"CP/M compatible" vs. "MS-DOS Compatible" machines? - test-drb@ccmp.vtda.org

1 Feb 2008

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Subject: Re: "CP/M compatible" vs. "MS-DOS Compatible" machines?
   From: Roger Ivie <rivie at ridgenet.net>
   Date: Fri, 01 Feb 2008 08:05:02 -0800 (PST)
     To: "General Discussion: On-Topic Posts Only" <cctech at
classiccmp.org>

On Fri, 1 Feb 2008, Allison wrote:

 Done right it was portable.  However I encounterd at least one system
 where the BIOS calls were unusuable for 8bit serial because every
 transaction in or out was masked with 07Fh.. 
Which is consistent with the manual:

"All simple character I/O operations are assumed to be performed in
ASCII, upper- and lower-case, with high-order (parity bit) set to zero."

(from the section 6 of the CP/M 2.2 manual) 
It is sorta..  Parity may not be a visible bit if the terminal is 
set for 8P1, the manual would imply the required serial format is
7S1 or 7S2 which may be for TTY but not always.

The manual is at best obscure on that.  ;)

My implmentations had two serial drivers TTY (masked to 7bit)
and CRT not masked. Add to that printer (DEC LA100) serial 8bit
and modem 8bit I used the high and low bits of IObyte usefully.

Allison

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roger ivie
rivie at ridgenet.net 