User Manual For The Cdp1802 Cosmac Microprocessor
RCA CDP1802とは、1976年はじめにRCAが初のシングルチップマイクロプロセッサとしてCOSMAC (Complementary Symmetry Monolithic Array Computer) アーキテクチャに基づき40ピンLSIパッケージの集積回路に実装した 8ビット CMOS マイクロプロセッサである 。. COSMAC VIP (Video Interface Processor) CDP18S711 is a complete computer on a single printed-circuit card. It includes the following:.RCA CDP1802 Microprocessor (91 instructions).2048-byte RAM.Built-in hex keyboard (modern reliable touchpad type).Graphic video display interface (standard video output).100-byte-per-second au dio cassette.
'The first project, COSMAC Elf - 30th Anniversary Edition, was developed Dec 2005 - Jan 2006. This is a microprocessor training system based on the CDP1802 microprocessor, and an Aug 1976 magazine article. The prototype was produced early Feb 2006, and the second later the same month.' In the process of rediscovering the vintage RCA COSMAC CDP1802 microprocessor (RCA 1802 Micro), I decided to create my own simulator (some prefer 'emulator').What better way to fully understand the machine code operation of a micro than to write simulation code for every instruction! The COSMAC 1802 was created in the 1970's at the dawn. Cover Card, CDP1802 microprocessor, 32K RAM, manual, and Altoids tin. Tiny BASIC User Manual by Tom. The RCA CDP1802 (aka RCA COSMAC) is an 8-bit low power microprocessor introduced by RCA around mid 1970's. It was used by many popular early computers (like all the COSMAC ELF variants & VIP in the USA and Telmac in Finland) and has also gone to space controlling satellites (military version is highly resistant to radiation and ESD).
Last updated Dec 7 2020. Edited by Herb Johnson, (c) Herb Johnson, with content written by Lee Hart and others.
What is this kit?
The description and support Web page for the current Rev K3 kit, with K front panel and K3 CPU board set, is at this Web link. Rev K3 has been in distribution since Sept 2020. The previous Rev JK2 kit of the Rev K2 CPU and J front panel set, was distributed from July 2019. And there's astarter special kit with CPU board, programmed 32K EPROM, and 32K RAM. The 1802 Membership Card has been in distribution since mid-2010, developed earlier.
The 1802 Membership Card full kit, provides a complete COSMAC 1802 computer you can build and program, without use of any other computer! Just like the original series of 'COSMAC Elf's. Or, assemble the CPU board only with a ROM monitor, and run it from a serial connection. With the CPU board's ROM monitor and a serial connection to a computer USB or serial port, you can operate the card. Adding the front-panel card to the CPU card, permits manual operation and provides hardware bits in and out. Adding a protoboard, let you build and add your own electronics.
This Web page provides summary information, with links to many other Web page resources on this site, to results from 1802 M/S card owners, and more. Every version of the 1802 MC is covered.
HOW TO ORDER: Purchase direct from Lee Hart on his Membership Card ordering Web page at this link. Products, descriptions, manuals, prices and Paypal terms are on that page. Lee Hart can also be contacted by email at This is an image, not an email link.
Available: Bare Logic Boards (Membership Card and Front Panel), with schematic and construction manual;
ORA 'starter special' CPU board, programmed 32K EPROM, and 32K RAM;
OR A Kit of Bare Logic Boards as above plus all components;
OR A Kit as above plus Front Panel Cover board;
AND a protoboard for custom interfaces. Here's details about the protoboard.
ALSO There's a Clock kit front-panel, described and for sale on Lee Hart's ordering Web page.
AGAIN: Purchase direct from Lee Hart on his Membership Card ordering Web page at this link.
The complete kit comes with parts and boards and build instructions in a classic manual! Boards are also available without parts. And, there's a CPU board only with ROM and RAM. Also a protoboard is available. The kit's sales Web page, links to documents and describes the current features of the 1802 Membership Card. There's links to downloadable ROM software; and descriptions of some 'builds' of the kit. Also: a clock board kit is available, which runs from ANY version of the 1802 Membership Card CPU board.
What's on THIS Web site for the 1802 Membership Card?
This Web page has links to notes on hardware, links to software including an assembler, BASIC, FORTH and ROM monitors; about 1802 history and resources. There's a summary history of the Membership card development and revisions, including links to previous versions' Web pages here. Also, links to other people's builds and software for the Membership Card; and links to other 1802 resources. Finally, this page has recent news about the 1802 Membership Card.
