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Apple-1

I am no longer active in this hobby for the foreseeable future. 
I will no longer maintain or update the website, but I will leave it accessible to the web for as long as possible (years).

 

Mark-8 Minicomputer
Apple-1
MOS Kim-1
V C F
Imsai 8080
Kenbak-1
TV Typewriter
LSI ADM-3A
ASR-33
The Digital Group

My Collection
HP-01
Test Equipment
Model Rocketry

 
Home Made Apple-1

Back around 1977, I ran across plans by Steve Wozniak, AKA Woz, for the Apple-1 computer. I had the chips, and the time, so why not? This is what I built. I no longer have the set of plans I used, I have no idea what became of them. The project took me about a month to complete, and though I populated the board with chips and made sections of it run perfectly, as a whole, it didn't work well, and I soon abandoned the project. If I recall, I suspected the problems were with the surplus dynamic RAMs, but looking back on it, I also took some shortcuts in my construction for lack of cash to do it right. For example, all of the parts were used or surplus (even the IC sockets). I did make an off board 1K static RAM board that worked better, but I had to rob the chips from my Digital Group computer to populate it, and I valued that computer far more. It was fun while it lasted.
 

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Homebrew Apple 1 Computer, circa 1977.
 

The Circuit

The Apple-1 was an ingenious design that was very unique for the day. Based on the MOS Technology 6502, it was probably the first hobby computer to ever be designed by a real electronics engineer.

The Apple-1 used dynamic RAM, a far more economical memory than static RAM, but very hard to use. Dynamic RAM required "refreshing" every 2 ms. This was a heavy burden for an early microprocessor, requiring special timing and controllers to stop or pause the processor long enough to complete a refresh cycle 500 times a second. Almost no one could make it work the first time. Miss a beat, and you lose most or all your data. (I remember MITS had many problems with their attempt, and although the Digital Group version worked fine, a few modifications were required to the CPU and other boards to make it work.)

Woz made it work. The Apple-1 used the same clock signal to refresh the RAM, out clock the video and run the processor. It worked perfectly, and made history.

My home built version had several other differences from the Woz's Apple-1, I already had a nice video card as part of my Digital Group system, so I didn't build one on board. I also didn't have access to the ROM listings, so I made my own boot ROM to load programs by keyboard. I also made other modifications, but I no longer remember what they were or why I made them...

That's all I can remember about the homebrew!
 

The Replicas

There have been a number of Apple-1 replicas built in recent years, the Replica-1 built by Vince Briel is probably the most available of all Apple-1 replicas. I even took home a Replica-1 as a prize at the VCF a few years ago. Sweet.

In 2005, Steve Gabaly of Apalacia, NY, made the most faithful Apple-1 replica to date. Steve owned an Apple-1, and used it as a model to make a near photographical and functional reproduction of the Apple-1. The following are photos of two that I built, the first was sold to Richard Garriott in 2005, the other is one that I still have. I also have one kit which is unfinished and not shown here.
 

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Apple-1 Replica, copied by Steve Gabaly, built by me
 

This Apple 1 was sold to Richard Garriott 12/05 

 


Video of Apple-1 in operation - 8.5 Meg

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Finished Apple-1 without Plexiglas
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My second Apple-1

Below is my latest Apple 1, built in similar fashion to the Richard Garriott Apple 1 above, but in this version, the keyboard is detached. This version also has a raised platform for the power transformers, allowing the interconnection wiring to remain mostly hidden, and wider sides with drilled holes for the eventual addition of a full enclosure to be made of tempered glass or plastic... The Garriott Apple 1 had a single 1/4" plastic plate to cover the computer, and although it looked nice, I was not completely happy with that approach, as it left the sides exposed to wandering fingers. I also prefer the detached keyboard for display purposes. Cassette interface is visible in a few photos.

 

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Copyright 2008 Bryan's Old Computers
Last modified:
October 16, 2009