10 Apr
2002
10 Apr
'02
2:01 p.m.
Tony Duell wrote:
If it's really SSI then it really is a low count.
Around '86 I build a 12 bit TTL based computer : 3 x 74ls181 as an alu, hardware
stack build around 3 2111 SRAM's and 8K main memory ( 2x6264's)
Total count : 85 TTL IC's ( MSI and SSI) and 5 SRAM's. It fitted neatly on 3
eurocards.
It used no microprogramming and no PROM's.
Building the same thing in SSI would have easily cost 6 times as much IC's.
It was, however, a bit lacking in I/O : it had 4 nixie tubes, but no serial or
parallel IO......
Jos Dreesen
Playing aroud a bit with TTL using SSI parts, I get about 8-10 chips per
bit on the average for the alu. For 16 bit computer that is about 160
chips. I would say 1/3 more for control or about 250 chips total. Does
this sound right people with 16 bit TTL computers?
IF by 'SSI' you mean just simple gates and flipflips ('74, '76, etc)
then
it sounds far too few.