HOW TO ORDER, status, contact, support
Hardware and interface notes
Software notes and links
Modern microcontrollers, other people's builds, for the Membership Card
1802 M/S card news, events
Current and out of production versions
A summary history of the Membership card
Development of the COSMAC 1802, ELF, and the 'Membership Card'
other 1802 resources
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..
Production and Support:
Links to the current 1802 support page is at the top of this Web page. To order, see the link to Lee Hart's sales page. Information and support about previous versions is linked below. To see some Membership Card builds and software, see the 'other people's builds' section. More information is linked from this Web page. There's many other Web pages on this site for the 1802 MC and the COSMAC;try a Web search and add the phrase 'site:retrotechnology.com'.
ROM monitor, BASIC:Binaries of a ROM monitor and BASIC are available from the 1802 M/S Card sales Web site. Here's operation of the Rev J M/S card with BASIC 3 and an FTDI-chipped USB serial adapter.
Also: If you want an old-skool ROM monitor, RAM and a serial connector: Parts, serial connectors, IDIOT monitor ROM and RAM, is described on this linked Web page. There's other 1802 ROM monitors and programs on this Web site, and other Web sites. See the software notes below for details.
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.
Recent news:See the News section for more details on recent and earlier events. The 1802 M/S card has been sold at various vintage computing events. It's described on various Web pages, blogs and discussion groups. A gallery of 1802 Membership Cards is shown on the cosmacelf.com Web site.
Who are these people?
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.
Herb Johnson is the producer/editor of these support Web 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
What is this kit about?
See the top of this Web page. ;)
Other people's builds, software, hardware for the Membership Card
Hardware and interface notes
Here's a link to notes about testing and operating your 1802 M/S card. Itdiscusses how to operate the Membership card from the front panel, and provides test programs.
See the Membership Card hardware Web page, for a list and links to documents about the hardwareof 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, parallel or USB loaders; low power operation; single-step operation; various ways to upgrade the M/S card (discussed below); stacking M/S card CPU boards to double RAM, ROM and I/O; and some undocumented 1802 states between LOAD and CLEAR.
How to expand the 1802 M/S Card hardware & software
Some history: The 1802 Membership Card kit will be TEN years in production as of Oct 2020. But it's based on the Popular Electronics magazine 'COSMAC Elf' from 1976 which preceeded many personal computers - so the Elf had to be simple. Very few people in 1976 had computers, or keyboards, or anything 'digital' - so the ELF operated from lights and switches in binary. The 1802 Membership Card is a direct descendant of the COSMAC ELF. Both have a simple byte-wide set of lights and switches, to load and run programs directly to and from memory - like the ELF. Lee Hart's Membership Card also has a 'PC parallel port interface', to operate the M/S card with that old 'PC standard'. And, that M/S Card binary interface can operate external devices, or those devices can operate the M/S card. And there's a serial interface too, but it needs software to operate, and modern USB-to-serial hardware to connect to a computer's USB port as a serial device like a terminal. This section discusses all these 'modern' options for the vintage 1802 Membership Card.
RAM and ROM options: Recent versions accept a narrow-width RAM chip, to mount under the wide ROM chip so a ROM monitor or other programs can operate with RAM. Basic instructions to set these up, are in the kit assembly manual. A more general and technically detailed discussion of the serial interface and operation of a ROM monitor is on this linked Web page.
Serial options: Recent versions have circuits on the Front Panel board to provide TTL or RS-232 'serial' input and output interfaces. They use the Q and EF3 bits from the 1802, and a 'bit-bang' or software UART, to manage ASCII serial data. The 1802 monitor or BASIC programs, can provide a software UART and operating commands. Recent versions have a power/serial connector for convenient connection to a TTL-to-USB adapter; or one can add a RS-232 like serial interface. A kit of serial connectors, IDIOT monitor ROM, and narrow RAM, is described on this linked Web page. The sales Web page includes ROM codes for a monitor and BASIC.
Here's operation of the Rev J M/S card with BASIC 3 and an FTDI-chipped USB serial adapter.. There's also a link there, to discussion about use of USB-to-TTL dongles or devices. If you assemble the CPU board only, you can wire it to a TTL to USB device and operateit under a ROM monitor in a similar way.
