Tronix
Experienced Member
Hello,
I recently got this motherboard (photo by seller):
I identified the board as AUVA COMPUTER 8088 TURBO TXM/10-III . I washed the board from dust and dirt, straightened the jumper contacts and installed the jumpers of the eeprom type selection in accordance with the description to 2764. Also i set dip switches according manual to 640Kb RAM, no FPU, 1 drives, and VGA monitor type. Then I turned on the board with a VGA video card and there was no image on the screen at all (no signal).
So, i burn in to 2764 EEPROM Supersoft Landmark ROM and start board with old CGA videocard based on discrete elements and got this static image:
At the same time, the speaker beeps the following errors:
- Keyboard controller (yes, keyboard is not connected);
- Floppy controller (yes, floppy controller is absent);
- Floppy disk read (no controller - no disk read);
At some point, LandmarkROM does a "CGA Memory test", and at that moment i can see on the screen "CGA snow" is running but no characters appear or change on the screen. After a while, the errors beeps repeat in a cycle (new pass started).
I have tried different CGA cards - old discrete IC based, newly made CGA Redux, old chipset based CGA - in all cases i get some pattern on the screen instead of letters/normal text. With MDA card (chipset based) Landmark ROM beeps says: "cannot initialize monitor".
If i start the motherboard with the default BIOS and play with the monitor type selection DIP-switches, namely switching from CGA40 to CGA80, then i can see that the CGA card switches to these modes (the size of the characters increases if CGA40 is installed).
So, what i did:
1) Passed the test by the method of "ground I/O CH RDY" - FFFFE sticks out at addresses A0-A19, as it should be, 0xEA sticks out at D0-D7, as it should be.
2) Desolder, raised on IC-panels and replaced the main buffers and latches on the data bus and addresses bus (74F245, 74LS373)
No luck;
3) Desolder, raised on IC-panels and replaced many discrete IC, all 74LS244 buffers and i8237 DMA controller
No luck;
4) Desolder, raised on IC-panels and replaced i8255, i8259 - no luck;
5) Test all memory IC by special tester, found one bad chip, replace it. Nothing changes.
6) Replace i8288 bus arbiter with good one - nothing changes.
Thus, most of the IC on the board were already replaced with known good ones, but this did not bring any result. Everything works, but nothing works.
A PROM chip is installed on the board - U83 marking 82S129 (256x4)
with strange label:
MRO (????) phase phase 1
R (Reset?) phase
I'm not sure that this chip is from this board, and not replaced by someone once. Nevertheless, the firmware from it:
To understand what is happening here, I drew a part of the circuit in the binding of this PROM:
Unfortunately, I can't figure out if this is a normal firmware or not. I don't have enough knowledge.
All firmware (main BIOS and PROM) I attach.
I would appreciate any help, thanks in advance
I recently got this motherboard (photo by seller):
I identified the board as AUVA COMPUTER 8088 TURBO TXM/10-III . I washed the board from dust and dirt, straightened the jumper contacts and installed the jumpers of the eeprom type selection in accordance with the description to 2764. Also i set dip switches according manual to 640Kb RAM, no FPU, 1 drives, and VGA monitor type. Then I turned on the board with a VGA video card and there was no image on the screen at all (no signal).
So, i burn in to 2764 EEPROM Supersoft Landmark ROM and start board with old CGA videocard based on discrete elements and got this static image:
At the same time, the speaker beeps the following errors:
- Keyboard controller (yes, keyboard is not connected);
- Floppy controller (yes, floppy controller is absent);
- Floppy disk read (no controller - no disk read);
At some point, LandmarkROM does a "CGA Memory test", and at that moment i can see on the screen "CGA snow" is running but no characters appear or change on the screen. After a while, the errors beeps repeat in a cycle (new pass started).
I have tried different CGA cards - old discrete IC based, newly made CGA Redux, old chipset based CGA - in all cases i get some pattern on the screen instead of letters/normal text. With MDA card (chipset based) Landmark ROM beeps says: "cannot initialize monitor".
If i start the motherboard with the default BIOS and play with the monitor type selection DIP-switches, namely switching from CGA40 to CGA80, then i can see that the CGA card switches to these modes (the size of the characters increases if CGA40 is installed).
So, what i did:
1) Passed the test by the method of "ground I/O CH RDY" - FFFFE sticks out at addresses A0-A19, as it should be, 0xEA sticks out at D0-D7, as it should be.
2) Desolder, raised on IC-panels and replaced the main buffers and latches on the data bus and addresses bus (74F245, 74LS373)
No luck;
3) Desolder, raised on IC-panels and replaced many discrete IC, all 74LS244 buffers and i8237 DMA controller
No luck;
4) Desolder, raised on IC-panels and replaced i8255, i8259 - no luck;
5) Test all memory IC by special tester, found one bad chip, replace it. Nothing changes.
6) Replace i8288 bus arbiter with good one - nothing changes.
Thus, most of the IC on the board were already replaced with known good ones, but this did not bring any result. Everything works, but nothing works.
A PROM chip is installed on the board - U83 marking 82S129 (256x4)
with strange label:
MRO (????) phase phase 1
R (Reset?) phase
I'm not sure that this chip is from this board, and not replaced by someone once. Nevertheless, the firmware from it:
To understand what is happening here, I drew a part of the circuit in the binding of this PROM:
Unfortunately, I can't figure out if this is a normal firmware or not. I don't have enough knowledge.
All firmware (main BIOS and PROM) I attach.
I would appreciate any help, thanks in advance