Sound blaster pro ii & cdrom on a xt

Anonymous Coward said:

I guess my v30 motherboard is just weird.

Click to expand...

How many MHz are it? The problem on 8088 based system (your's is 8086 based) might be that the computer is to slow to handle interrupts fast enough, causing a stack overflow and system failure. (the situation is actually that the system gets an interrupt before it is done executing a current interrupt. An example is if the driver makes the card sending the same interrupt multiple times, and the CPU doesn't get as far as telling the card to stop before the next interrupt appears, causing an evil loop and serve stack overflow.)

Can you provide a picture of your MoBo? or Model and manufacter? I doubt you got schematics, but it would be fantastic if you did.

*Edit*
I see, a clock speed of 10MHz with a processor using a more effective fetching technique does dramastically increase the peformance of the system. Maybe it's just the speed of the 4.77MHz 8088 in the original XT that's causing problems (see above).

BTW, I read somewhere that modifying the RAM refresh counter so that it doesn't refresh THAT often will also help a lot, maybe it will work after doing that (what else do we got INT 19h for?). But then there might be 80186 codes.

I've programmed an SB Pro in a 4.77MHz machine and interrupts are not a problem.

I'm surprised this thread is still going -- I thought it was established that the CDROM portion of an SB16 is on the 16-bit part of the card and won't work in an XT.

Trixter said:

I've programmed an SB Pro in a 4.77MHz machine and interrupts are not a problem.

I'm surprised this thread is still going -- I thought it was established that the CDROM portion of an SB16 is on the 16-bit part of the card and won't work in an XT.

Click to expand...

I don't really know much about the CD-ROM part of the card, or if the interrupt routines in the CD-ROM driver is longer than the ones you have been using.

As of I know,

On the SB pro 2, the 16-bit part consist of:
Two power lines, VCC (+5v) and GND
IRQ 10 line, directly tied to the "IRQ 10" jumper.
DRQ 0 and DACK 0 tied directly to their jumpers.
all three of therse jumpers are optional on .
Because of this, it should theoretically work (at least with a V20), but for some reason it doesn't.

There was more than one version of the SB16, but all of them usually uses the extra data and adress lines of the 16-bit partion of the card, so that doesn't work 100% in an 8-bit slot. I agree that the CD-ROM partion of therse cards problably doesn't work in an 8-bit slot (at least not IDE).

Here's the V30 board I'm using. It's made by Juko...very fast.

I have a lot of SB16s. I'll have to try one out when I have time to see if the CD-ROM portion works in this machine...one of the models using the proprietary interface of course.

yesterday i installed my old SB Pro 2.0 in my tandy 1000tx. yes it's a 286, but the memory and data bus are 8-bit. it's basically an 8088 system with a 286 chip rigged up in it.

i connected my ancient CR-563-B to it and the machine picks it right up in the 8-bit slot. since it works on that system, the only reason it wouldn't be able to work on an XT-class machine is if the driver has 186 or newer instructions anywhere in it.

i have the card jumpered for IRQ 2, DMA 1, port 220h.

Anonymous Coward said:

Here's the V30 board I'm using. It's made by Juko...very fast.

I have a lot of SB16s. I'll have to try one out when I have time to see if the CD-ROM portion works in this machine...one of the models using the proprietary interface of course.

Click to expand...

Try to remove the blue jumper and try it then. Does it still work?

When the blue jumper is on, the card runs at 12 or 15 MHz, when off, 4.77MHz, according to TH99.

Mike Chambers said:

yesterday i installed my old SB Pro 2.0 in my tandy 1000tx. yes it's a 286, but the memory and data bus are 8-bit. it's basically an 8088 system with a 286 chip rigged up in it.

i connected my ancient CR-563-B to it and the machine picks it right up in the 8-bit slot. since it works on that system, the only reason it wouldn't be able to work on an XT-class machine is if the driver has 186 or newer instructions anywhere in it.

i have the card jumpered for IRQ 2, DMA 1, port 220h.

Click to expand...

Can somebody try to dissasemble the driver? If it's using one of the additional 2-byte "0F..." op-codes, it will result in an "POP CS" and then execution of random stuff due to segment change on an original 8088/8086. If the top of the stack actually IS the same as the current CS before the op-code, the processor will try to execute the other half of the 286+ op-code, and gets unsynconized with the actual code.

It should be possible to patch the driver somehow.

I'll try your 4.77MHz theory for you the next time I open the XT for maintenance. Right now everything is neatly packed away. At some point I'm actually going to hard wire a reset button and a turbo switch.

The description on TH99 is likely an error. For the longest time I believed this was a 15MHz board, but I'm pretty sure it's 10MHz with the jumper closed.