Say, if you don't want to read my nostalgic drivel but need some Sym-1 resources, click the link to go right there. Or you can go straight to the sections on BASIC programming or on the cc65 C Compiler for the Sym-1. But if you're feeling nostalgic yourself, read on.

In 1978, we were paying about 75¢ a gallon for gas. We had just celebrated the bicentennial, and were still wowing over Peter Frampton's talk-box guitar on "Do You Feel Like We Do." Intel Corporation had invented the microprocessor just seven short years ago. Their 8080 was an excellent chip, but the failure rate was high, so rejects drove up costs to around $250 per chip. In volume, a manufacturer could negotiate the price down to under a hundred bucks, but that was still fairly expensive.

Enter the 6502 from MOS Technologies. It was a low-cost microprocessor, mainly because the fabrication technology increased yield. They had a much lower rejection rate, and cost per chip was much lower. It also required only a single voltage power supply. So manufacturers embraced the chip and put it in computers like the Apple, the Pet, the KIM-1 and the VIM-1, later renamed Sym-1.

VIM-1

external keypad and display

keypad and display wiring

The Apple and the Pet were more like what was to become personal computers. The KIM-1 and the Sym-1 were more microcontrollers, much like what the Raspberry Pi is today. The KIM-1 and Sym-1 were actually designed to showcase chips from their respective manufacturers, MOS Technologies and Synertek.

What I liked about the Sym-1 was that it had a lot of I/O lines, so it could sense and control a lot of devices. And its monitor ROM had several useful functions that were well-documented, so programming was made simpler by taking advantage of the built-in software. Further, it had Microsoft BASIC on ROM as well as a nice assembler/editor.

I got my first Sym-1 in 1978, and it was before they changed the name so the silkscreen on the PCB and the packaging labeled it as VIM. They later changed the name to what it is commonly known as, the Sym-1. Mine had the Microsoft 8K BASIC ROM and 4kB of RAM. When Synertek introduced the v.1.1 monitor ROM, I purchased it so I have both v.1.0 and v.1.1 ROMs. The only real difference was in the tape routines, and mine worked well with v.1.0, so it didn't change much for me.

In the 1970s and early 1980s, minicomputers ran business and microprocessors were used just for specialized controllers and what-not. There were, as I mentioned earlier, several really cool general-purpose microcomputer systems but the public still perceived computers as room-filling beasts that spanned several 6-foot-tall, 19-inch-wide cabinets and using disk drives as big as washing machines.

But through the 1980s and 1990s, that all changed. The minicomputers were slowly replaced by more and more capable microcomputers. The first step in the evolution was microcomputer workstations that acted both as terminals to minicomputers and as stand-alone systems that could do word processing and general applications. Then several microcomputers were networked, and businesses started becoming less reliant on minicomputers. Eventually, even powerful servers were made using microprocessors of ever-increasing computing power, memory and speed.

As those years passed, eventually I used my Sym-1 less and less. It was like Puff the Magic Dragon for me.

I found myself longing for those days in the summer of 2020, so I dusted off my old Sym-1, hooked it up to 5v and a terminal emulator and fired it up. As if the last 40 years were just a single night, the system gave a Beep. I pressed "Q" and it returned the "." prompt. I started BASIC by typing "j 0" and got the old familiar message:

.j 0
MEMORY SIZE?
WIDTH?

 3583 BYTES FREE

BASIC V1.1
COPYRIGHT 1978 SYNERTEK SYSTEMS CORP.

Super groovy cool!

I started thinkin' I should add some memory. These days, large memory is cheap so I set about looking. What I found was two things:

1. You can still get 2114 chips - both new and old stock - but the new chips have about 50% failure rate. I expect they're not testing them after they are made, and defects are slipping (pouring) through. So if you buy new 2114 RAM chips, buy twice as many as you need.

2. Corsham Technologies' Bob Applegate sells an excellent memory card for the Sym-1. So forget about the 2114 chips and buy a memory card from CorshamTech.com. He also sells edge connectors, both for power and expansion. Bob is a great guy, so be sure to shop there!

