Part 1: No one expects the construction crew
On Call Come with us to the 1980s, when computers cost proper money and RS-232 ruled the roost in another edition of Register reader recollections courtesy of On Call.
Today’s tale comes from “Jeff”, who spent a good portion of the decade that gave us The A-Team, Knight Rider and the IBM PC working in the hotel IT business.
“RS-232 wiring,” he recalled, “was normal between machines.” There was no email or messaging back then, just teletype and faxes, nor was there the remote access or hasty sending of a patch taken for granted today. “A small business computer was size of a washer and dryer and cost around $100,000.”
RS-232 cables were also the bane of Jeff’s existence.
A call came in from a hotel complaining that telephone charges were not making it from the phone switch (located at one end of the hotel) to the computer (helpfully positioned at the other.)
The cables were plugged in correctly and things had been working properly up until now. Naturally, the user was convinced that nothing had changed but still those charges were not getting through.
OK brainiacs, we’ve got an IT cold case for you: Fatal disk errors on an Amiga 4000 with 600MB external SCSI unless the clock app is… just so
Jeff began the troubleshooting process over the phone, kicking off by testing the Async BiSync Converter (ABC) board with the aid of a paperclip.
For those not familiar with the delights of ABC devices, the things were hardware protocol converters, usually with a pair of RS-232 ports (one async and one bisync.) They were often found converting data from one source into something another device would understand. In this case, helping the phone system and hotel computer communicate.
And the paperclip? “Disconnect the RS-232 plug,” instructed Jeff over the phone, “bend a paperclip into a ‘U’, plug into pins 2 & 3, run the test program on the host machine…” A DIY loopback, if you will.
Pins 2 and 3 of an RS-232 plugs are used for receiving and transmitting data (with subtle differences between the original 25-pin incarnation and the “modern” 9-pin versions.)
This hack has fond and not-so-fond memories of making cables for ancient daisy-wheel printers back in the day as well as the odd acoustic coupler. The various types of serial connection remain seared into the grey matter to this very day.
In the case of the hotel, all was OK. The card was good. Jeff delicately asked if “something” might be happening at the hotel. Maybe a new tower was being added?
“No… but they are remodelling the third floor.”
The construction crew had kicked off work that morning and cheerfully sliced through the RS-232 line (helpfully installed without conduit) while demolishing walls.
Jeff’s solution was of the quick and dirty variety. A spool of phone wire was picked up from the local Radio Shack and ran along the floor from phone switch to computer. The ends were stripped, the cores bent over to form a makeshift pin and stuck into holes 2, 3 and 7 of the RS-232 port.
The data was flowing once more.
Naturally, Jeff explained the fix was very temporary, that the cable would need to be placed inside a proper conduit and the correct connectors wired up. “No need!” the user cheerfully responded. “I got the carpet guy tucking it under the rug. We are good!”
What could possibly go wrong?
Tune in next week for the second instalment of Jeff’s adventures in RS-232 with The Mystery of the Million-Dollar Bar Bill.
Ever talked a user through a potentially computer destroying procedure? Or have a particular RS-232 confession that you need to get off your chest? Send an email to On Call and tell all. Just don’t ask us to make you an RS-232 cable as a reward, OK? ®