4 Apr
2007
4 Apr
'07
6:11 p.m.
Billy responds:
That was pretty much the modus operandi on early MSI/LSI chips. All of the
early ASIC's I worked with were bread boarded from SSI or even single gate
ICs. The vendors would provide design kits with lots of these little chips.
Most of them were 4 or 8 pins; a few were 14 or 16 pins. You can still buy
them today to patch bugs on LSI until you can roll the metal. First ones
were TTL, then they moved to CMOS. I even remember one ASIC that we used
ECL gates on.
I still have ca. 4000 TO-5 cans that contain two bipolar transistors
each, nothing else . These were intended for IC prototyping.
Now what was the 8080`s transistor count again ?...
Today patching IC's is done with the spare gates that are distributed
along the regular logic.
wrt to homebuilding TTL based cpu's : the fun part is the design. The
actual building takes a lot of dedication. I would advice against
building a 32 bit cpu as a first project.
Jos