ModelTRS-80 Model 4
YearMarch 13, 1985
Number27216
Configuration  64K, 2 FH Drives

Condition on Arrival:

The unit was a bit dirty but in otherwise very, very good cosmetic condition. There was no discoloration and fewer than normal scratches. A couple of the keys were a bit "sticky" when pressed. I didn't want to just power her up, because as I lifted and tilted the unit, it sounded "crunchy". Pieces of something were floating around inside. I needed to inspect further before plugging it in.

The first thing to notice when inspecting the bottom of the machine was the DB-25 connector pointed toward the rear of the unit. This is the Model 4's RS-232 port. On an older Model 4, this connector points straight down rather than to the back. Therefore, this is a Model 4 Gate Array computer. These were later models that utilized a motherboard designed around Gate Array components.

Upon removal of the cover, the reasons for the "crunchy" sounds became obvious. In addition to a small wire floating around inside, and a piece of duct tape, there were two pennies. Yikes! This points out again why an internal inspection of newly acquired equipment is so important before powering it up for the first time. You'll also note the date of manufacturing stamped on the inside of the monitor portion of the unit.


After removing the floating objects from the inside of the computer, I made sure the unit was turned off (switch in the back position on these units) and plugged it in. It powered up great. The image on the screen asking for a diskette was bright and crisp. The brightness and contrast knobs worked well. They were smooth, linear and had a good range.

The next step with this machine will be to clean and test the floppy drives. I really recommend cleaning the drive heads before testing them. That way you don't damage the disk you put in them and you don't mistake a dirty head for a bad drive. I'm going to defer this testing for later and will update this page. The inside of the machine is also filty. A proper cleaning will require a nearly full disassembly.

There's also the issue of the sticky keys. The ENTER key is the worse. The @ key is the only other bad one. This will require further inspection. Overall, though, the machine seems in pretty good shape. It's certainly in servicable condition.