Homebuilt TTL and transistor CPUs - wierd logic

[Jim Battle]

Chuck Guzis wrote:
> On 1/25/2006 at 12:50 AM ard at p850ug1.demon.co.uk wrote:
> 
>>> Balanced trinary means place values go up by three each, but instead 
>> Personally, I prefer negabinary (base -2). It uses 2-state signals, but 
>> the column values are powers of -2 : . . .16, -8, 4, -2, 1
> 
> Didn't the 8087 use ternary (base 3) for some of its internal logic?
> 
> --Chuck

No, my memory was that it used 4-state cells to encode two bits per cell 
in the microcode rom.  Rather than transistor/no transistor to represent 
0/1, it used no transitor = 00, weak transistor=01, normal 
transistor=10, strong transistor=11, or something akin to that.

That sounds great, except that the bit cells were a substantial portion 
of twice as big as a simple one bit/cell design.  There was some area 
savings, but not 50%.