Altair Emulator enhancements - progress report - questions

From: Cini, Richard <RCini_at_congressfinancial.com>
Date: Tue Sep 12 12:01:40 2000

>>Dwight wrote
>There was no standard port used for serial I/O. and even if
>there was, the device could have been a AY-3-1015, a 8251 or
>a 8250. All of these would have different handshake and
>setup information. I don't know how you'd be able to have
>anything that you'd call standard.
>Dwight

I guess that my question was partially answered by Jim. Using Altair BASIC,
BASIC polled the switches (at port FF) in order to determine which ports to
use for various I/O. Disk BASIC was the choice (running over CP/M), the BIOS
would have to be recompiled with the proper port locations for the hardware
one was using.

What I was kind of getting at was as follows. If I wanted to provide
emulated console I/O, what port would I virtualize so that any software I
loaded would run? I guess that my PeeCee-centricity was showing a bit in
that in the PeeCee certain hardware ports were always at the same location.

So, the conclusion is that if I want to emulate a single console port, I
have to select which serial board to emulate (the 2-SIO for example) and
virtualize ports 20Q and 21Q.

It also sounds like that I need to trap input port 0xff as the "sense
switch" port. This may be done in the emulator already; I have to check.


Rich

-----Original Message-----
From: Dwight Elvey [mailto:elvey_at_hal.com]
Sent: Tuesday, September 12, 2000 12:35 PM
To: classiccmp_at_classiccmp.org
Subject: Re: Altair Emulator enhancements - progress report - questions


"Cini, Richard" <RCini_at_congressfinancial.com> wrote:
>
> I also have some questions of actual users of the Altair. I wanted
> to use a copy of Palo Alto Tiny BASIC on the emulator (because that's the
> BASIC that I have), but TB relies on CP/M for console I/O. Regarding the
> original Altair BASIC, did the BASIC code provide its own I/O services or
> did it use CP/M also? What port locations were generally used to service
> serial ports used for console I/O? Does anyone have a working set of CP/M
> binaries that I can load into the emulator?

Hi
 There was no standard port used for serial I/O. and even if
there was, the device could have been a AY-3-1015, a 8251 or
a 8250. All of these would have different handshake and
setup information. I don't know how you'd be able to have
anything that you'd call standard.
Dwight
Received on Tue Sep 12 2000 - 12:01:40 BST