@retrochallenge – Magic Smoke And Serial Ports

IBM 5140 Convertible

I’ve been trying out the expansion units that came with the 5140 and clip on to the back of the main machine.  One provides parallel and serial ports and the other is for connecting a monitor.  Unfortunately I had a ‘magic smoke’ incident with the later unit after powering up the machine.  It was a bit of an ‘oh shit’ moment as initially I didn’t notice it but caught a whiff of the tell tale stench before spotting the smoke rising from the unit and shutting it down.  I haven’t opened it up yet to see what the damage is but hopefully it’s repairable.

Expansion Bus Connector

Expansion Bus Connector

The expansion bus on the 5140 uses 8-bit ISA architecture.  At the rear of the unit is a single 72 pin edge connector which is repeated on the back of each expansion unit.  Once attached the expansion units give the machine a very odd look, especially if you also attach the printer unit which results in the 5140 almost doubling in length.

Theoretically you could create some kind of hack with an old unit and hook up an HDD but that’s well beyond my level of tinkering.

Serial/Parallel Expansion Unit

The serial port on the interface expansion unit is working.  I downloaded the ever dependable Kermit and after stripping it somewhat to fit onto a 720k floppy loaded it up and dialled out to my BBS and sent off a couple of emails.  It’s been interesting running a machine with no fixed disk.  The second drive by the way has started working, maybe whatever was preventing it from reading disks before has been dislodged.  I made a quick video of the 5140 below:-

I also found the following advert for the 5140 on Youtube, in it you can see the machine hooked up to a monitor, I lust after that monitor, I want one, a lot:-

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