To support and upgrade earlier Membership Card versions, look for the list of previous versions on this Web page. Read those support Web pages, for notes and links to other Web documents. There's notes on changes, and on ways to add RAM and ROM, and to build serial and USB interfaces. These 'old notes' are also informative about use of the current revision - that's the other reason we keep them around.
Parallel and binary interfaces: Beyond connecting to binary devices, another choice is to attach an external controller or microcomputer to the parallel DB-25 connector, to load software into the Membership Card RAM; or to control one microcomputer from the other. Various M/S Card owners have attached PIC, 8051, Arduino controllers. See this Note about use of the parallel port by old PC's, with links to examples of use of microcontrollers. The hardware interface can also be driven by 1802 programs, like any other microcontroller. Here's a project to plug into the DB-25 with a ROM, counter and serial port.
ROM monitors: The Membership Card Kit does NOT include a ROM chip with a software ROM monitor, but Lee Hart provides binaries, see his distribution and sales Web page. So you could burn a monitor into a UVROM; or ask someone to do that for you. On this Web site there links-to or Web pages of, a number of ROM monitors, FORTH, BASICs, available in 1802 source and/or binary; and 1802 assemblers. Details of some software are on our Software Web page.
Audio cassettes for data: In 2012 in the cosmacelf Yahoo (now groups.io) discussion group, 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 work done in 2018 to recover RCA's COSMAC cassette tapes, including new 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.
More history of development and applications
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 groups.io cosmacelf ELF 1802 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.
Lee Hart provides a BASIC, a Tiny BASIC, and a ROM monitor; as binary images forROMS or binary download into RAM. See his 1802 M/S card sales page and look for software. Details are in the ZIP files and on his site. Here's operation of the Rev J M/S card with BASIC 3 and an FTDI-chipped USB serial adapter.
This links to my Web page of the software I and others have available for the 1802 and the 1802 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. On other Web sites, there are a C compiler, 1802 emulators for specific COSMAC computers, Membership Cards operated with Raspberry Pi or Arduino, and more. Some other 1802 related Web sites are listed elsewhere on this Web page.
'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 groups.io cosmacelf ELF 1802 discussion group Web site. The corresponding Web site is cosmacelf.com.
1802 news, history, events
Sept 2019: Lee Hart and others displayed the 1802 M/S card and other COSMACs, at the VCF-Midwest 14 near Chicago.
Dec 2018: An article on the 1802 MC was published on EEWeb, by Max Maxfield. Microcomputer Retro-Kits That Fit in Altoids Candy Cans covers the 1802 MC, and points to Lee Hart's other Altoids-class microcomputers.
Sept 2018: Lee Hart and others displayed the 1802 M/S card and other COSMACs, at the VCF-Midwest 13 near Chicago.
May 2018: Herb Johnson demoed and sold the 1802 M/S card, at the VCF-East 2018 event in Wall NJ. Look for 'Vendors', 'RetroTechnology.com' for references and photos; the Web page references all the vendors, exhibits, and talks. Here's a photo of the 1802 M/S Card in the wild, running BASIC3.
Sept 2017: Lee Hart and others displayed the 1802 M/S card and other COSMACs, at the VCF-Midwest 12 near Chicago. Look for 'VCFMW/ECCC12 (2017)' on that Web page, for a list of Web pages of photos.
Apr 2017:HErb Johnson displayed and sold the 1802 Membership Card at VCF-East 2017 in Wall NJ. There were many vintage computing exhibits, and several vendors. Here's my table.
Sept 2016: The 1802 M/S Card was sold by Lee Hart at the VCF-Midwest Festival 2016, near Chicago. Lee and several M/S card owner-developers gathered to mark the 40th anniversary of the COSMAC ELF. They provided a hand-wired ELF kit as a prize; and an ELF design modified for modern parts. Photo from Dave Ruske used with permission. Read this report from Lee Hart about the event, describing the 1802 exhibits.
April 2016: The 1802 Membership Card was sold at Vintage Computer Festival - East XI in Wall, NJ.
Aug 2015: Lee Hart and the 1802 Membership Card appeared at Vintage Computer Festival - Midwest near Chicago. 'A guy at the show was intrigued by the 1802, learned its instruction set from the little fold-out card, and wrote a little program to 'krell' the Q LED. This means sending pulses of different widths to the LED, so it gradually gets brighter, then fades back out, and repeats. The name comes from the old 'Forbidden Planet' movie, where all the lights on the control panels did this.
