Tandy/Radio Shack TRS-80 Model 4

Having just reassembled a TRS-80 Model 4, I must have a quick rant about the way this machine is put together. If anything, it'll be a guide to future Model 4 owners (and the Model 3, presumably). I started off with a working machine but no boot disk. The message I got from the corrupt disk supplied was "ERROR". That's it, no more explanation, just one word. I was lucky enough to find a manual and a boot disk in a secondhand bookshop here in Bristol. So, I decided to try the machine again, but I didn't want to trash the new disk in a faulty drive (see, Tony, somebody's listening!). Take care when opening up the Model 4 because the CRT comes off with the lid, making it heavy and off-balance. The back end of the CRT (with the connector on) is very close to the internal metalwork of the chassis, too, so don't lift the lid off backwards. And don't forget to remove the single bolt from the top of the back of the lid. To get the drives out, you have to remove four bolts per drive. Top drive first, fiddle about with the cables, then the lower (drive 0). All seemed to be OK, so I tried to get them back in again. Turns out that you can't get the bolts back in without removing the power supply PCB. So, with the drives back in, I powered it up. No screen display at all, no "ERROR", nothing. Damn. After a while checking IC sockets and tracing video signals, I put the dud disk back in and got "ERROR", nice and clear on the green screen. You don't get any error message at all if there's no disk in the drive. Now I tried the new boot disk, and sure enough, it worked! First task, set the system date. According to the manual, it only accepts dates up to about 1987! Next, copy that good boot disk before I do something daft to it. I used the "backup" command, followed the prompts and... it failed. The new-looking disk actually has some blemishes on the oxide surface where it's been stored for so long. Oh, and if you try to boot a non-bootable disk, you get a nice friendly message about that disk being a data disk -- now why couldn't they make it say something when there's NO disk?? Finally, the serial port, external floppy disk port and expansion connectors are "convieniently located" on the underside of the machine. -- John Honniball Email: John.Honniball(a)uwe.ac.uk University of the West of England