in progress as of 2012, at one venue. Read the linked Web page for details.

During May 5-6 2012, a Membership Card semi-kit was shown at my S-100 computer exhibit at the Vintage Computer Festival - East 8.0. near Wall, NJ USA. I previously showed the Membership card on May 14-15 2011 at the Vintage Computer Festival - East 7.0 at the same location. The flyer is based on the product sheet Web page. A number of people knew about the Membership Card, or had owned various ELF kits over the decades.



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

This page and edited content is copyright Herb Johnson (c) 2014. Contact Herb at www.retrotechnology.com, an email address is available on that page..