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

Good tip - I'll check that out. However, the cap was on the Bit Streamer board. The system is not booting even without the Bit Streamer installed. Since I do have some (uninitialized) video, wouldn't that point to a problem being on the 12K PROM/RAM or Z80 CPU?
 
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Traced what I hooked up to. The negative end runs to the VEE pin of a 1488P chip. It's carrying -12v.
 
nullvalue said:
Good tip - I'll check that out. However, the cap was on the Bit Streamer board. The system is not booting even without the Bit Streamer installed. Since I do have some (uninitialized) video, wouldn't that point to a problem being on the 12K PROM/RAM or Z80 CPU?
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It really doesn't matter on what board you cause a power supply short if that short, in turn, damages the system power supply. Though with a 7912 in between the short and the system -16v supply, it would not be typical to get past the regulator in a catastrophic way. The short may have damaged the negative supply on another board.

Measure the system supplies (-16v, +16v, +8v) and see where they are. If they look fine, then look on the boards and check the voltage of any onboard negative supplies and see if they're correct.

Mike
 
deramp5113 said:
Measure the system supplies (-16v, +16v, +8v) and see where they are. If they look fine, then look on the boards and check the voltage of any onboard negative supplies and see if they're correct.
Click to expand...

I checked the rail voltage and it does not appear that I have a stable -16v on pin 52. I'll check it one moment and it's fine (like -18v) and the next it's gone. Guess I'm going to have to replace the power supply or at least part of it? What's the current best approach for doing this?
 
I was testing voltages with load vs no load. Pulled everything out.. put it all back in and what do you know, system is booting fine now and my -16v rail is back.. bizarre. Will get back to serial testing... lesson learned: don't assume negative end of caps are ground!

Edit: I think I found my problem with the power supply - may have been nothing to do with my scope hookup afterall. I think my molex connector supplying power to the backplane is lose. I accidentally wiggled it while working in there and the same thing happened where the screen scrambled. This is a relief, I love simple explanations.

BTW for the serial communications: I did try bumping it up to 9600 baud. Still able to transmit data to the terminal PC, but nothing on the receiving end. (I 06: 00) - will start tracing the signal across the board.
 
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You can quickly check that the input path from the 8251 to the processor is OK by doing an IN 07. Does that give something besides 00?

Mike
 
So after some further testing, I am able to see the data reach the 1489 receiver chip input (pin 10, Input C) but nothing coming out and nothing reaching the 8251. I'm going to order a replacement for the 1489 and cross my fingers.
 
deramp5113 said:
You can quickly check that the input path from the 8251 to the processor is OK by doing an IN 07. Does that give something besides 00?
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20200509_195530.jpg

Another problem solved! After replacing the 1489, I am now able to both send and receive data. So.. you had mentioned something about being able to manually send initialization codes?
 
You won’t need to send init codes. The fact that the manual in/out tests work prove that the PROM monitor initialized the port. I’ll update PC2FLOP to allow use of port 6/7 for transfer and then you can try creating a disk. I’ll let you know when it’s posted.

Mike
 
You won’t need to send init codes. The fact that the manual in/out tests work prove that the PROM monitor initialized the port. I’ll update PC2FLOP to allow use of port 6/7 for transfer and then you can try creating a disk. I’ll let you know when it’s posted.

Mike
 
I've uploaded a new version of PC2FLOP that supports the port at I/O address 6/7 here: https://deramp.com/downloads/vector_graphic/software/disk_image_transfer/Micropolis controller/

Repeat the procedure you performed previously to load PC2FLOP.COM into your machine. Enter the bytes shown in LOADER.PRN starting at address zero using the monitor's "P"rogram command. You'll need to change I/O port address references from 4/5 to 6/7 (i.e., change 04 to 06, change 05 to 07).

Mike
 
deramp5113 said:
I've uploaded a new version of PC2FLOP that supports the port at I/O address 6/7 here: https://deramp.com/downloads/vector_graphic/software/disk_image_transfer/Micropolis controller/

Repeat the procedure you performed previously to load PC2FLOP.COM into your machine. Enter the bytes shown in LOADER.PRN starting at address zero using the monitor's "P"rogram command. You'll need to change I/O port address references from 4/5 to 6/7 (i.e., change 04 to 06, change 05 to 07).

Mike
Click to expand...

Not sure if I've done something wrong or not.. After entering LOADER.PRN, I type G 0000 - nothing happens on the screen. In Teraterm I begin the transfer - about 75% of the way through sending the screen on the S100 goes to all block characters. After transfer, I do a reset, and a D 0100. It's filling with character '87' through about 0134, then seems like the rest of memory is filled with '97'.
 
Ah it appears I modified the LOADER.PRN incorrectly. It seems it is working correctly but I think I'm having a problem with my USB to Serial adapter, partway through sending the file the LED's stop blinking and basically hangs the PC. Going to try adjusting the baud rate etc.
 
Ok so I have managed to transfer the program, 9600 and 4800 baud both seem to be working very well. - I haven't reviewed the transfer byte for byte but it appears correct because I am to see the strings from the program as part of the memory dump. However when I attempt to run (G 0100) I just get this dump.

20200511_103033.jpg
 

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In the dialog box that comes up in the terminal emulator when you send the file, make sure the "Binary" check box is selected.

Mike
 
Ah didn't even see that checkbox, that did it - the program is running! Will try creating a disc later today.
 
Thanks, this is really exciting to see it actually executing a program! I can't get the drive to seek on the first step. I entered 0 <ENTER>, and it'll just say "seek to track 0 failed" - I don't hear the drive spin up or anything. I tried 1-3 also, same results. I attached a picture of how the ribbon cable connects. I highlighted the arrow of the cable which is on the notched side of the edge connector. On the other end of the cable there is a plastic divider so it can only be plugged in one way. Do I have the cable attached the right way? I'm afraid to flip it in case that could cause problems. Or should I just try reversing it?
20200511_141648.jpg 20200511_141700.jpg

EDIT: Also, here is a closeup of the FDC address jumpers in case that may be a problem.

20200511_143930(1).jpg
 
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Well after posting those pictures I noticed the edge connectors looked pretty dirty. I cleaned them up and retried the program. Now when I run the program and enter drive 0, I do hear the drive spin up! I have a brand new hard sectored disk in the drive. However it still gives me "seek to track 0 failed".
 
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