sergey
Veteran Member
Hi,
I am wondering if anyone has/had the original IBM PC 5150 working with Trident TVGA8900 or TVGA9000 cards? How about IBM XT? (Not clones).
Michael and I made a weird discovery that TVGA9000i based card that I designed doesn't work in IBM PC 5150/Retro-PC, but it appears to be working in XT systems (or at least Turbo-XT clones). I tried some other Trident cards (TVGA8900D, TVGA9000A), and they also don't work in my 5150 motherboard...
Is it possible that something on PC bus is different from XT bus that will make card not to work? If I remember correctly bus control signals (/IOR, /MEMR, /IOW, /MEMW) have termination resistors in PC, but not in XT. Also in PC 8259/PIC data bus is connected directly to the CPU, while in XT it sits on the X-bus, behind ISA. Any other ideas?
What it is not:
- It is not 8088/V20 compatibility issue. Trident cards will work with either one of them (on XT systems)
- Most likely it is not a BIOS issue. Other VGA cards work with my 5150, and Retro-PC uses ERSO-like BIOS.
Thanks,
Sergey
I am wondering if anyone has/had the original IBM PC 5150 working with Trident TVGA8900 or TVGA9000 cards? How about IBM XT? (Not clones).
Michael and I made a weird discovery that TVGA9000i based card that I designed doesn't work in IBM PC 5150/Retro-PC, but it appears to be working in XT systems (or at least Turbo-XT clones). I tried some other Trident cards (TVGA8900D, TVGA9000A), and they also don't work in my 5150 motherboard...
Is it possible that something on PC bus is different from XT bus that will make card not to work? If I remember correctly bus control signals (/IOR, /MEMR, /IOW, /MEMW) have termination resistors in PC, but not in XT. Also in PC 8259/PIC data bus is connected directly to the CPU, while in XT it sits on the X-bus, behind ISA. Any other ideas?
What it is not:
- It is not 8088/V20 compatibility issue. Trident cards will work with either one of them (on XT systems)
- Most likely it is not a BIOS issue. Other VGA cards work with my 5150, and Retro-PC uses ERSO-like BIOS.
Thanks,
Sergey