Electronics > Repair
Vintage chip Programmer : " Micropross ROM 3000U "
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Vince:

--- Quote from: Zoli on October 31, 2022, 02:22:06 pm ---
--- Quote from: Vince on October 31, 2022, 09:47:52 am ---...
- It's got two serial ports at the back , DB25, for I/Os.
...

--- End quote ---
My suspicion: one serial is for computer communication, one for terminal communication; so it would be worthwhile to check for Tx activity on the ports during startup.

--- End quote ---

OK I played in the RS232 department. Here are the results before I fall asleep in a couple minutes probably (it's only 21H40 but well... I don't understand...).

So, I scoped both serial port during power up / boot from the floppy, for activity on the TxD pin.
Zero, nada. Well, I get -10.9Volts. Then I scoped each one of the 25 pins, and some of them have voltage... 4 of them to be exact, same result on both ports :

#4 =  +12V
#5 = +6V
#6 = +6V
#20 = +12V

So at least I know these port run +/-12V signals, that's a beginning... Sure it was to be expected since the PSU gives 12V rails, and it's meant to be connected to a computer which also usually run their RS232 on 12V. But well, nothing prevented them from doing some voltage upping to reach the 30V of the RS232 standard.

So what we also know that clearly the UART uses some of the control signals rather than just RxD / TxD. I guess it was to be expected for such an old device.
I removed the PCB that holds these connectors, from the rear panel, so I could get a closer look at the tracks going to the DB25 connectors.
Indeed many track are routed to them, and they are connected to the backplane PCB via a 20 way ribbon cable. A good part of that is used by the 6 way DIP switches used to configure each port.

Anyway. This means the programmer probably is not set up to send data on its own, at power up, unsolicited. The terminal connected to it, must be expected to ping/interrogate the programmer first, then only the programmer will respond.
Since I don't know the command set, nor what these DIP switches do, how to configure them, what control signals are used and how... it's a bit hopeless trying to communicate....  :(
I mean it's not IMPOSSIBLE... but would require some painful reverse engineering to draw the schematic of that board, what the DIP switches do exactly, then lots of trial and error, trying every baud rate under the sun, combined with ever possible configuration of hardware control and start and stop bits configurations. Oh my god.... maybe one day... but not today.

Some good news though, well maybe : notice how there are two unpopulated connector footprints on this rear PCB ? One is 2x18 pins, could be for GPIB maybe. The other one is 2x8 0.1" header, so could be for a VGA output as far number of pins is concerned. 16 is more than 15.. so good enough. I guess one would need some adpater to connect a DB15 VGA to that header, but maybe the manufacturer provided that...

Now, the two ribbon cables for the serial ports, are connected to the front of the programmer, on the backplane PCB. On that PCB there is a 2x8 header... same as we found on the rear  I/O PCB hmm...; so logic would say that maybe, the video output from the CRT controller on the CPU board, is routed on the back plane to that 16 pin header... so all I have to do is scope that back plane,, easy enough, to see if I see some video action going on....

HMMMMMM !!!!!!


STAY TUNED !!!     >:D >:D >:D >:D >:D >:D

Vince:
Oh boy I could not help I worke don the thing some more, it's addictive, a drug, pure and simple. I should have picked another hobby when I was a kid....

OK so, several things


Benoît Matthieu

He e-mailed me again, saying the shop in Paris is long gone, so no go ! :(
However he did give me the name of that old chap that he knowe and who knew that programmer well. I can try finding him see if he is still with us today...

GPIB

OK so I think that 2x18 footprint on the rear / IO PCB is most likely not for GPIB. As you can see on the picture posted earlier of that PCB, all the traces from that connector are routed straight to the smaller 2x8 header footprint....
also, on the back plane, I have a matching 2x8 heaer but no 2x18 header anywhere.
So clearly, the back plane feeds only the 2x8 connector at the rear, and the 2x18 is just a duplicate that offers the same functionality, just using a different connector.

so this is bad news, it means that this 2x8 header mos tlikely is Not our much desired video output... because  then it would mean there was on the market some video cables using a 38 pin cable ?!  :palm:  Not likely is it.... never heard of it anyway..
In order to confirm that, I scoped the matching 2x8 header on the back plane, and yeah, zero sign of activity on all the pins, nada.

UART

I looked the datasheet for all the big DIL chips on the CPU board, to see what's what.

- MC6845 = CRT controller as was already exposed.
- R6522 = VIA chip, in modern talk  : an I/O chip... contains 2x8 bit ports, 2x16 timers, and some shift registers.
- MB8416, 4 of them. They are 2KB static RAM chips. 2 are next to the CPU, and the other two next to the CRT controller, so probably a frame buffer or something.
- R6551 = the UART.

HOWEVER... what I don't get, is that the datasheet says this chip contains only ONE UART !!!  But we have TWO serial ports at the back !  :scared:
so I guess there must be some multiplexing going on, and the CPU can use only one or the other, but not both at the same time... it must make a choice at some point... so that's quite an important / interesting finding here.

