Electronics > Repair
Vintage chip Programmer : " Micropross ROM 3000U "
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Vince:
Looks like the site MK already showed me... at first I dismissed it because it looked like to me like it was only about enabling a very specific feature, 240 pixel vertical resolution, and that was it. It looked like neither the S/W / project nor the board, were capable of modifying every aspect of the video signal. Plus, I am not a F/W engineer, nor a video protocol guru, so even if the board were capable of arbitrary timings, I would not be competent to make use of it...

But I looked at it again and it looks like I was wrong... there seems to be a user friendly interface to let you repurpose the video chip, and it has presets for NTSC and PAL signals.... i.e stuff that's even farther from CGA than my signal is.... so maybe there is hope for me as well.   OK OK.... I will keep that in mind, will look at it in more detail at some point...


Anyway, some good news : I did what I said I would do... I added a XOR gate on the breadboard to create a composite SYNC signal, as per what I saw on YT.
Well, my old book on logic gates says there are somehow only two TTL chips that do XOR ... 7486 and 74136... with my usual luck, despite having a broad collection of crusty TTL chips.. I didn't have any of these two !  :palm:  I didn't feel like using multiple chips to cobble together my own XOR gate either, too much mess on the bread board and not enough Dupont wires.
So instead I went for the next candidate : XNOR gates. Book says there is only ONE chip that does it... 74266. Well I DO have a few of those !  :-+
Problem.... it's got an open collector output !  :palm:  Would that output be good enough to handle my sync signals without "deteriorating" them to the point that it might upset the video chip... and what resistor to use to get optimal signal shape ?!  More headaches in perspective, grrr...
I let destiny do the math for me : a 3.9K resistor happened to be on the breadboard from a past experience I guess. Good enough I thought, so I used that and scoped the output... perfectly square signals I was greeted with, what a relief !  :phew:

So I connected that to the video board, and hey presto, much better now !!!  :)

As I thought, it now works well enough that it's usable, but not quite perfect because it's not CGA, only close to it.

So, what do we get in exchange for our XNOR gate ?

1) The board is now reliable. It never freezes, not even once. So the F/W must have been upset by my separate sync signals I guess. Poor F/W it is.

2) The AUTO push-button now works : as soon as I press it, the red LED next to the MCU, blinks for 3 or 5 seconds while it's trying to figure the sync signals out.

3) Once that's done, I get a meaningful  and stable picture, woohoo...


The horizontal side of things is working well, as I hoped, because at 15.4kHz it's close enough to CGA for the chip to make the effort.
So I was able to adjust the horizontal position of the picture to center it on the screen, and adjust the size.

However as I anticipated, the vertical sync is too far from CGA, so it kinda works but not perfectly.
The vertical position control behaves weirdly. The best / most useful I could get for a picture, is to get the bottom area of the screen, where the menu bar is, to roll over and display instead at the top of the screen. If I try to put it at the bottom, and I can't achieve it anyway, it destroys the picture.
So now I have a stable and usable picture. Menu bar is at the top instead of the bottom but who cares... let's just  say I customized the F/W in the  programmer to suit my particular taste !  :-DD

So now I can watch the entire boot process and see exactly what's going on. It's just... so cool.  8)

This is what we see :

1) At power up, displays logo and "Insert system disk and press F1", and the leftmost "button" in the menu bar is active and shows "BOOT", which ads up.

2) That lasts only a split second, so I had to remove the system disk from the floppy drive to force the machine to stay in this state so I would have time to take a pic of it and a video clip. That's why it says "Failed" with some error codes... it can't find the floppy in the drive.






3) There is  line of text in reverse video that blinks, this is what I thought might be a blinking cursor a weeks back when I was first watching at the signal in the time domain on my scope. It's more than just a cursor then.

4) I was right : the programmer thinks it is a full fledged model 5000 rather than the humble deaf and mute model 3000 that it is ! Really interesting, that.

5) OK so then I insert the system disk and reboot it so it can actually boot from the drive. It reads the disk for about a minute, during which the blinking text reads " REVISION 5.40AP ".  Also, the menu bar contents change : the "BOOT" option on the left is gone. Now the only button available is the rightmost one, which reads "ABORT". Ads up... first you press F1 to boot, then while booting you can abort the boot process.

Then in the video, at T = 1min14s or so, the drive stops working (I turned off the sound in the video, sorry you can't hear the drive working to make the video less boring)) , boot process is complete. At that point the blinking text now VERY BRIEFLY says " ERASING MEMORY  ".

6) Then the logo and text disappear, screen is cleared and we get just the menu bar at the bottom, well the top here sorry. Again only available menu option, still the rightmost, that says " END ". Underneath the menu bar, it reads " REMOTE CONTROL ".



Now in video :






So how cool is that ? It is SUPER cool !  >:D  :box:


Even cooler : that French forum is cool too, lots more people active in there than I would have imagined !
I have had already two people reply, and those two actually have a 5000 model and both live not too far from me (100 / 150kms away), and we are thinking of setting up a gathering at my place with their 5000 so I can see this beast in the flesh and do some reverse engineering in my lab  8)

Maybe this spring. Some time anyway.
Robert763:
Well done Vince!
Now you need a 5000 system disk!
The most important thing to find when you see a 5000 is what the keyboard is. It could br a dumb matrix, An IBM "PC" or "AT", A serial RS232 or something special.