CorshamTech RAM card

Sym-1, after the silkscreen change to SYM

You can click on any picture on this page to get a closer look.

Check out Bob's memory boards. You'll notice they have small DIP switches, which are really convenient. They let you enable or disable RAM in 4K blocks. This is great because you can select or deselect the first 4K, depending on whether or not you populated your Sym-1 with 2114 chips. You can also select the whole B000-FFFF range if you don't have BASIC and RAE ROMs installed, which will allow you to load them from tape. I've provided ROM images for both BASIC and RAE as WAV files, loadable through the tape input, at the resources section below.

After installing the CorshamTech memory board, my system was huge! Enough memory to run the old Star Trek game that was so popular in the 1970s! It's in the resources section below, by the way. Just click the links for the "BASIC programs."

.j 0
MEMORY SIZE?
WIDTH?

 32255 BYTES FREE

BASIC V1.1
COPYRIGHT 1978 SYNERTEK SYSTEMS CORP.

When I was searching for stuff for my Sym-1, I found one on eBay and I bid on it. Ended up getting the one pictured right beside the CorshamTech memory board, shown above. It looked to me like it had never been used. Even the box was pristine. Compared to the box mine came in - which has "been around" - this one looks brand new. It also shows the name change from VIM to SYM:

VIM-1 and SYM-1 packaging, side view

VIM-1 and SYM-1 packaging, top view

If you look closely at the Sym-1 photo above, you'll see a modern part in the U20 ROM socket where the Monitor ROM should be. This is a 2332 replacement part with a Monitor 1.1 image in it. The Sym-1 from eBay came with Monitor v.1.0 - which is fine with me - but still, I wanted to use the binary images to make a new ROM for it. However, 2332 chips and programmers have become scarce and expensive. So I found another alternative.

I found a guy named Tony that runs a website called Vintage-Computers.it, which is a computer repair site in Rome. What's really neat is he makes a product called MultiROM as a replacement for 2332 and 2364 ROM chips. His MultiROM is based on a 27c512 mounted on a small board with 2332-compatible pinouts and it provides eight ROM images on one device, selectable by jumpers.

So I contacted Tony and provided ROM images for Monitor 1.1, BASIC and RAE as five 4kB blocks. I ordered five of these chips setup to emulate 2332 ROMs, so that each can be jumpered for its intended use - Monitor at 8000, BASIC at C000, BASIC at D000, RAE at B000 and RAE at E000. I also ordered a MultiROM jumpered to emulate a 2364 with BASIC as a single 8K block from C000-DFFF. The Sym-1 can be jumpered for either kind of ROM chip, but I found that early boards were sent out jumpered for 4K ROMs and later boards were jumpered for 8K ROMs. It's easy enough to change the jumpers, but it's also nice to have a variety of ROMs, suitable for either application.

I also ordered another memory board from CorshamTech for the new Sym-1. If you look closely at the Corsham memory board photo above, you'll notice that two of the boards have switches to select B000-FFFF but two of the boards have the C000-DFFF range disabled. That's because I run two of those boards on the new Sym-1, and I haven't populated the ROM sockets with BASIC. Instead, I load BASIC from tape (actually, a digital audio recorder/player) when I want to use it.

Funny aside - using a digital audio device to record and playback data files - so the Sym-1 digitizes the sound to make analog and the digital recorder samples the analog to make it digital again. Goofy. But it works, and it's easy. Makes me think of a microprocessor controlled vacuum tube, but that's another inside joke from a long, long time ago...

The CorshamTech boards come with the edge connector soldered on, and it's made to mount in the same plane as the Sym-1 "motherboard." But I decided to get a Metcase enclosure for my Syms, and it doesn't have quite enough depth for that. So I ordered another pair of memory boards from CorshamTech sans edge connectors. I soldered 'em on 90° so I could stand the memory board upright. Fits in the case that way. That's also why I have the detached keypad and the display on my original Sym, so it can mount to the front panel. I socketed the 7-segment displays and installed a SIP keyboard connector to connect them.

