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Interesting piece of history of the Mark 8

per

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Jan 21, 2008
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Very interesting read.

I recently got into HAM radio, and our club apparently have two 8008-1's in the legacy chip shelf. While the Mark-8 is very early design, and uses certain chips that's difficult to come by nowdays, I was thinking about the posibility to design an 8008 computer using more modern and readily available TTL components.
 

mwillegal

Experienced Member
Joined
May 27, 2008
Messages
233
It's been done : http://juliepalooza.8m.com/sl/scel.htm
Or you may consider a true SCELBI reproduction - it's expensive to do, but there really aren't any hard to find parts in the mix:http://www.willegal.net/scelbi/the8008andScelbi.html

Regards,
Mike Willegal
KC1CKV

PS
Byte published an 8008 morse code encoder/decoder program back in the day.

Very interesting read.

I recently got into HAM radio, and our club apparently have two 8008-1's in the legacy chip shelf. While the Mark-8 is very early design, and uses certain chips that's difficult to come by nowdays, I was thinking about the posibility to design an 8008 computer using more modern and readily available TTL components.
 

per

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Joined
Jan 21, 2008
Messages
3,006
Location
Western Norway
I do notice that many of the early 8008 computers use a whole bunch of dual not gates for propagation delays on the CPU board, while a more recent design; http://www.8008chron.com/ , gets away with only a GAL, some 74LS245/74LS373 (for demuxing/latching the bus) and some flip-flops. The only documented case I have seen where delays have been needed with 80's TTL speed parts and the 8008 is where the /RD and /WR signals gets to the RAM chips too fast.
 

mwillegal

Experienced Member
Joined
May 27, 2008
Messages
233
I do notice that many of the early 8008 computers use a whole bunch of dual not gates for propagation delays on the CPU board, while a more recent design; http://www.8008chron.com/ , gets away with only a GAL, some 74LS245/74LS373 (for demuxing/latching the bus) and some flip-flops. The only documented case I have seen where delays have been needed with 80's TTL speed parts and the 8008 is where the /RD and /WR signals gets to the RAM chips too fast.

the interface between the terminal and processor on the Apple 1 contains a 74123 one-shot that adds a few microseconds delay to the circuit.

regards,
Mike Willegal
 

8008guy

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Salt Lake City, Utah
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