ALSO... I just got a crazy idea to figure out what is the configuration of the UART !!!  Really silly, but hey it's still an idea so it's gonna count for something eh....
Here goes : using a logic analyzer, I could spy the data bus and control signal at the UART chip, at power up, and see how the CPU is configuring the chip ! Spy every write the CPU makes, to see what registers are getting written, and with what value.
No, I don't have a logic analyser.... or DO I maybe !
Remember... the other day I got tha told 54645D HP scope, "Megazoom" ASIC, 2x100MHz .... MSO !! It has a built-in 16 way logic analyzer !!
16 lines is enough to look at th 8 data bus + some control signal ! I could watch the chip enable pin to trigger the scope, then watch the R/W pin and RS / register select  pins. Oh yeah, at last a real world interesting use for "new" HP scope !!!!!!!!!    :box:

VIDEO

I kept the best for dessert of course !!

So if you have been following along, you now know there are two unused connectors / header on the backplane PCB. It's now clear that the 2x8 one goes to the rear IO PCB. But what about the other one ? 1x8 one ? This one no idea where it goes !

So I scoped it anxiously.... and yeah found LOT of activity on there !!! CRT controller is monochrome so the signal were expected to look "digitally". And that what I found !

From memory, out of  pins, 2 show no activity, probably ground, and one is at 12V solid, so probably the 12V supply. But the other 5 pins all have constant activity, trains of pulses,  5V " TTL" of varying content and timing, all perfectly repeatable / stable on screen.... looking GOOD ! Most likely some kind video signal !!!

Sorry can't show you anything, can't hold the probe on the pins with one hand and hold the camera with the other to capture the scope's  display....

It's 00H05 here, I am dying, so tired.

So tomorrow I will plug some old FDD ribbon calbe onto that header (male/female dupont wires would be best but I don't have that...) so that I can  hooke the scope probe ontot those signals and have both hands free to operate the scope, take notes and take pics to show you these signal and have your input.

Can't wait !!!  :D

Once we have the characteristics of all the signals, we can try to figure out what kind of video output standard that corresponds to, and from that we can start coming up with a plan to figure out how to display that signakl onto a monitor !!!  :-+


See you tomorrow !!!

syau:

--- Quote from: Vince on October 31, 2022, 11:07:03 pm ---Oh boy I could not help I worke don the thing some more, it's addictive, a drug, pure and simple. I should have picked another hobby when I was a kid....

OK so, several things


Benoît Matthieu

He e-mailed me again, saying the shop in Paris is long gone, so no go ! :(
However he did give me the name of that old chap that he knowe and who knew that programmer well. I can try finding him see if he is still with us today...

GPIB

OK so I think that 2x18 footprint on the rear / IO PCB is most likely not for GPIB. As you can see on the picture posted earlier of that PCB, all the traces from that connector are routed straight to the smaller 2x8 header footprint....
also, on the back plane, I have a matching 2x8 heaer but no 2x18 header anywhere.
So clearly, the back plane feeds only the 2x8 connector at the rear, and the 2x18 is just a duplicate that offers the same functionality, just using a different connector.

so this is bad news, it means that this 2x8 header mos tlikely is Not our much desired video output... because  then it would mean there was on the market some video cables using a 38 pin cable ?!  :palm:  Not likely is it.... never heard of it anyway..
In order to confirm that, I scoped the matching 2x8 header on the back plane, and yeah, zero sign of activity on all the pins, nada.

UART

I looked the datasheet for all the big DIL chips on the CPU board, to see what's what.

- MC6845 = CRT controller as was already exposed.
- R6522 = VIA chip, in modern talk  : an I/O chip... contains 2x8 bit ports, 2x16 timers, and some shift registers.
- MB8416, 4 of them. They are 2KB static RAM chips. 2 are next to the CPU, and the other two next to the CRT controller, so probably a frame buffer or something.
- R6551 = the UART.

HOWEVER... what I don't get, is that the datasheet says this chip contains only ONE UART !!!  But we have TWO serial ports at the back !  :scared:
so I guess there must be some multiplexing going on, and the CPU can use only one or the other, but not both at the same time... it must make a choice at some point... so that's quite an important / interesting finding here.

ALSO... I just got a crazy idea to figure out what is the configuration of the UART !!!  Really silly, but hey it's still an idea so it's gonna count for something eh....
Here goes : using a logic analyzer, I could spy the data bus and control signal at the UART chip, at power up, and see how the CPU is configuring the chip ! Spy every write the CPU makes, to see what registers are getting written, and with what value.
No, I don't have a logic analyser.... or DO I maybe !
Remember... the other day I got tha told 54645D HP scope, "Megazoom" ASIC, 2x100MHz .... MSO !! It has a built-in 16 way logic analyzer !!
16 lines is enough to look at th 8 data bus + some control signal ! I could watch the chip enable pin to trigger the scope, then watch the R/W pin and RS / register select  pins. Oh yeah, at last a real world interesting use for "new" HP scope !!!!!!!!!    :box:

VIDEO

I kept the best for dessert of course !!

So if you have been following along, you now know there are two unused connectors / header on the backplane PCB. It's now clear that the 2x8 one goes to the rear IO PCB. But what about the other one ? 1x8 one ? This one no idea where it goes !

