Date : Sat, 23 Apr 1988 19:23:05 GMT
From : portal!cup.portal.com!dick_a_wotiz@uunet.uu.net
Subject: Fail to install P2DOS on Apple
> I promised Don Kirkpatrick a full report of what I did. Here it comes:
> - my configuration is an Apple ][+ with 64 K of RAM, for running CP/M
> I have a Softcard 60K with a Z80 processor.
> .
> .
> addresses in image file addresses in high memory
> ======================= =======================
> CCP: F00h - 17FFh CCP: D300h
> BDOS: 1800h - 26FFh BDOS: DC00h
> BIOS: 2700h - 2CFFh BIOS: FA03h
>
> P.S.: This are the addresses which I think the CCP, BDOS and BIOS
> probably begin ? If NOT correct please let me know, because
> the whole installation procedure falls or stands with it !
A while back I disassembled and analyzed CPM60.COM for CP/M 2.23 on my
Apple II, and this is the memory map that it appears to use:
CPM60.COM address memory address
----------------- --------------
BIOS 500h - AFFh B000h - B5FFh (in Language Card Bank #2)
CCP F00h - 17FFh D300h - DBFFh
BDOS 1800h - 1BFFh DC00h - DFFFh
BDOS 1C00h - 26FFh B5C0h - BFBFh (in Language Card Bank #2)
BIOS 2700h - 2CFFh FA00h - FFFFh
Since the Apple only has contiguous memory from 0000h - DFFFh, it is
necessary to split the BDOS into two parts; one is in high memory at
DC00-DFFFh, where you would expect it to be, but the other half is
in bank-switched memory, accessible only if the appropriate bank-switching
routines are inserted into the DC00-DFFFh section of the BDOS.
Likewise, the BIOS is split in two pieces in memory.
I don't think there is any easy way of installing a different BDOS
without very extensive modification/customization for the memory
configuration that Apple uses.
By the way, someone reminded me that this 'warped' implementation of
CP/M is not Apple's fault, as I had implied in a previous posting.
It was developed for them by Microsoft for the Softcard.
(Hmmm.... aren't they one of Digital Research's competitors, anyway? :-) )
Dick Wotiz dick@portal.com
dick@cup.portal.com
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