44 Pin Bus

The 44 Pin Bus Motherboard connects to the 44 pin edge connector on the Apple I and provides ten slots. Joe cut the board down to three slots and put three connectors on it due to space limitations in the cabinet.

Apple I - 44 pin bus 44 pin bus on Apple I

44 Pin Bus Advertisement

44 Bus Motherboard Advertisement

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44 pin bus catalog cover

Homebrew EPROM card

Apple I - eprom card back

Apple I - eprom card front Apple I - eprom card back 2

Joe writes:

"I built an EPROM card to use in the 44 pin bus in my Apple 1 computer. It had on it two 2716 EPROM's. The 2716 was a 2k memory chip. I had a new monitor and a dis-assembler on the chips. To use this card I had to first unplug the two Apple Proms on the motherboard. As you can see I did not solder the sockets, but wire wrapped the card instead."

Apple I - eprom card inserted


This board connected to the Apple 1 via the 44 Pin Bus and allowed S-100 cards to be connected.

The MOS Technology Kim-1 was a 6502 cpu based single-board computer with 1k of memory and a keypad for input.

The KIMSI allowed S-100 cards to be connected to the Kim-1. Connect this KIMSI card to the 44 Pin Bus card, and it was possible to use S-100 cards on the Apple I, as well.

KIMSI advert

KIMSI Connections

This paper shows the connections between the Apple 1 computer and the extension (expansion) card for the Kim-1 computer.

KIMISI Connections sheet

Drennan on the KIMSI

Richard Drennan
4590 Oberlin Avenue
Lorain, Ohio 44053

Dear Joe:

Once again I must apologize for taking so long to write. It seems
the older I get the lazier I get. Oh well.

I got the KIMSI board to work, but I get intermittent memory failiers
that have really bot me stumpped. To test the memory, I've using the
following program:

20 IF L>H THEN 10
30 J=170
40 FOR I= 1 TO 100
60 IF J=85 THEN 70 : J=85 : GOTO 80
70 J = 170
90 M= PEEK(K)
100 IF J=M THEN 130
120 END
150 END

This routine takes a long time to run, but if your memory passes it O.K.,
you can be pretty sure that the memory is adressing, reading and writing

I originally bought my APPLE I to have a micro processor to play games
on, but since I'm a compulsive tinkerer, The APPLE I is apart as much as
it is together. To solve this problem, I've bought an APPLE II. Now I've got
a computer that runs, and one I can tinker with. If I can copy the paddle
circuits used by the APPLE II and write some assembler routines to simulate
the APPLE II graphics comands, I should be able to write some "PONG" type
game for the APPLE I for use with the SWTP graphics board that I have
hooked to my APPLE I. I think games like "Breakout", "tennis", etc.
should be bossible. The APPLE II low resolution graphics mode is 40 X 47,
but my graphics board is a little better since it's resolution is 64 X 96.
The APPLE II graphics are in color, but my grpahics board is only black and

I don't know how you can set up a grid without some sort of graphics
board unless you plan to re-write it every time. If you are going to
re-write each time, you just build an array with the proper date, then
write teh board from the array (the HORTA program I sent you is a good
example of this techinique).

In order to convert my programs to the APPLE II, I listed all of them.
If you would like, I will see if I can make you a copy of all of them.

Wll, thats about it. If there is anything I can do, just write.
I'll try to write back quicker next time.