Serial Configurations (was Devilish Altair Serial ConfigurationProblem)

Richard A. Cini rcini at
Sun Jul 31 21:06:51 CDT 2005


	No success so far. I'm going to write a small test program
tomorrow to accept a character from the SSM and echo it back. I have the
two ports configured two different ways -- the first equivalent to a
Revision 1 SIO (active low) and the second equivalent to an 8251. It's
still a remote possibility that the board is bad, so I hope this will
flush it out.

	I'm still hopeful that someone on the list has a working SSM
2p-2s that they could report on how it's configured and how the cable is
wired. This has bothered me all day, which usually means it's a hardware


-----Original Message-----
From: cctalk-bounces at
[mailto:cctalk-bounces at] On Behalf Of Allison
Sent: Sunday, July 31, 2005 3:09 PM
To: cctalk at
Subject: Re: Serial Configurations (was Devilish Altair Serial

>Subject: Serial Configurations (was Devilish Altair Serial
>   From: "Richard A. Cini" <rcini at>
>   Date: Sun, 31 Jul 2005 12:35:05 -0400
>     To: "'General Discussion: On-Topic and Off-Topic Posts'"
<cctalk at>
>	The problems I'm having have to be related to status bits and
>initialization. The board is an SSM 2p+2s which is based on the TMS6011

>(which has lots of equivalent UARTs such as the COM2502, 2017, TR1402, 
>AY3-1015). The SSM board is very flexible -- I can change status bit 
>order and polarity to match almost any configuration need. Right now I 
>have it strapped to match the Altair Revision 1 SIO board (ports 0/1, 
>RxStat=bit0, TxStat=bit1, active high polarity). I've also tried TxStat

>at bit7.

That should work.

>	Does someone have sample working code for initialization, input
>output? I have a few datasheets but none of them give sample code 
>sequences. I'm missing something here and I'd appreciate a push.

OH, one more detail.. Most of the MITS software when loaded inits 
based on the front pannel sense switches (IN FFh).  The configuration
sets the board in use and bits.  T he setting are in the MITS software


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