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"It needs just 930 logic gates (packed into 33 standard 7400-series ICs) to create a computer that beat 'complex' 1980s home computers like the VIC-20 in terms

"It needs just 930 logic gates (packed into 33 standard 7400-series ICs) to create a computer that beat 'complex' 1980s home computers like the VIC-20 in terms of both CPU power and graphics." Given that 7400 chips existed at the time, why did no contemporary microcomputer go this route? Would it just have been cost prohibitive?

tyingq 7y ago
There were commercial computers that did. The PDP-8, as one example (not 74xx, but similar). Edit: The Xerox Alto CPU was built with 74181 chips. Cost, power consumption, space, etc, are all disadvantages. I assume the Gigatron is using modern 74HCxx CMOS chips, which consume less power than the original 74xx TTL chips.
- dboreham 7y ago
  Yes HC didn't exist and 4000 CMOS was slow. Plus the pcb, assembly and test cost for 40 DIP packages is significant.
- ttldude 6y ago
  Typical discrete logics designs were much larger than the Gigatron. So they're not the same. Using 74LS the single board draws 2.5 W.
klodolph 7y ago
The short answer is that computers with CPUs made from 7400 series TTL existed, but they weren't "micro".
- tyingq 7y ago
  The Kenbak-1 might be considered an exception to the rule: http://www.kenbak-1.net/index.htm http://www.kenbak-1.net/index.htm
djmips 7y ago
930 logic gates + 1K of microcode ROM (so how many gate equivalent is 1K of ROM?) and it only runs 1/4 speed of a 6502.
xkriva11 7y ago
The simplicity of Gigatron is compensated by the large memory that was extremely expensive.
- lisper 7y ago
  This is a much more profound insight than is readily apparent. It is really easy to build a Turing machine -- except for the tape. You could probably build a universal TM is a lot less than 930 gates. All hardware design is essentially nothing more than taking common design patterns and moving off the tape and into the engine so that the tape can be more compact and the machine can run faster. This is the main reason I personally find actual hardware re-implementations of old machines to be fairly uninteresting. There's really very little sport in it once you know the trick.
  - jacquesm 7y ago
    74 series gate golf to get the most compact hardware brainfuck implementation: http://grapsus.net/74/ http://grapsus.net/74/
    - lisper 7y ago
      I have to admit that is pretty cool in a sick and twisted kind of way.
- ttldude 6y ago
  It doesn't need a large memory if remove the video, or if you change it to B/W.

tyingq 7y ago

There were commercial computers that did. The PDP-8, as one example (not 74xx, but similar). Edit: The Xerox Alto CPU was built with 74181 chips. Cost, power consumption, space, etc, are all disadvantages. I assume the Gigatron is using modern 74HCxx CMOS chips, which consume less power than the original 74xx TTL chips.

dboreham 7y ago
Yes HC didn't exist and 4000 CMOS was slow. Plus the pcb, assembly and test cost for 40 DIP packages is significant.
ttldude 6y ago
Typical discrete logics designs were much larger than the Gigatron. So they're not the same. Using 74LS the single board draws 2.5 W.

klodolph 7y ago

The short answer is that computers with CPUs made from 7400 series TTL existed, but they weren't "micro".

tyingq 7y ago
The Kenbak-1 might be considered an exception to the rule: http://www.kenbak-1.net/index.htm http://www.kenbak-1.net/index.htm

djmips 7y ago

930 logic gates + 1K of microcode ROM (so how many gate equivalent is 1K of ROM?) and it only runs 1/4 speed of a 6502.

xkriva11 7y ago

The simplicity of Gigatron is compensated by the large memory that was extremely expensive.

lisper 7y ago
This is a much more profound insight than is readily apparent. It is really easy to build a Turing machine -- except for the tape. You could probably build a universal TM is a lot less than 930 gates. All hardware design is essentially nothing more than taking common design patterns and moving off the tape and into the engine so that the tape can be more compact and the machine can run faster. This is the main reason I personally find actual hardware re-implementations of old machines to be fairly uninteresting. There's really very little sport in it once you know the trick.
- jacquesm 7y ago
  74 series gate golf to get the most compact hardware brainfuck implementation: http://grapsus.net/74/ http://grapsus.net/74/
  - lisper 7y ago
    I have to admit that is pretty cool in a sick and twisted kind of way.
ttldude 6y ago
It doesn't need a large memory if remove the video, or if you change it to B/W.