CP/M survey

[Allison]

>
>Subject: Re: CP/M survey
>   From: "Chuck Guzis" <cclist at sydex.com>
>   Date: Thu, 19 Apr 2007 09:25:46 -0700
>     To: "General Discussion: On-Topic and Off-Topic Posts" <cctalk at classiccmp.org>
>
>On 19 Apr 2007 at 9:48, Allison wrote:
>
>> >Maybe, but it couldn't run JRT Pascal.  AFAIK, the only commercial 
>> >product that ever used the bizarre coding sequence:
>> >
>> >    LXI	SP, PROC-1
>> >    CALL	PROC
>> 
>> JRT Pascal was Z80 code if memory serves.  But LXI SP, value is
>> valid as the arithmetic is done at compile time not execution. 
>
>Nope--8080.  I've still got the 1.0 disk.  One can precede this 
>sequence with (and I think that JRT did):

I have V3 and never had a problem, guess they fixed it.

>
>    LXI H,0
>    DAD SP

Only way to get the SP on 8080.  Liked the Z80 because they fixed that.

>to get the old SP value into the HL register pair prior to the LXI 
>SP.   And it is a V20 bug--I remember calling the NEC technical guy 
>in Natick and getting about 10 words into the report and having him 
>say "JRT Pascal, right?".  If anyone's interested in the V20 errata, 
>I've still got the stuff.

Was that Charlie or Ted?  I'd like to see the report or erata mostly 
since it would fit nicely in my NEC file.

>JRT was one of the earlier attempts at "virtual" 8080 code; it 
>swapped procedures from floppy.  Of course, it was miserably slow, 
>but at something like $30 for a Pascal, it looked like a great deal.  
>Of course it was buggy as the dickens.  I think the oddball calling 
>sequence was to keep the stack adjacent to the procedure for 
>subsequent swapping, rather than having to deal with a single stack 
>that might well overflow without special handling routines, given the 
>"virtual" nature of JRT Pascal.

Doing anything on 8080 that was virtual was slow.  V3 was still $30
and slow but it did work.

>> In the end running an 8080 (V20) 
>> when I have Z80 or even fast(6mhz HmosII) 8085s is sort of 
>> less than interesting.
>
>Maybe, but you use what you have at your disposal, even if it is an 
>8080.  And most professional apps for CP/M used the 8080 instruction 
>set initially--only later did a bunch of Z80-specific (e.g. ZCPR) 
>code come out.  I never could understand this--in general, little to 
>be gained in speed by using Z80 codes.

By time the V20 hit the street I was running hand upd780s at 8mhz
and had at least three s100 crates going.

>FWIW, I still use 22NICE on Win2K.  It nicely integrates old CP/M 
>apps into the Windows environment without having to create virtual 
>disks or such stuff, so using apps under emulation is no harder than 
>using native ones.

Still have it and use it, interesting tool.


Allison