So I scoped it anxiously.... and yeah found LOT of activity on there !!! CRT controller is monochrome so the signal were expected to look "digitally". And that what I found !

From memory, out of  pins, 2 show no activity, probably ground, and one is at 12V solid, so probably the 12V supply. But the other 5 pins all have constant activity, trains of pulses,  5V " TTL" of varying content and timing, all perfectly repeatable / stable on screen.... looking GOOD ! Most likely some kind video signal !!!

Sorry can't show you anything, can't hold the probe on the pins with one hand and hold the camera with the other to capture the scope's  display....

It's 00H05 here, I am dying, so tired.

So tomorrow I will plug some old FDD ribbon calbe onto that header (male/female dupont wires would be best but I don't have that...) so that I can  hooke the scope probe ontot those signals and have both hands free to operate the scope, take notes and take pics to show you these signal and have your input.

Can't wait !!!  :D

Once we have the characteristics of all the signals, we can try to figure out what kind of video output standard that corresponds to, and from that we can start coming up with a plan to figure out how to display that signakl onto a monitor !!!  :-+


See you tomorrow !!!

--- End quote ---


The floppy disk controller board has a TMS9914 which is a GPIB controller so likely one of the header is for GPIB

There is also 75160 and 75162 GPIB transceiver
Vince:

--- Quote from: syau on November 01, 2022, 12:01:32 am ---The floppy disk controller board has a TMS9914 which is a GPIB controller so likely one of the header is for GPIB
There is also 75160 and 75162 GPIB transceiver

--- End quote ---

Oh, thanks for that, interesting indeed !  :D

I will look into that more closely then, to confirm that this x16 pin header is indeed GPIB, that would be cool !
... another cool thing to investigate, great  :D
Vince:
OK, Matthieu Benoît  e-mailed me again with more info !  He rocks indeed !!  :-+

1) He was mistaken, the programmer he saw in this Paris shop back in the day was not a model 3000U but 5000D... his bigger brother which he remember had a MONITOR along with it !
So yeah, it's now a certainty, there was indeed a higher end model, and all these unused connector headers and foot prints here and there now are confirmed to make perfect sense.


2)  He steered me to a thread on this French forum : https://forum.system-cfg.com/viewtopic.php?t=5743

Thread dates back to 2014 but still... it's pretty much "recent", as far as this programmer is concerned, isn't it...
Lots of little pieces of interesting info in there !
Look there is even one of the engineers who worked on designing this programmer back in the day !  :o :-+

Documentation :

- Someone almost got some : found a web site which was selling this programmer. He asks them about documentation, replied they had some but would charge 100 bucks to photocopy and ship it !  So the guy didn't buy it  :'(

- Someone contacted Micropross directly about documentation, and they did reply !  :D ... .only to say that they "lost"/ scrapped everything they had when they moved building.  :palm:

Floppy Disk :

- They confirm what I envisaged : if I can't read this floppy from my computer, it's not because it's bad/dead (maybe it is, we just can't know at this point !), but it's because it does indeed use a special/proprietary format !

- Someone said that usual floppy copy/imaging S/W on PC's can't handle this format, no joy.

- Someone else said that on some old computers like the Atari 520ST, you had utilities that could make an actual copy of a floppy, i.e disregard any formatting or data structure, and just copy bit for bit from end to end, blindly, whatever is recorded on the disk ! I need that !

- The Engineer from Micropross said that A) the only special thing about their in house disk format is that they use sectors of 256 bytes instead of 512.  and B) They wrote a PC utility in house, so that they could work on their disks using a regular PC.

- People confirm that the machine needs the floppy in order to boot. It's mandatory. You can't just make it work using the serial port connected to a PC. You first need to power it up, boot from the floppy, then connect to the PC.


Operation :

- Someone has a working 5000D unit, with a good boot floppy. He says the unit can be operated STANDALONE. It boots from the floppy and then puts stuff on the screen with menus. One of the options is to make a copy of the boot floppy. However he tried that and when the programmer tries to format the disk, it fails...




Conclusion :

All this good info found only on the FIRST page of this that thread, and there is apparently 5 pages total ! So will read all that and probably learn some more cool stuff !!!  :D


NEXT : looks like two members there, have a working 5000D ! So they could help me I am sure... for example they could maybe help in telling me details about the serial links, how it is configured exactly, H/W control scheme used, what to do with the DIP switches, etc etc...
If the 5000D unit is stand alone,  I guess the extra serial port is used to connect a keyboard ?
That would explain why there the UART chip has only one port inside : either you use the thing standalone hence the K/B connected to one of the serial ports.. or you use it remotely from a desktop computer, hence you can use the keyboard from that computer hence you don't need to use a local K/B. That could make sense...

So we would need to reverse engineer that local K/B interface to see how it works, so I can design an interface to use a regular K/B...

Oh it's fantastic, so many new paths to explore now ! Looks like this is one hell of a vast fun reverse engineering project with many ramifications and child/sub projects ! This bloody programmer will keep me busy for YEARS to come !  :-DD

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