Re: [midatlanticretro] I finally finished my Obtronix Apple 1 reproduction!
I did some looking, and found a chip called AM2808C,
which you can buy at Anchor Electronics for $2.95
It's a 1Kx8 dynamic shift register in an 8-pin package.
Uses a two-phase clock just like the Signetics part, and +/-5V.
The pinout is a little different from the 2504V, but if you
want to make a little adapter, it looks like it might work.
I found the data sheet for the AM2808 chip if you want it.
--- On Sun, 7/13/08, us21090 <us21090@...> wrote:
From: us21090 <us21090@...>
Subject: [midatlanticretro] I finally finished my Obtronix Apple 1 reproduction!
Date: Sunday, July 13, 2008, 3:33 PM
I finally finished my Obtronix Apple 1 reproduction!
Actually, building the Apple 1 didn't take much time at all! It was
the custom work on the mounting board, the curved and angled plastic
leg brackets and, and ...
I uploaded photos of it to
http://www.vintage- computer. com/vcforum/ album.php? u=6611
I also have a request:
My Obtronix Apple 1 reproduction had a bad Signetics 2504v. I don't
think it was DOA (I believe it just "developed" the problem recently).
The Signetics 2504v is a 1024-bit dynamic shift register, 8-pin dip.
It's used here to as part of the display control. The problem I saw
was odd numbers (1,3,5,7,9,A, C,E) in every other screen column were
displayed as the preceding ASCII character (0,2,4,6,8,@ ,B,D). Data
from the keyboard was stored correctly in main RAM. The video memory
problem just displayed it incorrectly.
Anyway, does anyone have a source of a Signetics 2504v? Or possibly,
is there other junk-hardware- for-parts that I could pull a 2504v?