|This is some shots of the first computer built by a single person that I know
of (me). It may not actually the first but its the first that I know
of. If anyone knows of an earlier one please email me [
This machine was built to learn about computers and because I met a guy who told
me with the up most assurance that a computer would never be built by a single
person - it was simply to complex. At the time I was working at Link
Singer building the first digital computer for a Link trainer. That
computer was huge, it filled several racks of equipment, and was one of the very
first built using integrated circuits. I remember that a dual flip-flop
from Motorola cost $9.00 and had to have a support chip for every 5 or six of
them. That machine itself was very interesting - but that's another story.
I decided to build this machine (it never had a name) to see if it could be
done. I started in 1971 and finished in 1976
All the hardware was scrounged from surplus yards or built from
scratch. The chips were bought from a guy that made a living from picking
up discarded chips from Intel, Motorola, and Fairchild, testing them and
reselling them. He also kited and sold one of the first computers concurrent
with the IMSI.
From the top of the rack down was:
- Dual audio tape recorders (I never got them running for digital).
- Paper tape reader. I built the case for it from a aluminum chassis.
- Control panel. At the time all computers had a control panel - none
do now. With the control panel I could enter the boot routine, inspect
individual memory cells and make changes as necessary.
- Below the shelf was a paper tape punch and below that a power supply
- The teletype is a surplus military that ran at a blazing 110 baud.
- behind the rack is my Heathkit ham radio with a kilowatt amplifier right
behind the teletype.
If you look closely at the table in the foreground holding the TTY you will
see a copy of the first Byte magazine. I still have a complete set of the
first year of Byte which makes for very interesting reading on a rainy day.
When I finally got this beast running I used it contact a second computer in
downtown San Diego over a 300 baud modem (not shown). That machine had an
assembler, written in Basic, for my machine. That way I could create a
program on the distant machine, assemble it and download the result to run on my
The first piece of software I wrote was a relocating linking loader for my
machine. With that I could fill up my 2K words of memory with what ever I
First Computer Inside
is a shot of the inside of the machine showing some of the circuit cards I built
and my trusty 'scope to keep it all running. Each card was built using 30
gage wire wrap wire. The card on the extender was a serial controller for
the teletype. It had one of the first UARTs for the actual bit
banging. The large white ribbon cables were used to interconnect the cards
on the front side. On the back plane side they were wire wrapped using 26
The card on the left side, showing five integrated circuits, is the CPU.
This card is the part of the compute still in existence and is shown below.
CPU card was built using SN74181 chips from Texas Instruments. This card
has four of them in the middle of the board with support TTL around them.
On the right side was a set of registers (16 of them) used to hold intermediate
results from the '181s as they did there work. The chips on the left side
were the bus buffers. The chips between the '181's were the high speed
look ahead carry logic.
This machine ran at a blazing 1 mHz clock rate but could do all the things
that any modern machine could do (plus some that they don't). Each
instruction was 16 bits wide and there were a total of 45 instructions.
Each instruction could be either indexed or indirect or both. The
instruction set was copied from a commercial mini-computer that I was using at
work (Philco/Ford at the time).
Memory for this machine was built from 1 K bit dynamic RAM and at the end I
had four cards with 1K X 8 on each card or a total of 2 K of 16 bit
memory. Since the chips were dynamic I had a refresh clock running
at all times. Without that they would forget what they were programmed with.
Booting this machine was a chore. I had to toggle in each of the 20 or
so instructions through the front panel each time I started up. This boot
strap program would load what ever program was in the paper tape reader.
That was the BBS software or the assembler or the loader or what ever I was
working on at the time.
I was able to get the machine to control my ham rig and send Radio Teletype
signals (RTTY) using it. I was also able to build one of the very first
bulletin board systems (BBS) in San Diego where the user would call into my home
phone and the modem would answer and give the remote user complete control of my
computer. I think this is the first time I started using the name Zeke for
a computer. The BBS was named Zeke and was well known in this area.
It used to tie up my home telephone for hours at a time. This was long
before AOL was a dream in anyone's eye.
After I got the whole thing running and was able to link and load the first
assembled program for the computer I broke out the wire cutters and cut the
whole thing to pieces. It had served its purpose and besides I had a new
toy to play with -
Zeke was a Z80 machine
that I built the first SETI search system on.