Re: A bit more on bits...

[Sean Conner <sean@...>]

It was thus said that the Great Peter Hickman once stated:
> On Thu, 16 Feb 2023 at 21:56, Sean Conner <sean@conman.org> wrote:
> 
> >   Um, aside from using AX (which is from the 8086),
> 
> The Z80 was software compatible with the Intel 8080. 

  Note that I wrote "eight-zero-eight-SIX", not "eight-zero-eight-zero". The
8080 also did not have an AX register.  The 8080 and Z80 both have an A
register; the 8086 equivilent of this is AL (the lower 8 bits of AX).

> The only "difference"
> was that the assembler used different names for the instructions and
> registers. This was the only thing that Intel could have called copyright
> on. There was no copyright protection on the silicon itself unless Zilog
> copied the chip design verbatim. The first true "clean room" clone :)

  And Zilog added a few registers and instructions over the 8080.  And then
the 8086 comes along, and while it's neither binary compatiable nor software
compatible, one could mechanically translate 8080/Z80 code to the
8086---this was how much of the early software for the 8086 was done.

> Thank you for coming to my Ted talk :P

  You're welcome.

  -spc ("I'll pick 'Pedantic details about 70s microprocessors for $600,
	Ken.")