Robert.
Vince:
The guys on the French forum last night sent me several 5000 boot disk images... so I am covered. From what I understand there were several revisions of the 5000 model, and not all system disks work on all variants of the programmer... and god knows if any work on my 5000 wannabe 3000 model !  :-DD

But I can just try them all and see what happens, no worries.

The real issue is that making these disks is a chore, a whole can of worms, an adventure in its own right... many people tried and only one succeeded, but he first and last posted 2 years ago... hopefully he can still be reached. He did give some info on how he did it, but basically the problem is that just like everything in this programmer, the disk too is custom... Basically you can't read it as is, on a regular PC. It uses a special format. From what I understand, said an engineer who worked on this design back in the day, and who posted on the thread in 2014... it's a regular PC format but it uses 256 bytes blocks instead of 512, something like that, don't quote me...
A guy who posted in 2020 seemed well versed in exotic floppy formats, so he managed to do it and found it easy but... I am not him.
I think he said that he first had to convert the disk image file to some other format, which he could then use with an MS-DOS based S/W that can do very low level stuff on floppy disks, and let you customize each and every parameter. So you better know what you are doing... He posted screen captures of that S/W. Below.



Also said IIRC with that low level stuff that's required... not all floppy drives are equal... some will work others won't. It's pot luck. Well he also knows enough that he picked a random drive from his junk box, and modified the electronics of it to get it to work... I am not at that level...
Also, IIRC you need DD disks, not HD. So first need to find those, and hope they are in good shape...

So I will work at it for sure, but it's gonna be a tough fight I anticipate, and will require many hours on my vintage PC, which I need to excavate... and I have zero space right now to install it anywhere... OK maybe I can buy a cheap foldable camping table and install it in my bedroom, to keep company to some of my boat anchors... but that's a bit extreme...


Now as for the K/B... the situation is even worse I think...
Now that I now more about these programmers, and read the manuals for the 5000 model.... I have to revise the theories I made very early on when I was totally clueless.

Before, I thought may be the two serial ports were meant to connect to the remote desktop computer with one port, and use the other to attach a K/B for local operation. It does not hold water any longer.

The much more likely scenario now, is that this machine is meant 100% to be remote controlled, no K/B envisaged for that second serial port. Instead, that port is I think used to control another programmer. the 5000 manual says that these programmers can control other programmers via that second serial port, in a master / slave fashion.

So out with the idea of an external K/B that would use some RS232 standard somehow, that I could buy off the shelf. No.

It's clear the only K/B this programmer was ever meant to be used with, is the one that's built into it, which is obviously proprietary if just by the looks of it... and the 5 custom functions keys to begin with, that match the 5 boxes in the menu bar on the screen.



When the guys visit me with their 5000, at least one quick simple thing we could try, is to extract the K/B from their programmer and see if I can plug it into my programmer, see if that works... if it does, maybe try to reverse engineer the electronics and signals on the connector, snif some signals with the scope, to at least get an idea of what it's like... maybe it miraculously uses a standard protocol / interface, and only the physical presentation of the K/B is custom.... but somehow I doubt that. Just like they made a custom video interface because it was more convenient for them.... there is no reason why they would not make their own K/B interface if that was simpler for them. But maybe I could design an interface to get a standard PS/2 or old serial K/B to work with their custom interface. But that would take a lot of R&D and reverse engineering time, so I would need a 5000 unit to stay home with me for many months.. they aren't gonna let me do that of course...

Yeah... this programmer is a huge PITA isn't it ? It fights hard every step of the way... nothing comes easy  :scared:

OK so the next steps for me then, must be :

1) Try to setup my vintage computer in a semi permanent manner so I can work on it for a few weeks or months, while I am fighting to write the disk images to an actual floppy.

2) Look into that video board F/W customization UI, to see if I can sort out the vertical sync problem... because I just realised, looking at others pics, that errors codes and error messages are sometimes displayed right above the menu bar... and since the bar is at the very top on my screen... I can't see these codes and messages if any... that's a problem. >:(

3) When I get to meet with the guys, do some reverse engineering work on the built-in K/B. So that won't be before spring at best.


Oh boy.... lots of work ahead...
TERRA Operative:
I know that DOS software. I was using it to create disk images for my HP 4155B Semiconductor Parameter Analyzer a little while back. :D
Luckily now I have one working disk, the machine can make its own copies...


Good luck on the reverse engineering, I'll be watching with interest. :)
pcprogrammer:

--- Quote ---Yeah... this programmer is a huge PITA isn't it ? It fights hard every step of the way... nothing comes easy 

--- End quote ---

Wouldn't be fun if it was easy.  >:D

I have seen a youtube video made by Adrian Black of Adrian's digital basement where he uses that software to make some disks for some old computer.  Will see if I can find it again. He also uses some, a bit more expensive, video converters which I wrote about earlier in this thread. Those converters can be set to proprietary settings to handle almost any video stream.

An idea to see if your programmer is the same as the 5000, is to swap the boards when the guys with the 5000 come over to play. Maybe there is also an option on their machine to duplicate the disks.

Keep up the good work. It is fun to read about it.  :-+

Edit: Found the video. Around 34 minutes in he starts using the disk software. Imagedisk 1.18 might be from here http://dunfield.classiccmp.org/img/index.htm

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