Synertek SYM Model 1
Price:US $239
CPU:Synertek 6502 @1MHz
RAM:1K, 4K max on-board
Ports:Two edge-card 8-bit ports
Display:6-digit LED
Storage:TTY, audio cassette
OS:"Monitor" in ROM

The Synertek SYM Model 1 computer is "one of the most versatile and sophisticated single-board computers available", "an ideal introduction to the expanding world of microprocessor technology as well as a powerful development tool for design of microcomputer-based systems."

It is a simple computer systems made from basic hardware and software components. Best uses include learning to program, simple machine control, and sensor monitoring.

The SYM-1 is similar to the KIM-1, another single board computer (SBC) which was released by MOS two years earlier, in 1976.

While more advanced than the KIM-1, the SYM-1 was designed to use the same peripheral cards and data storage protocols for compatibility reasons.

Its advantages over the KIM-1 lie in its expandability to 4K user RAM on-board, the provision for up to 8K of ROM or EPROM on-board, a lot more I/O lines, an improved Monitor program, higher cassette tape I/O rates, and a number of other nice little features.

Unless an external terminal is hooked-up, the only way of interacting with the system is with the 28-key keypad and the 6-digit LED display.

Four ROM sockets are available for permanent program storage. The "SuperMon" monitor program is in one ROM, BASIC or other applications can be installed in the others.
-Upon boot-up, with an optional terminal hooked-up, BASIC says:
No sign of Microsoft anywhere!

Well, not necessarily - Bonnie Sullivan writes:
I worked on software for the SYM-1 project, and I can add some details.

The software was written by Nelson Edwards and students in Walla Walla. They hand-assembled the 6502 code.

There was an option to have the SYM-1 with Microsoft Basic. Bill Gates himself came to see us and provided the Basic. He was arrogant, baby-faced, and he wrote buggy code, then refused to believe that it didn't work.

I think that he assembled it with macros in a PDP-10 assembler. We would provide him with hardware specs, he would customize Basic, send us the code, we would burn an EPROM, and it wouldn't work. "That's impossible!", he would say, despite the fact that he didn't have the hardware, so he hadn't tested it.

The SYM-1 has a cassette I/O for data storage, at a whopping 8 bytes/sec (KIM compatible) or 185 bytes/sec (high-speed mode) transfer rate.

There is also the TTY I/O for a terminal interface. Built-in hardware allows for a oscilloscope display with 32 characters/line, similar to a CRT terminal.

Bonnie adds:
It was a clever output called the "two bit interface." It was a circuit that generated a sawtooth ramp, with the ability to clamp the output to ground. You could use this to output a line of 32 characters to an oscilloscope (which we figured every SYM-1 user had on hand). "Two bit" because it had two bits of output, and because the circuitry cost about 25 cents.

Data storage includes audio cassette, TTY (hard copy output), and paper tape. A floppy drive can be used, but only with additional hardware. The on-board piezo-speaker 'beeps' when a key is pressed, or when directed by the program.

This particular SYM-1 has an expansion chassis with 5 additional slots for expansion cards.
In the lower slot is a memory card - "The Computerist, Copyright 1980". It has 16K RAM installed (NS MM5290 X 8), with room for an additonal 16K.

It also has two 6522 VIA (Versatile Interface Adapter) chips, and sockets for addition ROMs. This is apparently more than just a memory expansion card.

From the Synertek SYM-1 manual:
Twenty Important Cassette Recording Guidelines
  1. Use high quality tape (Maxell UD or equivelent).
  2. Use shortest tapes possible. You can shorten tapes to several minutes in length if you enjoy splicing.
  3. Use shielded cable between your computer and the cassette recorder.
  4. Keep heads and pinch rollers clean.
  5. Keep heads aligned for tape interchangability.
  6. Avoid recording too close to beginning of tape.
  7. Make sure cassette is properly seated in recorder.
  8. If you have trouble with a cassette, try another. You can have a bad spot on tape or a warped cassette.
  9. Highest setting of tone control is usually best.
  10. A dirty recorder volume control can cause tape dropouts.
  11. Make sure cassette connection plugs make good contact.
  12. Rewind cassette before removing them from recorder.
  13. Store cassette in dust-proof containers.
  14. Avoid exposing cassettes to heat or magnetic fields.
  15. Before recording, wind cassette to one end and fully rewind.
  16. Cassette recorders will give you problems once in a while (They don't like certain cassettes, etc.). If one gives you problems most of the time, replace it.
  17. Make sure that MIKE plug is connected before recording. On most recorder the TAPE light will glow while recording.
  18. You may have to record with the EAR plug out for some tape recorders.
  19. Always use AC adapter with recorder for best results.
  20. When a tone control is available, adjust it to the highest possible setting (maximum treble).

       More is always better!

Related Links

  • Synertek SYM-1 Resources
  • Synertek Systems SYM-1 Docs (PDF) from Rich's classic computing lab
  • Dallas' SYM-1 Pages

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