June 2015:A gallery of 1802 Membership Cards is shown on Dave Ruske's cosmacelf.com Web site. That's a premier Web site for ELF and 1802 information. Dave Ruske also moderates the groups.io cosmacelf discussion group.
April 2015: The 1802 Membership Card was sold at Vintage Computer Festival - East 10.0 in Wall, NJ. The image shows an old laptop as terminal, operating the M/S card IDIOT monitor via serial port. The 'kit' Herb Johnson sold at VCF-E, with serial connector, IDIOT monitor ROM and RAM, is described on this linked Web page.
The March 2015 issue of IEEE Spectrum magazine, an academic-oriented publication for electrical engineers, is an article by Stephen Cass on the 1802 Membership Card. '...Here Comes the COSMAC Elf' features some mention of ELF history, features of the 1802 and the Membership Card, and links to this site, cosmacelf.com and Lee Hart's sales site. A good number of kits were sold following publication. In a follow-up blog entry Stephen describes how he used an Arduino Mega to 'drive' the M/S card and load and run programs, and to drive a MAX6971 to operate a 2-hex-digit display.
Vintage Computer Festival Midwest in 2014 included Lee Hart at an exhibit of COSMAC technology Includingthe 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 COSMAC items from Bill Degnan, the Sarnoff Collection, Kyle Owen and Flash Corliss.
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.
Lee Hart explains why he designed the Membership Card in these notes to HackADay, a popular site for individual projects.
Archives of RCA documents and artifacts including 1802 COSMAC and CMOS development history, were moved from Sarnoff Labs to various institutions in 2009-10. A museum display of artifacts is at one venue. I've collected some stories about techs and engineers who used, or who now own, early COSMAC development products.Read the linked Web pages for details.
Current and out of production versions
Prices and ordering info for the 1802 Membership Card boards and kits are via this link.
The Rev K3 CPU and K front panel are in current distribution as of Sept 2020. The K front panel is a printing change (silk screen) only from Rev J. The K3 CPU has a single chip change from K2. See the linked Web page for details.
Nov 2019: A 'starter special' kit with the current CPU board, a programmed 32K EPROM, and a 32K RAM chip. See the linked page for details.
'Rev K2' CPU and Rev J front-panel were in distribution as of July 2019. The K CPU's 74HC244 input buffer was replaced on the K2 with a 74HC541, to eliminate extra power consumption during the time between CLEAR and the first LOAD cycle. See the JK2 Web page for details.
'Rev J2' was in distribution as of Jan 20 2019. That's the Rev J2 CPU board with Rev J front panel is in current distribution. The CPU's 4093 is replaced with a 74HC132. See the Rev J2 Web page for details.
'Rev JK' was in distribution as of Aug 1 2018. That's the Rev K CPU board, and the Rev J front-panel. The Rev K CPU changed the operation of the CPU clock. Here's the Rev JK support Web page link.
'Rev J' CPU and Front-panel were in distribution as of July 1 2017. The front panel had some changes from Rev I. No change on the Rev J CPU board; its distribution ended Aug 1 2018. Here's the Rev J support Web page link. Rev J CPU was retired in Jan 2019.
'Rev I' was in distribution as of Feb 1 2017 as a front panel, and since April 2017 as a CPU board. Here's the Rev I support Web page.
Alarm clock: sometime ago, Lee Hart started production of an alarmclock front panel to operate the 1802 MC as an alarm clock. Check this Web page and his Web pagefor details.
'Rev H2' was in distribution as of June 4 2015 as a CPU board, with Rev H front panel, until Jan 31 2017. Here's the Rev H and H2 support Web page.
'Rev H' was in distribution as of Apr 21 2015, and as supplies lasted after Rev H2 which was a minor change. See the Rev H support Web page.
User Manual For The Cdp1802 Cosmac Microprocessor Instruction
'Rev G' was announced in mid-Feb 2014 and is out of production as of mid-April 2015. Here's the Rev G support Web page. Some Rev H CPU boards were distributed with Rev G front-panel boards; that too is supported on the Rev G support 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.
User Manual For The Cdp1802 Cosmac Microprocessor Software
'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.
User Manual For The Cdp1802 Cosmac Microprocessor System
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.
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.
