Jos Dreesen wrote:
>
> Tony Duell wrote:
> >
> > >
> > > 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.
> >
>
> 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
Well NIXIE tubes make nice I/O for a 12 bit computer.
--
Ben Franchuk - Dawn * 12/24 bit cpu *
www.jetnet.ab.ca/users/bfranchuk/index.html
Received on Wed Apr 10 2002 - 15:55:46 BST