[ih] Intel 4004 vs the IMP

[Clem Cole]

On Mon, Nov 15, 2021 at 9:19 AM Steve Crocker via Internet-history <
internet-history at elists.isoc.org> wrote:

> Might it be possible to pin down the crossover date?  That is, when did a
> microprocessor appear that was of the same power as the Honeywell 316?
>
> Well gioce these are the features of the 216:

The programmers' model of the H-316 consisted of the following registers:


   - The 16-bit *A* register was the primary arithmetic and logic
      accumulator.
      - The 16-bit *B* register was used for double-length arithmetic
      operations.
      - The 16-bit *program counter* holds the address of the next
      instruction.
      - A *carry flag* indicated arithmetic overflow.
      - A 16-bit *X index* register was also provided for modification of
      the address of operands.

The instruction set <https://en.wikipedia.org/wiki/Instruction_set> had 72
arithmetic, logic, I/O and flow-control instructions.

What I don't remember is the clock frequency, but I think it was in the
order of .5-1Mz.  It used core which teneded to be slower than
semiconductor memory at the time.

So, I suspect if you just match the ISA's, first commercial microprocessor
to come close to that would have been the M6809 which was introduced in
1978, which had two 8-bit A/B accumulators which combined to single 16-bit
accumulator but also has a 16-bit D accumulator.  It also had 2 16 bit
index registers (X and Y).   It was usually combined with semiconductor
memory and clocked at 2 Mhz.

The M68000 would come out as an experimental (unnumberred) chip for a 10 of
us a few months later and would be released for GA, in early/mid '79 [I was
one of the people with the X-series chip at Tektronix, so I really don't
remember the final GA time).  Certainly it would been workable.

The question is if an 8-bit processor with a 16-bit address space like the
8080/Z80 or 6800/6502 would have been good enough.  They all tended to use
semiconductor memory, so the memory speed of the 316 is likely to have been
able to be matched/exceeded.  But the question is open if the code when
converted to 8-bit ops to perform what had been done in 16-bits would have
been reasonable.

My >>WAG<< is that since so many slick video games got built on the 1Mhz
6502, I think an IMP might have been possible but  would have taken some
very slick and careful coding I suspect.

ᐧ