A breadboard of the Membership Card circuits. Ode to Eight Bits, by Lee Hart
RCA research (later called Sarnoff Labs) developed the CMOS product line in the early 1970's, including the COSMAC 1802 CMOS microprocessor and other support chips, including software and development hardware. I've collected somestories about techs and engineers who used, or who now own, those early products.Some of RCA's history including COSMAC development, has been preserved in various venues as 'Sarnoff Collections'. RCA's lead COSMAC design engineer Joseph Weisbecker, also developed the 'ELF' ,and wrote a construction article for itin Popular Electronics published in August 1976. It's a very simple kit to hand-wire, and to program the 1802 with nothing more than toggle switches. Over the decades, variations of Elf-like 1802 products and kits were produced in an almost continuous run.
In 1978-9, 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 groups.io cosmacelf ELF 1802 discussion group Web site, 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.
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. See the Membership Card development page for years of discussion about the Membership Card design, and the philosophy behind it.
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, six years plus as of 2017. The most recent status of the project, and contact and price information, are given above. Here's a link to Current and previous version support pages.
other 1802 resources
The cosmacelf groups.io email discussion group and the Cosmac Elf Web site by Dave Ruske are notible resources for ELF, ELF derivatives and the 1802.
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.
1802 history in space:See this Web page for details about the COSMAC in space. Please note: 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. In fact, the COSMAC was likely the first microprocessor to operate an Earth-orbiting satellite. Read the linked document for details and primary references to confirm. Steve Gemeny, an active member of Yahoo's /groups.io cosmacelf group, contributed his first-hand information. He worked on a number of NASA spacecraft projects at the Johns Hopkins Applied Physics Laboratory (JHU/APL). - Herb Johnson
Web links to other ELF 1802 sites:
User Manual For The Cdp1802 Cosmac Microprocessor Microcontroller
Many of these references were discussed in the cosmacelf group.
The EMMA 02 COSMAC Emulator emulates *many* 1802 boards and systems;
Mike Riley's Elf Web page with micro/Elf and pico/Elf designs and considerable software;
Elf 2000 from Spare Time Gizmos (not in production);
use of the ELF2K ROM on the 1802 M/S card;
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 languagedeveloped by COSMAC developer Joseph Weisbecker. Apparently CHIP-8 was reimplemented numerous times in the decades since the COSMAC ELF, for graphicalcalculators; then as a general emulator in the 1990's. It seems to be one of the subcultures within vintage videogaming culture.
Contact information for Herb Johnson:This page and edited content is copyright Herb Johnson (c) 2020. Contact Herb at www.retrotechnology.com, an email address is available on that page..
AUGUST 1976
[33] [34] [35] [36] [37] [38]
[Part 1] [Part 2] [Part 3] [Part 4]
Fig. 4. Complete circuit for the Elf computer. Identified connections on the left go to the 'front panel' with the eight data switches. The remaining can be left 'floating' at 1802, or tied to terminal strip.PARTS LIST
| 5½' x 2' (14 x 5.1cm) piece of thin aluminum; ¾' x 3/8' (19.1 x 9.5 cm) pine for chassis rails; 14-pin IC sockets (4); 16-pin IC sockets (3); 22-pin IC sockets (2); 40-pin IC socket; connector for power supply; 9-volt, 350-mA dc power source; 1¼' x ¾' x 1/8' (31.8 x 19.1 x 3.2 mm) piece of aluminum; dry-transfer lettering kit; machine and wood hardware; hookup wire; solder; etc. Note: the CDP1802 COSMAC microprocessor chip is available from any RCA parts distributor as is the COSMAC user manual. |
automatically incremented so that it points to the next instruction to be fetched. Branch instructions can be used to change the address in the program counter to permit jumping (branching) to a different part of the program when desired. The digit in the 4-bit P register specifies which 16-bit general-purpose register is being used as the program counter.
Timing Sequence. Since many of the 1802 microprocessor's instructions are only one-byte long and require two machine cycles, the first cycle is always an instruction fetch, or memory read. The fetched instruction is executed during the next machine cycle, which could be a memory-read memory-write, or register-transfer type of cycle.
Program execution always consists of a sequence of fetch-execute cycles, and the two SC0 and SC1 lines (see Fig. 4 and Fig. 5) indicate what type of cycle is being performed according to the following criteria:| SC1 | SC0 | Type of Machine Cycle |
|---|---|---|
| 0 | 0 | instruction fetch |
| 0 | 1 | instruction execute |
| 1 | 0 | DMA in/out |
| 1 | 1 | interrupt |
Circuit timing is shown in Fig. 6.
[33] [34] [35] [36] [37] [38][Part 1] [Part 2] [Part 3] [Part 4]
35 AUGUST 1976