31 Jul
2005
31 Jul
'05
3:55 a.m.
Subject: Devilish Altair Serial Configuration Problem
From: "Richard A. Cini" <rcini at optonline.net>
Date: Sat, 30 Jul 2005 22:40:19 -0400
To: "'CCTalk'" <cctalk at classiccmp.org>
All:
This problem has been beating me up all day so I wanted to throw
it out to the group for ideas.
In my 8800b, I have a Vector Graphics Bit Streamer serial board
(8251 chip) set for standard ports (0/1 parallel, 2 serial data, 3
serial command/status). I modified the Turnkey Monitor to use the ports
based on the VG instruction manual. The manual outlines initialization
and moving characters in and out. Works perfectly.
the base altair boards were com2502 based on the RXrdy and TXempty bits
sis not corrospond with 8251.
Now, I want to get standard Microsoft BASIC paper
tapes (8k or
Extended 4.0) working with this board. However, when I look at the sense
switch options, none fit using the Bit Streamer -- the parallel ports
are swapped with the serial ports in the order, and the data port comes
before the status port (all basically the opposite of what BASIC
expects). I also can't seem to find a toggle loader that works properly.
Will not work. The MITS loader was specific to the mits boards unless
you modified them. However then the loaded image (BASIC) will still
need the drivers patched. The expected boards were either MITS SIO
or the 2SIO.
So, I decided to pull out a Solid State Music 2p/2s
board and
try to configure it to work with BASIC. I spent the better part of a day
trying different options with no success. Based on some basic testing of
the board I believe it works.
The board may be ok but it will not solve the basic problem of
correct IO address and bits within BASIC.
Has anyone configured an SSM board to successfully
work with
Microsoft Tape BASIC? What loader did you use? How about getting a
standard VG Bit Streamer working with standard MS Basic?
Neither, never had them.
Back when faced with the MITs IO and some of the problems of
storage I took a different route until I got a disk.
I used a MITS SIO-B for the console (address 0/1). The
original load was done using a MITS ACR from audio tape for
the 8K and the extended 12k. Then the system was stopped
and a hand loaded program saved the image to a different
tape system as a binary save. The goal being to get away
from MITS ACR (unreliable on a good day) or PTape
(SLOW!!!).
The audio tape system was homebrew and ran NRZI at 4800 and
later 9600 using a Redactron digital casette tape deck (saturation
recording, not audio). The inital load file was straight
binary with a loader that looked for a leader byte and then
stuffed memory till byte count equaled zero. Later versions
evloved to CPU control of the tape drive and blocked files.
As an aside, I'm using Procomm from DOS on an old
PC. Can one
use the "ASCII Upload" option to move the tape image over the line or
should I do something from DOS like "copy 8kbas40.tap com1:"?
Using todays tech (a PC) I'd render the BASIC to a binary image
on the PC (using a sim if needed) and download it using straight
binary transfer (8n1 terminal) to a simple binary loader. At
9600 baud it's plenty fast and low error. Also using a SIM
you can get inside the BASIC and find all the IO instructions and
change the relevent routines. I had to do that using the
ALTAIR8800 front pannel.
I stopped using all that when I started using NS* MDS with NS*dos
and NS*BASIC back in late 1977.
Allison