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Using IBM Async card with teletype

billdeg

billdeg

Technician
Joined
Nov 18, 2003
Messages
3,885
Location
Landenberg, PA USA
Hi all...I have wired up a connector (pins 9,11,18,25) from an IBM async card installed in an IBM XT which I attached to my teletype terminal strip on the other end. The teletype works fine with other computers, but I tried three nice-shape async cards, the teletype never stopped chattering (ready mode). I need to check the async cards more closely, but I am going with the assumption for now that at least one card works.

I flipped the jumper chip on async card's U5 per the manual.

According to my notes
http://vintagecomputer.net/browse_thread_record.cfm?id=422&tid=1
You're also supposed to flip a jumper on J13...where is J13?

Anyone got an IBM PC attached to a teletype (now or in the past)....I would appreciate some tips/ideas. I will proceed with voltage testing of each pin looking for clues.

Bill
 
100ma = current. Note that some DMMs require that you move a probe to a different receptacle to measure current--it's for your own protection. When you measure voltage, be sure to move the probe back--trying to measure voltage with the probes set for curent can lead to grief. The circuit path between pins 9 and 11 has a resistance to limit current. (CL interface is designed to tolerate short-circuits)
 
It would kinda sorta help if I had the wires on the right pins...duh. Got it running, thanks. I am setting up a quick way to back up papertapes using a PC.
 
Yup. I have three boxes of papertapes from the Altair/IMSAI era to archive. Hopefully I can find a terminal program that runs on the IBM PC and can do 110 baud. Despite the slow 110 baud, once the files are on the IBM PC its easier to copy to the Internet. I will post on my site once I figure out how to do it.
 
billdeg said:
Yup. I have three boxes of papertapes from the Altair/IMSAI era to archive. Hopefully I can find a terminal program that runs on the IBM PC and can do 110 baud. Despite the slow 110 baud, once the files are on the IBM PC its easier to copy to the Internet. I will post on my site once I figure out how to do it.
Click to expand...

I was not able to find a teletype-compatible terminal program, anyone have one? (works on a 8088, compatible with a IBM async card or others of the ISA era)...if I find one I will update this post).
 
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Of all of the various terminal programs that I have at home and will run on the 5160, none provide 110b option, they all assume a modem. Didn't IBM put out an early terminal program that had 110b support? Bare in mind that IBM put current loop support into the IBM async card to make it possible for the IBM PC to hook up to legacy IBM printers that used a current loop more so than to allow the IBM PC to connect to a teletype.

I wonder if there was anything that came with DOS 1.1 or 2.0. I also have an IBM Financial Input Adapter which may touch upon teletypes and the IBM PC, not sure.
http://vintagecomputer.net/vcf8/Degnan_exhibit_IBM-option-boxes.jpg

Kermit for DOS or Telix,etc. THe question is - do they have a 110b setting? Any version of Kermit I had was bundled with a comm program. I have not checked Telix, but it's a later 80's package, long after anyone used an IBM PC with a teletype.

So, I am thinking that I should research the HAM radio angle, and Greenkeys, etc. for solutions. I don't expect many commercial software packages to include current loop support, when most async cards did not have the IBM easy switch feature. It makes most sense to seek an IBM branded solution.

So - what IBM-branded comm's software or programs were published in 1981-82? Off to the bat cave...
 
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Quick update - I found the Asynch Communications Support manual and software, which I think is what I need. I really just want to use the teletype as a console, I believe an OS level or even BASIC program should work to do what I want. After work today I will set something up at the DOS level or Assemble something that uses COM1 as the console (bypass the monitor card). My versions of PROCOM don't have 110b option, but I think you have to do more than just find a terminal program with 110b to make this work. Will update progress asap.

MODE COM1:110,N,8,2
CTTY COM1

...something like that.

bd
 
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Maybe the issue here is that 110 does not exactly divide into 115,200. The 115,200 value comes from the 1,843,200 UART clock rate divided by the divide-by-16 factor of the UART. So a communications program could give you a choice of 300 baud, for example, with a exact divisor of 384, but there is no exact divisor to yield 110 so maybe that is why that choice may not be offered by some software

A divisor of 1047 would yield a baud rate of approximately 110.03, which I imagine should be close enough for your purpose.

I just checked a copy of Kermit-95 version 1.1.17 I have running on Windows XP and it does allow the choice of 110 baud.
 
Nah. Why have a current loop option jumper on the serial card and then not allow 110 baud?

The IBM's async card is unique because it can switch from RS232 to 20mA current loop with jumpers. That's why I want 110 baud. The Asynchronous Communications adapter software (which I now have and have used) has 110b option. Kermit 95 might have 110 baud, but would not work on an IBM XT.
 
A simple BASIC program is probably the asiest way. You want to check for keyboard input while you're reading characters because you don't know what or if a specific character signals the end of the tape. BASIC and MODE still support 110 bps on DOS, the last time I checked. You should be able to do the whole thing in 20 statements or less.
 
Can the card go into a Win box? Hyperterm does 110 baud.

If you're just copying a serial stream to a file then even just the DOS COPY command will do it for ya (with the EOF caveat that Chuck mentioned).
 
100 ' BASCOMM.BAS - Charles Petzold
110 OPEN "COM1:110,N,8,2" AS #1
120 OPEN "SCRN:" FOR OUTPUT AS #2
130 IF NOT EOF(1) THEN PRINT #2, INPUT$(1,1);
140 A$=INKEY$:IF A$ <> "" THEN PRINT #1,A$;
150 GOTO 130

Note - According to IBM's async manual it does not matter if you have N,8,1 or N,8,2 when using 110b
I found that this BASIC program only works with DOS 2 and DOS 2 BASIC, not 3.3's.

I suggest anyone reading this use DOS 2 or maybe 2.1 when experimenting with the IBM asyc card if you also need to use the MODE command.

we're really getting obscure here.

-page 681 PC Magazine DOS Power Tools


THEN, if everything is working it's possible run and exit the program. It will still be active I think. You can then assign the console to COM1

CTTY COM1

And in theory operate the IBM XT "remotely" using the teletype. Not sure if you need a null modem adapter. Still need to check this out.
 
billdeg said:
...And in theory operate the IBM XT "remotely" using the teletype. Not sure if you need a null modem adapter. Still need to check this out.
Click to expand...
I don't get why you want to 'operate the IBM XT "remotely" using the teletype' if you're storing a serial data stream over the same port, or why you'd want a "null modem" if you're using current loop...

Don't see why that BASCOMM program wouldn't work in all DOS versions; which BASIC are you using?
 
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