When I set out to build my Apple 1 Replica I wanted to recreate the one from the first advertisement. How do you think I did?
Recently I was bringing up an Apple 1 and I did the first thing I always do to do an initial checkout, which is run the Test Program from the Apple-1 Operation Manual. This is a very simple program that runs a loop that counts from 0x00 to 0xFF and prints each byte as an ASCII character. Here is the program:
0000 LDA #0
0003 JSR ECHO
0008 JMP $0002
This time when I brought up the Apple 1 I saw the following output:
The last time I had run this program, I had run it on an emulator and seen the following:
Remembering how the output looked I thought there was a problem with my Apple 1. After further investigation I found the answer in the Apple 1 schematics.
It turns out that character output is tied to RD6 or RD7. This was overlooked in every Apple 1 emulator that I have looked at.
Recently I wrote an Application for iOS devices that can be used to load Apple 1 software through the cassette interface. One key benefit to this application is that is shows load and verify instructions for each program. I’m currently in the process of getting this added to the App Store.
Today I built up Mike Willegal‘s Apple Cassette Interface for the Apple 1. Previously I was using the Obtronix interface, however Mike’s board is a more accure reproduction.
Here is a video demoing Mike Willegal‘s Brain Board. In the demo I load Blackjack for the Apple 1 from cassette.
The most distinct chip on an original Apple 1 is definitely the MOS 6502. This chip originally came in a white ceramic package, and that is what shipped with the original Apple 1 computers. When I decided to build my replica using original parts, I set out to find this chip. As it turns out, this is a relatively sought after chip. They rarely come up for sale, and when they do they can claim hundreds of dollars. After a few months of searching I finally found one. What I did not know when I started searching was that this chip actually came in three different variations of the white ceramic packaging. The Apple 1 computer used a package with no external ground strap. This was the very first package used on the MOS 6502. Later MOS shipped two white 6502’s with an external ground strap. One had a centered strap, the other ran along the edge. The original packaging is the most rare, and took me almost a year to acquire.
Today I received a bunch of Interface Age magazines in the mail. This magazine carried the very first Apple 1 advertisement in July of 1976 as well as an article about the new company. In September the magazine printed a 6502 Disassembler by Woz and Allen Baum, and in October an article by Steve Jobs about connecting the SWTPC PR-40.