The VIP2K
A Tribute to the 1977 RCA VIP Home Computer

Let's go back... Way back to 1976, at the dawn of the microcomputer revolution. Before the Apple II, Commodore PET, and Atari home computers, Joe Weisbecker designed the RCA VIP. It was an elegantly simple home computer that was easy to learn and fun to use. That's an original VIP on top of the monitor in the photo.

He spent years testing and perfecting the design with FRED (Friendly Recreational Educational Device), System 0, and the Microtutor, until the VIP itself was ready. It had an RCA 1802 microprocessor, 2K (or optionally 4K) of RAM, a monitor program in ROM, a 16-key hex keypad, a 64x128 pixel graphics video display, and a serial port to load/save its programs on cassette tapes. It used 1/4 the parts of its rivals, and was far less expensive. It should have been a raging success! So what went wrong? RCA had been "burned" by its failures in the mainframe computer market, so Management was dead set against entering the risky microcomputer arena. They dragged their feet, and never gave the VIP the chance it deserved. It got left at the starting line, while others raced ahead.

For the 40th anniversary of the VIP, we made a new version you can build yourself. That's it at the bottom of the photo, hiding under its tiny keyboard! The battery box is at the right, with four AA cells to power it. Our version has the same 1802 microprocessor, but with significant upgrades in speed, memory, and features:

• 1802 microprocessor running at 4 MHz
• 32K of RAM
• 32K of ROM with monitor, BASIC, and CHIP8
• NTSC or PAL video displays 24 lines of 24 characters, 192x192 pixel graphics
• 43-key full ASCII keyboard
• TTL serial I/O at 9600 baud
• built entirely with common vintage parts and thru-hole technology
• ...and it all fits in a 3.5" x 2" x 0.75" Altoids tin!

The computer is based on the COSMAC Elf and 1802 Membership Card, so the same software works with little or no change. The kit comes with the MCSMP20 Monitor, RCA BASIC3, and CHIP8 programming language all in ROM. They use the VIP2K's keyboard and video for user input and output, and the serial port for load/save.

The manual is pretty basic, but should be enough if you're a skilled kit builder. Bare boards are available, and the parts are all generic and easy to get (no rare, expensive, or custom parts); but you'll need to be able to program your own EPROMs. Or order a kit, which comes with everything, including EPROMs programmed with the latest software.

31 Oct 2022: The VIP2K rev.C kit is now available!

VIP2K rev.C Bare Boards -- $18.02. Includes both PC boards and the manual with schematic, parts list, and parts sources.

VIP2K rev.C Complete Kit -- $50.00. PC boards, manual, tested 4 MHz 1802, programmed EPROMs, and all parts that go on the boards. Select NTSC or PAL:

Select NTSC or PAL: NTSC (US 60Hz video) PAL (European 50Hz video)

Need more information?

• Documentation:
  • VIP2K rev.C manual in PDF format for the current version.
  • VIP2K rev.B assembly notes in PDF format for the previous version.
  • VIP2K rev.A assembly notes in PDF format for the first version.
  • VIP2K Key sequences to produce all of the ASCII codes.
  • VIP2K memory map for writing your own programs.
  • VIP2K video map for writing data to screen memory.
  • MCSMP20 Quicknotes for using the Monitor program.
  • BASIC3 User Manual in PDF format.
  • RCA VIP CDP18S711 Instruction Manual for RCA's original VIP, includes 20 programs and games.
• EPROMs:
  • vip2k15.hex MCSMP20 Monitor, RCA BASIC3, and CHIP8, all in a single 32K EPROM. Burn this HEX file into a 27C256 and install it at U2. Released 11 Sep 2019.
  • 2716ntsc.hex The VIP2K state machine EPROM for NTSC (60Hz US) video. Burn this HEX file into a 27C16 (2K EPROM) and install at U7. Here are the ASM and PRN source files for this program. Released 11 Nov 2018.
  • 2716-pal.hex The VIP2K state machine EPROM for PAL (50Hz European) video. Burn this HEX file into a 27C16 (2K EPROM) and install at U7. Here are the ASM and PRN source files. Released 1 Jun 2019.
• Programs:
  
