8088 vs. 80c88

[Chuck Guzis]

On 26 Feb 2009 at 7:38, Les Hildenbrandt wrote:

> I am sorry I am so slow here.  Which is the problem?  The value or the sequence?

ISTR it was SP == call target address that precipitated the problem.  
Darn it, are you going to make me go digging through over 20 years of 
notes to find the thing?

> The Z80 thing is an interesting point.  Before I started running CP/M
> on a V20, I allways ran on a 8085.  I would get annoyed when cp/m
> software required a z80, because it was not a z80 operating system.  I
> later did build a few z80 systems, a laptop and a 20mhz sbc system,
> but all of the coding I did for them was 8080, except for using the 16
> bit io address features of the z80. 

ZCPR and some compression (ZIP-type) utilities are the ones that made 
me wish I had a Z80 in my system and not an 8085.  I've got some 
NSC800 CPUs--I figure that I might be able to shoehorn one into an 
8085 system with a little glue (as long as the system doesn't use RIM 
and SIM).  Or maybe not, but it's close.

> I assumed the rabbit was a z180, you learn something new every day.  I
> have done a few designes with z180's, but I cant even rememer what
> language tools I used at this point. 

The Rabbit Semiconductor R2000, R3000, R4000 series (still being 
made) are Z80/Z180 "sort-of".  Lots of "rarely used" opcodes (e.g. 
DAA, IN, OUT, etc.) are replaced by other instructions.  See:

http://www.rabbit.com/documentation/docs/manuals/Rabbit4000/Instructio
nReference/

How much patching do you think it would take to get CP/M to run on an 
R3000?

--Chuck