8088 vs. 80c88

[Les Hildenbrandt]

>
>
>> I am assuming the problem relates to following a lxi sp instruction
>> immediatly with a call instruction, I can see how pipelining
>> instructions could cause this failure.   I cant immagine how calling
>> the address which happens to match the sp would be an issue. 
>  
>

>As far as we could determine, it was precisely the issue. 

>> My thought was that most cp/m programs either left the sp alone, and used
>> the stack provided by cp/m, or set up a local stack early on in the
>> program.  In either case this bug could be completly avoided.  Am I wrong
>> here?  Is the bug related to calling the address which happens to be in
>> the sp?
>  
>

>Again, yes.

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

>Probably not a bug, but definitely a factor in determining if I 
>should have bothered to use the V20/30 for emulation at all.  
>Certainly, I wondered if the lack of Z80 instruction set support 
>would have been an issue.  It was--and I supplied a software emulator 
>for that.  Fortunately, I also included an software 8080 emulator, so 
>even users of JRT Pascal weren't left hanging.

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.

>To clarify my point, would you try to run CP/M on a Rabbit uC with 
>all of its "we're just like a Z80 except when we're not" instruction 
>set?  I've never tried, as the compatibility issues are just too 
>severe.

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.

Les


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