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Re: [OT] DOS history, was: [OM] Unknown Wide Zoom Oly Mount

Subject: Re: [OT] DOS history, was: [OM] Unknown Wide Zoom Oly Mount
From: davidt@xxxxxxxxxxxxx (David Thatcher)
Date: Tue, 6 Mar 2001 15:17:14 +1030 (CST)
Tim wrote:
> The CPM API was mainly done through software 
> interupts with register variables setup to do whatever function you wanted. 
> Paterson duplicated the API functions added some of his own and mimicked the 
> described behaviour. He wanted programmers to be able to port their software 
> very easily from CPM. 
 

it was duplicated to the level that the first 100 (hex) bytes ( all
programs under cp/m started execution at 0100H) contained the
appropriate cp/m  BDOS subroutine call at location 0005H  in addition
to the recommended DOS software interrupt, & most of the 'BDOS primate
functions', (print character, get key input, print string, etc.) carry
the same 'a' register 'selector' values.

DavidT
Adelaide 

South Australia



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