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Unique S-100 computer (Z-80/Vector Graphic/Micropolis)

deramp5113 said:
From what I recall, you can get the measurements while it’s stuck in the loop trying to boot.

Mike
Click to expand...

I performed the Center Frequency Test (2.1.2) - it was pretty close, but made a minor tweak. Same for the 2us Single-Shot Test (2.1.3) - it was off by a little bit so I made an adjustment. I tested this during a boot attempt.

However, for the 1us Single-Shot Test (2.1.4), I am not seeing any activity on the scope for A14, pin 3. What do you think might cause that?

Tried writing another disk for the heck of it, same result.
 
deramp5113 said:
Looks like the pin number is wrong in that version of the manual. Look at pin 13, not 3.

Mike
Click to expand...

Thanks, that was it! So I adjusted that one (I think it was pretty much dead on already)... tried creating a disk in both drives.. same result - "Write failure on track 0, sector 7"
 
Going through some of the other troubleshooting steps. I've verified voltages and the bootstrap prom checksum. Would it be possible for you to send me an MDOS disk with the "DIAG" command to carry out the rest of the read/write troubleshooting tasks? or is there anything else I could try?
 
nullvalue said:
Going through some of the other troubleshooting steps. I've verified voltages and the bootstrap prom checksum. Would it be possible for you to send me an MDOS disk with the "DIAG" command to carry out the rest of the read/write troubleshooting tasks? or is there anything else I could try?
Click to expand...

I'm sure these are discussed somewhere in the thread, but let's double check the following:

1) You're using hard sector disks with 16 hard sectors (not 10, not soft-sectored)
2) The write protect notch is not covered.
3) You're inserting the disk with the label side up (based on the picture I see of your drive)

Mike
 
deramp5113 said:
I'm sure these are discussed somewhere in the thread, but let's double check the following:

1) You're using hard sector disks with 16 hard sectors (not 10, not soft-sectored)
2) The write protect notch is not covered.
3) You're inserting the disk with the label side up (based on the picture I see of your drive)

Mike
Click to expand...

1) Yep I purchased a box of these - fresh out of the shrink-wrapped box, I have tried 2 different disks from the box so far - https://www.ebay.com/itm/16-Hard-Se...e=STRK:MEBIDX:IT&_trksid=p2057872.m2749.l2649
2) Write protect notch is not covered (and "File Protect" dot is not illuminated once disk is inserted)
3) Yes I am inserting the disk label-side up (as I insert, the write protect notch is to the left)
 
Yep I have tried both drives - the appropriate drive spins up like it's going to write (head locks down, hub spins), but both end up throwing the same error)
 
Read problems are more common than write problems because reading is a much more complex process than writing. That’s why we checked reads first. Of course, you could just have a write problem, and since the most obvious read adjustments aren’t helping, let’s look at write issues next.

You can start by trying to test and troubleshoot the write paths, or I can send you some bootable disks. The good thing about starting by writing your own disks with PC2FLOP is you bypass drive alignment problems since you’re writing and reading with the same drive. But if you can’t write your own disks and you need to use a disk written by someone else’s drive, now drive alignment becomes a new source of problems. It may be quicker to try and troubleshoot the write path and maybe something obvious will jump out.

Let me know which way you want to go.

Mike
 
That's fine with me trying to troubleshoot write operations - how would I test write paths?
 
I would normally start looking on the drive PCB first, but your drive cabinet has a single board that controls two drives instead of a board per drive. I only have schematics for the latter. Have you found and downloaded schematics for the PCB in your drive cabinet? If so, point me to it and I’ll download a copy.

Mike
 
Actually, before we look for a write issue, have you looked at the 60hz strobe lines on the hub disc? How is the drive speed?

Mike
 
Actually I just realized I hadn't tried something after my adjustments.. I was never sure which head connector went to which drive on the internal board. Every test previously I'd swap the connectors around in case they were backwards. So now I swapped them and I was able to get a successful write! It said the disk was created at the end. I wrote the 56k "Vector CPM for Micropolis.vgi" image. However, I am unable to boot from it using the 'B' monitor command. The disk drive engages but just spins and nothing happens.

How would I check the strobe lines? The speed seems ok but how can I measure it? The belts do seem a bit loose.
 
Look on the hub pulley. Is there a strobe pattern printed on a white disk? Just watch in a room with (ideally) fluorescent lights. It should appear to stand still while the motor spins. Most likely it will appear to move forward or backward slowly. You can then adjust a pot on the board in the drive cabinet as detailed in the manual you posted the link for to make the pattern stand still.

Mike
 
nullvalue said:
However, I am unable to boot from it using the 'B' monitor command. The disk drive engages but just spins and nothing happens.
Click to expand...

The manual you posted has the connector information so you can know for sure in future.

If PCFLOP was able to write and verify the disk, then it should boot unless you have RAM problems. Use the monitor to test RAM from 0000 to DFFF and let it run for a while.

Mike
 
deramp5113 said:
The manual you posted has the connector information so you can know for sure in future.

If PCFLOP was able to write and verify the disk, then it should boot unless you have RAM problems. Use the monitor to test RAM from 0000 to DFFF and let it run for a while.

Mike
Click to expand...

Yes, very odd that I could run the disk creation but that I couldn't boot. How long does boot from disk typically take? Just a few seconds, right?

I let the memory test run for over an hour. From what I can tell, I got 0 failures: 20200524_095448.jpg

Yes there is a white disk with a strobe pattern. I will attempt the speed test.
 
So I put the drive under florescent light and attempted the speed test. There is just a blur of the wheel, no appearance of a slow spin or standing still. I adjusted the pot (tried both the top and bottom) and no adjustment seemed to make any difference whatsoever.
 
It has to be a 'real' oldskool fluorescent, not a newfangled compact fluorescent (CFL) bulb, or you could try an LED powered from a low-voltage AC power brick through a resistor.
 
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