RS-232 Problem (Configuration ?)

From: Mike Davis <ipscone_at_msdsite.com>
Date: Mon Feb 17 23:54:01 2003

Tada! Man that was frustrating. But I found the problem. Turns out
that I had another board in the system that was conflicting with my
SIO.

I was reading the IMSAI manual for the SIO (which is far too short)
and after that there was a section on the MIO. I began to think that
maybe the MIO was used instead of the SIO. Nope! That wasn't the
problem. But just on a hunch, since I hadn't checked the addressing,
I removed the MIO board. Tada! It all began to work.

Evidently, the MIO was added later and never tested with the drive.
I'll leave that for the weekend but at least I have my North Star
drives booting and working properly now.

Whew! Thanks to those that tried to help.

Mike

> >From: "Mike Davis" <ipscone_at_msdsite.com>
> >
> >Let me start off by saying "I hate RS-232". Anyway, now that that's
> >out of the way, I am having a problem with an RS-232 interface on an
> >IMSAI SIO board.
> >
> >I've been debugging a North Star drive and I was having problems with
> > it booting (DOS 2) in my IMSAI. I would get the "*" prompt but OS
> >would not recognize my Soroc terminal input. At first I thought it
> >might be buggy code on my DOS floppy.
> >
> >Anyway, to make a long story short, I have multiple of everything and
> > have ruled out everything but something to do with my RS-232
> >configuration (I guess). I have 2 SIO board and both behave the same
> > way.
> >
> >I'm documenting what I have here, in case someone sees something
> >wrong that I've overlooked. BTW, this was previously working without
> > any different configuration or hardware, with the exception of the
> >RS- 232 cable from the Soroc to the IMSAI. This is a brand new cable
> > that was working just a few weeks ago so I'm having a hard time
> >believing there is anything wrong with this cable. I have only one,
> >if you can believe that. I'm going to get another this weekend, if I
> > have not figured this problem out by then.
> >
> >Anyway...
> >
> >I'm using Port A (on the SIO) and have configured the A3 Jumper to
> >have
> >
> >TD Pin 1 to Pin 15 RD
> >RD Pin 2 to Pin 16 TD
> >RTS Pin 4 to Pin 12 CTS
> >CTS Pin 5 to Pin 13 RTS
> >DTR Pin 7 to Pin 9 DSR
> >DSR Pin 8 to Pin 10 DTR
> >
> >By the way, the SIO manual shows DTR-DSR as through straight throuh
> >in stead of crossover, as shown above. Seems that it should be
> >crossed over like the others. In any case, I have tried both ways
> >but it doesn't seem to make any difference.
> >
> >I'm using a straight through DB-25 cable from my Soroc to my IMSAI.
> >
> >I'm using the following CIN and COUT routines.
> >
> >2900 DB03 CIN IN STAT
> >2902 E602 ANI IBIT
> >2904 CA0029 JZ CIN
> >2907 DB02 IN DATA
> >2909 E67F ANI 7FH
> >290B C9 RET
> >
> >290C DB03 COUT IN STAT
> >290E E601 ANI OBIT
> >2910 CA0C29 JZ COUT
> >2913 78 MOV A,B
> >2914 D302 OUT DATA
> >2915 C9 RET
> >
> >Areas I'm wondering about.
> >
> >1) Is the A3 header correct for the IMSAI as the computer end and the
> > Soroc as the terminal. 3 pairs crossed over. It does write to the
> >Terminal properly and when I press the Break Key, I get an echo from
> >the IMSAI of *?, which seems normal.
> >
> >I have tested the input routine, which is part of the DOS input
> >routines, and was working previously, by modifying it to display the
> >status to the programmed output on the IMSAI with this code.
> >
> >0000 DB03 CIN IN STAT
> >0002 DBFF OUT FFH (programmed output port)
> >0004 E602 ANI IBIT
> >0006 CA0000 JZ CIN
> >0009 DB02 IN DATA
> >290B E67F ANI 7FH
> >290D C30000 JMP CIN
>
>
> Hi
> There may already be a status in the port, that maybe
> why you see no change. You need to put a dummy read first.
> This will cause the drop of alternate characters when
> working right but this is for debug. Try:
>
>
> CIN IN DATA
> CIN1 IN STAT
> OUT FFH
> ANI IBIT
> JZ CIN1
> IN DATA
> ANI 7FH
> JMP CIN
>
> If you don't see any change, try some of the other ports,
> near by for STAT, like 0 , 1 or 2.
> If that fails, you could be having a problem with the
> serial lines someplace. You need to check the levels
> on the serial chip inputs.
> Dwight
>
> >
> >Seems that this should show whatever is read in the status port for
> >Port A. But when executed, the status never changes after I tap any
> >key.
> >
> >My system is behaving as if it just can't receive any data from the
> >terminal. It's driving me buggy as this is a relatively simple
> >problem. Like I said, I have multiple SIO and they all behave the
> >same. I even tried another terminal and get the same results. I
> >have also even tried different ribbon cable from the SIO to the RS-
> >232 connector.
> >
> >Anyone see something bonehead that I overlooked?
> >
> >Thanks,
Received on Mon Feb 17 2003 - 23:54:01 GMT

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