FPGA VAX update, now DIY TTL computers

[woodelf]

Stegeman, Henk HJ SITI-ITIBHW5 wrote:

>Hi Jos, 
> 
>I fully agree with you. Building your own CPU is really an exciting project. 
>I took me more then 3 months to debug my 110 TTL CPU with 
>256 words of micro code of 48 bits.   
> 
>  
>
I have been trying since I was about 12. Now I am a old GEEK and still 
trying to save
my pennies up parts. I can never get a clean TTL design under about 300 
chips for the
data path and 150 for the control unit.

>See: http://www.anysystems.nl/hjs22.html  for some pictures and the 
>reference card.
>  
>
This is a nice CPU.

>  
>
>>What surprises me about the home-built computers from scratch is the 
>>lack
>>of imagination when it comes to architecture.  Most are basically
>>one-address-cum-accumulator designs.  It would seem that larger 
>>register
>>files are much easier to build nowadays and would open up the door to 
>>some
>>2 and 3-address designs. 
>>    
>>
I would bit slice would be better for that route, it is lot of 
instruction types
that add up with multi-address opcodes.

> 
>In 1974 Elektor magazine started a series of DIY articles that described
>an extensible ( 12 bit or 16 bit width ) three address, clockless 
>computer.
>TTL based, with a shiftregister based memory.  (6 or 8 512x2 
>shiftregisters .)
>  
>
Living in Canada I was Computer deprived .... I'll read the DIY stuff 
now and maybie build it
in 20 years :)