1980s_john
Experienced Member
Hi,
I've had a Model 4 for a couple of years, but couldn't get the floppy drives to work (it ran Basic in ROM fine). The machine always tries to boot a disk from drive 0 (thanks to Lorne for help with sourcing a boot disk) but it would always fail with 'ERROR' displayed.
I took the machine apart to get to the drives, and took them out of the machine. Both looked fine, I see they are single sided (so the double sided Tandon drive I had as spare wasn't an ideal replacement). I resolved the problem by swapping over drive 0 and drive 1, and the machine boots fine on the new drive 0. What I don't understand is how the drive numbering is set-up, as I didn't have to change any jumpers and I couldn't see a twist in the cable. Please can someone clarify how the machine determines which drive is 0 and which is 1.
Also it looks like there is space for a terminating resistor on the the last drive on the cable but none is fitted - is this correct?
Sadly after about 15 minutes the computer gave off a puff of magic smoke so I powered it off without managing to run much more than booting into NewDOS and TRSDos. Luckily it looks like just an X capacitor on the PSU, and also one of the smoothing capacitors is starting to bulge so I will replace that too, and hopefully carry out some more cleaning on the faulty drive (which is now drive 1).
The machine has 64K of RAM, I see there are 8 empty RAM sockets plus some jumpers and I assume 128k is an easy upgrade. Question though is why, what is the benefit?
Regards,
John
I've had a Model 4 for a couple of years, but couldn't get the floppy drives to work (it ran Basic in ROM fine). The machine always tries to boot a disk from drive 0 (thanks to Lorne for help with sourcing a boot disk) but it would always fail with 'ERROR' displayed.
I took the machine apart to get to the drives, and took them out of the machine. Both looked fine, I see they are single sided (so the double sided Tandon drive I had as spare wasn't an ideal replacement). I resolved the problem by swapping over drive 0 and drive 1, and the machine boots fine on the new drive 0. What I don't understand is how the drive numbering is set-up, as I didn't have to change any jumpers and I couldn't see a twist in the cable. Please can someone clarify how the machine determines which drive is 0 and which is 1.
Also it looks like there is space for a terminating resistor on the the last drive on the cable but none is fitted - is this correct?
Sadly after about 15 minutes the computer gave off a puff of magic smoke so I powered it off without managing to run much more than booting into NewDOS and TRSDos. Luckily it looks like just an X capacitor on the PSU, and also one of the smoothing capacitors is starting to bulge so I will replace that too, and hopefully carry out some more cleaning on the faulty drive (which is now drive 1).
The machine has 64K of RAM, I see there are 8 empty RAM sockets plus some jumpers and I assume 128k is an easy upgrade. Question though is why, what is the benefit?
Regards,
John