Serial (Port) Killer

This week I killed my ADAM. šŸ’€

I was trying to fix a new issue Iā€™m having where any software that tries to access the serial port is just echoing a series of “D” characters onto the screen. The problem is present in ADAMLink V (EOS) and Qterm (CP/M). My serial port device is an Orphanware/HLM-GLK model which attaches to ADAM’s side expansion port. However I figured out that it wasn’t a problem with my serial port because the behaviour persisted even when I had nothing attached to the expansion port.

I posted about the problem on the ADAM Facebook Group and it was suggested by James Notini that I try connecting my Atari 2600 adapter (ColecoVision Expansion Module #1) to see if its a problem with my expansion port. The Atari adapter worked just fine so I had a bit of fun playing Asteroids while I decided on my next course of action.

I tried removing my memory expansion card. No difference. I tried disconnecting each of my data drives. No difference. I tried using the printer power instead of my new external power supply. No change. Milli suggested disconnecting the keyboard while the “D” stream was appearing to see if it was a keyboard glitch. It wasn’t. At a loss, I decided I would dismantle ADAM to clean out any dust as well as inspect the boards and see if any wires or chips were loose.

This was the first time I had taken ADAM completely apart, removing all the metal shielding (of which there is a lot) and getting right down to the boards. It was kinda fun but a little nerve-wracking as I started to panic that I wouldn’t be able to put it back together again. After all, this is my one and only ADAM computer! šŸ˜¬ Inside ADAM level 1 - ColecoVision Board Inside ADAM level 2 - ADAM Board ADAM's Brain - The Z80 CPU

After cleaning out the dust with compressed air and inspecting the boards I put ADAM back together again and booted up… to a blank screen. A blank screen with a steady sound being emitted to be exact. šŸ˜± What had I done wrong? I must’ve missed reconnecting something. I didn’t have time to take it all apart so I had to leave it for a couple of days until this morning when I made my attempt to bring ADAM back from the dead.

I was methodical. After each part I disconnected I would try to power up ADAM and see if the screen stayed blank. It was when I removed the top metal shielding from the ColecoVision board and powered up that I was finally greeted by ADAM’s familiar word processor. šŸŽ‰ I breathed a huge sigh of relief! I discovered that one of the screws was making contact with the shielding above and the shielding below the CV board which was causing the problem. I removed the top shielding, re-assembled, and I was back in business! Did a RAM test and diagnostic and everything looks good.

Unfortunately the orginal “D” stream serial port problem that started this misadventure still haunts my ADAM šŸ‘» but for now I am just happy to have him alive and functional again!