  • VIP2K TV Typewriter demo program. Type keys on the keyboard and they get displayed on the screen. New line=NL (CRLF), cursor up=^u, down=^d, left=^l, right=^r, home=^h, and clear screen=^c. Hold down a key to auto-repeat. Burn this HEX file into a 27C256 (32K EPROM) for U2. Here are the ASM, PRN, and README files, to learn how to write to VIP2K video.
  • Star Trek "Enterprise" image from the 1978 Popular Electronics "Pixie graphics" article, in BASIC3 PLOAD format.
• CHIP8 Interpreter:
  • CHIP8 games sampler in a ZIP file.
  • COSMAC VIP Game Manual vol.1 with 16 more CHIP8 games.
  • COSMAC VIP Game Manual vol.2 with another batch of CHIP8 games.
  • Octojam is an annual CHIP-8 game contest, with lots of past entries.
  • Instructions for loading and running CHIP8.
  • Source code for Marcel van Tongeren's CHIP8 interpreter for the VIP2K, in ASM format.
  • CHIP8 IDE for developing and testing CHIP8 programs on modern PCs.

Here is a photo of it in operation, displaying the ELF's iconic Star Trek Enterprise image, and the BASIC program to produce it. The current VIP2K14 programs expect uppercase input, so the keyboard assumes uppercase (and SHIFT produces lowercase). Shift+key, Control+key, and Shift+Control+key functions can produce all ASCII characters. For example, ^1 is ESC, ^2 comma, ^3 semicolon, etc. VIP2K Key sequences has the entire map.

CHIP8 was written for the VIP by Joe Weisbecker, and documented in the Dec 1978 issue of Byte Magazine article "An Easy Programming System". It's an amazing language; an interpreter like BASIC, but small and fast like machine code. It is optimized for creating animated bitmap screen images with extremely low CPU speed and memory requirements, typical of the computers of the time. CHIP8 was ported to many other computers, and hundreds of programs and games were written in it. A CHIP8 community is still active today, holding annual programming contests (search Google for OCTOJAM).

The project is still evolving. The next goal is a serial terminal program, to use the VIP2K as a data terminal for other small computers. If you have any ideas, let us know!

The current version is now rev.C. It has an improved speaker output, power-on reset circuit, a RESET key on the keyboard, and a Caps Lock function and LED.

Here are the known bugs (and fixes) on the earlier rev.A PC board:

• U11 pin 15 is high: It should be low. Cut the trace between U11 pin 15-16, and connect pin 15 to GND instead.
• Video bit D0 may be narrow or not displayed at all. Add a 3300pF capacitor from U11 pin 1 to GND.
• The program may not start automatically at power-on or reset. This happens if video interrupts and DMAs are "on" before the interrupt handler and DMA pointer get initialized. The VIP2K14 ROM improved, but didn't eliminate this. The work-around is to power-up or reset again until it catches INT and DMA off. Another is to add a 1N4148 diode; anode to TVOFF (U9 pin 9), cathode to /CLEAR (1802 pin 3).
• Early version HEX files assumed that unprogrammed locations in the EPROMs would be FF hex. Some EPROM programmers will instead program 00's or "garbage" in unprogrammed locations. This caused strange bugs in the programs! Clear your EPROM programmer's memory to FF before loading the hex file, or use our current hex files (above) to fix this.

Marcel van Tongeren added the VIP2K to his excellent EMMA 1802 emulator. This will make it a *lot* easier to try and test software ideas.

Walter Miraglia 3D printed some lovely little cases for his VIP2K. The picture at left shows one with a tiny LCD monitor sitting on top. He has the files for it on Thingiverse.

Tomihisa Sakai produced a blog page on his VIP2K. It's in Japanese, but Herb Johnson made a quick translation of it here.

Paul Schmidt (youtuuba) made a detailed Youtube video of a pre-production VIP2K. Check it out here. He also made a nice keyboard overlay (pictured above).

Chuck Yakym and Marcel van Tongeren added PAL (50Hz) support for European and Far East TV monitors. Please specify PAL when you order the kit, or download the 2716-pal.hex file (above) to make your own EPROM.