Physical Implementation of Hack Computer without FPGA

[rmarion]

Hello forum!

I'm a high school student, and was wondering if it was possible to make a physical implementation of the HACK computer without the use of a FPGA. This would mean creating the computer with integrated circuits like adders, registers, multiplexors, etc. I've done some research on my own, and it seem's like it would be possible, however I am very unsure as to how the machine would connect to a monitor, and if it could even be implemented at all.

Any response would be greatly appreciated.

[cadet1620]

rmarion wrote

I'm a high school student, and was wondering if it was possible to make a physical implementation of the HACK computer without the use of a FPGA. This would mean creating the computer with integrated circuits like adders, registers, multiplexors, etc. I've done some research on my own, and it seem's like it would be possible, however I am very unsure as to how the machine would connect to a monitor, and if it could even be implemented at all.

It should be possible to make a Hack-like computer using TTL or CMOS ICs. I say Hack-like because the Screen display is going to be problematic. The easiest thing to do would be to replace the Screen and Keyboard with a UART and use a serial terminal or serial port on a PC.

Memory will need to be slightly different too. RAM chips I'm familiar with have separate read and write cycles so you will need to implement a double rate clock so that the RAM reads during the first half of the Hack clock cycle and, if required, writes during the second half.

I've implemented (simulated) the Hack CPU and ALU in Logisim with 7400 series TTL and ended up with the following chip count:

   CPU           ALU
----------    ----------
74LS00   2    74LS02   1
'LS08    2    'LS08    4
'LS10    1    'LS30    2
'LS74    1    'LS83    4
'LS157   8    'LS86   12
'LS163   4    'LS157  12
'LS273   4    'LS240   2

If you would like my TTL library for Logisim, email me.

--Mark

[edv56]

If you are interested in a very physical implementation you could try making a drum memory based computer:
https://www.youtube.com/watch?v=4vz5JZCNBCg

I still have quite a ways to go to even get to a a simple state machine.

[tungsten]

This post is old, but sharing for anyone curious.

Here is a great playlist I've recently come across that walks you through physically building a computer (without using an FPGA). It is directly applicable to Hack.

https://www.youtube.com/playlist?list=PLowKtXNTBypGqImE405J2565dvjafglHU

It goes through everything including the clock, d flip flop, adders, alu, memory etc.

Figuring out the screen and keyboard interface is another problem, but one that is also solvable. Once you get the computer working, you can checkout sites like Adafruit and Sparkfun for maker/diy friendly IO devices you can add to it.