Sym-1 A 6502 Phoenix!

A simple filing system for a Sym-1 with the Resident Assembler and Editor

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Hi Hackers everywhere,
This project describes how to add a simple filing system to a Sym-1 board that has RAE installed in ROM or EPROM or EEPROM. It has several stages any of which might be of interest to either Sym-1 owners directly, or other 6502 retro computers, and possibly to the new hackers who are bread-boarding incredibly impressive 6502 systems. Possibly other processors who might like to build a simple filing system add on may find the general principles helpful.

The project's description has been broken up onto several Hackaday pages that will be linked back to this page as a summary source. Check the Log of associated pages below. While not complete yet, you may find some interesting, even entertaining reading, good luck!!

Retro computing is a good reminder of how far things have improved, but go back there? I have yet to own any computer that I have felt that I have exhausted all possibilities to learn and interact with it. My work as a teacher for 36 years usually mandated that we move the children to the next stage of technology to keep then students as up to date as possible. This inevitably meant that quite capable designs were declared "old fashioned" well before all that they offered were explored. I am returning here to the second SBC I purchased around 1980, the Sym-1 by Synertek. Not to turn the world around but just savour again the thrill of working with a great design that promised so much, and that I found not enough time to explore.

I bought another Sym-1 around 2017 and wanted to use the RAE, the Resident Assembler and Editor as the main software on it. I had always enjoyed Assembly Language and was yearning to not do it by hand this time, but to use an assembler. The rise of the Arduino systems had drawn me back to bits and bytes, and made me remember just what these retro machines offered.

To this end I first had to get the Sym-1 to a convenient level of operation. being familiar with the versatile design, I set about exploring what could be done. Here is a simple list of the progression of the project.

1. Power Supply: 5V LED supply

2. Expand the onboard RAM

3. EPROM Programmer

4. Expand RAM off the board to 32k or more

5. Soft load major ROM images

6. Use 2764 (8kx8b) EPROMS

7. SD Card storage and retrieval.

These will be explained and outlined in separate Hackaday Pages, as not all parts will interest everybody, and will make the story a bit more modular. The files developed are linked to this page as I can't see how to link then to the relevant Hackaday Pages. This will also provide a short cut for those who don't need my explanations of what needs to be done.

Given the number of new designs for retro 6502 systems (especially those amazing breadboard constructions) they could do well to try to incorporate the RAE as their main language support. It provides very open ended programming capability, and given the Arduino IDE today, well ahead of it time. I am not sure what would be required to get the Sym-1 monitor and RAE to transfer to a Bread Board Build for a 6502, but I hope that my work will show a filing system is well within easy reach.


MS BASIC in Synertek Paper Tape Format. Use .LP to load it into RAM at 300Baud and Python Terminal (be prepared to wait 20mins or so).

ptape - 22.00 kB - 09/22/2021 at 07:54



RAE in Synertek Paper Tape Format, Use .LP to load it into RAM at 300Baud and Python Terminal (be prepared to wait 20mins or so).

ptape - 22.00 kB - 09/22/2021 at 07:48



RAE with the order of the 4kB blocks reversed so no inverter is required on A12 to the 2764 EPROM (See notes)

x-extension-bin - 8.00 kB - 09/22/2021 at 07:45



An Arduino Mega2560 sketch to allow MFS V18 access to SD card as a filing system. Heavily commented for debugging.

ino - 12.70 kB - 09/22/2021 at 07:34



Latest Sym Monitor ROM Ver 1.1 4kB originally distributed by Synertek, provided so you can merge your own extensions to it as well. Go for it!

rom - 4.00 kB - 09/17/2021 at 02:55


View all 10 files

  • 1 × Sym-1 SBC Synertek c: 1976 A 6502 prototyping system
  • 1 × Arduino Mega 2560
  • 1 × Arduino WiFi and SD Card interface Adafruit CC3000 WiFi shield V 1
  • 1 × Hook Up wires Cut up solderless breadboard connectors to solder to Sym-1 plug, and pins for Mega
  • 3 × 44 Pin Socket 805-44P 3.96mm pitch 22 by 2 double sided socket

View all 10 components

View project log

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