semi-homemade micro

[Jim Battle]

Brad Parker wrote:

> Jim Battle wrote:
> 
>>The original PDP-8 took 10 clocks at 1 MHz to execute one instruction
> 
> 
> really?
> 
> I'm probably off, but at a cocktail party I would would have said that
> some instructions took 8 clocks (f0,f1,f2,f3,e0,e1,e2,e3) and some took
> 12 (f0-f3, d0-d3, e0-d3).
> 
> That's according to a recent look at the "blue book", but I may have
> misunderstood.  I did write up some verilog which uses those states and
> it seems to be (mostly) correct, but it's done all debugged yet.
> 
> -brad
> 
> 

I'm no PDP-8 expert.  My source was this web page:

http://fixedreference.org/en/20040424/wikipedia/PDP-8

"The PDP-8 was a 12-bit computer with 4096 words of memory. It had only eight 
instructions, one full register, the accumulator (AC), and a single-bit 
register, the link (L) bit. The machine operated at a clock rate of 1 MHz, and 
took  10 clocks for each instruction, so that it ran at 0.1MIPS."