Sym-1 System with Front Panel Keypad and Display

Sym-1 Cabinet Internal Layout

I used the Metcase M5503110, which is light gray and just large enough to mount the Sym-1, memory board and power supply. I also installed a board that has a couple of little audio amplifiers, mostly so I could adjust the levels for a variety of tape and digital audio recorders. The blue LEDs aren't "period correct" but they nicely complement the blue in the Synertek logo. I think if blue LEDs were available back when Synertek was around they would have used 'em. I had panels made at Ideal Specialty, in Tulsa. The job number was K-22971, and that can be used to identify the drawings, if you want to have a similar case made for your Sym-1.

Sym-1 System without Front Panel Keypad and Display

Sym-1 Cabinet Rear Panel

As you can see, I had two cabinets made. One system has a keypad and display mounted on the front panel, and one does not. Both systems used the same rear-panel. You might also notice the vertically mounted Corsham memory board. There is plenty of space between it and the rear panel of the cabinet, but I still glued on a piece of 40mil PVC plastic sheet material, sitting just behind the memory board. Never hurts to be safe.

To make it really fun, connect using a VT-100 clone based on the boards made by Geoff Graham and Peter Hizalev.

But the first Microsoft product was actually 8K BASIC. It was in all the popular microcomputers in the 1970s. They started off making it for the MITS Altair 8800 computer, which had an 8080 microprocessor. And when the 6502 became popular, Microsoft created a version for it. The Apple II, the Commodore Pet and the Sym-1 all had very similar versions of this 8K BASIC.

You can run simple BASIC programs with 4Kb of RAM, but a lot of the "really good programs" need more than that. One in particular that I always loved, was Star Trek. Any time I was at a computer club meeting where someone had a computer with more than 24Kb RAM, they'd be running that game. Just like you could expect to hear Led Zeppelin's "Stairway to Heaven" or Lynyrd Skynyrd's "Freebird" in every college dorm and at every party, if you went to a computer club meeting you would see Star Trek running on the head geek's computer.

So now, with the CorshamTech memory board, my Sym-1 could be propelled to the pinnacle of geekdom and run Star Trek.

The problem is there are a lot of versions of the game and most don't adhere to the 72 characters per line length limit. Some come close though. That's a problem with many of the popular BASIC programs - there wasn't a standard back then. Even the language was slightly different between platforms. You had Dartmouth BASIC, the original. Then you had Digital Equipment Corporation's PDP-11 BASIC and BASIC-PLUS. You had Data General's Business BASIC. Wang had their own BASIC. Basically, every platform had their own version of BASIC.

Microsoft's entry of 8K BASIC sort of standardized the microcomputer industry, simply because it was so common. But that was still just another version of BASIC, and the popular "BASIC Computer Games" was actually written for DEC BASIC, so some stuff worked on 8K BASIC and some stuff didn't.

So I set about finding all the BASIC programs I could find and seeing which would run on the Sym-1. Where I found line length past 72, I modified the program so it would fit. I usually just split the line into two lines. Sometimes, I needed to do a little more. But in most cases, the program is completely original. I've noted changes in a README.TXT file in the archive.

#include <stdio.h>;

void main (void)
{
   puts( "Hello World!" );
   return;
}

#include <stdio.h>;

void main (void)
{
   printf( "Hello World!\n" );
   return;
}

#include <stdio.h>;
#include <stdlib.h>;
#include <string.h>;

void main (void)
{
   char* buffer;
   int   heap_size;

   heap_size = _heapmaxavail();

   printf( "Heap available is %d bytes.\n", heap_size );

   buffer    = malloc( heap_size );
   memset( buffer, 0x00, sizeof(buffer) );

   if( buffer ) {
      puts( "Memory allocated." );
   }
   else {
      puts( "Couldn't allocate memory." );
   }

   return;
}