I'd think that, as long as you don't use the 16-bit DMA (AKA High DMA, HDMA), it should work fine under Sound Blaster Pro (or lower) mode

what use hdma for example?

Just don't use DMA 5, 6 or 7.

Ok, but i not understand pratically what kind of limiting i will have in a Dos 6.22 gaming machine

You won't be able to use SB16 in any game for digital audio. Just run DIAGNOSE utility of the SB16 installation, and enjoy the errors.
Running in plain SoundBlaster/SBPro should work though. Games that support SB16 are many, mostly from the CD era, like Full Throttle, Crusader No Remorse, Wing Commander 3/4, Syndicate, Extreme Pinball... SB16 mode offers much better audio quality under these games.

Ah ok, i will solder the extra 16bit slot…. thanks a lot

AlessandroB wrote on 2025-02-11, 12:10:

Small note: I also tried an Adaptect 1542CF but it doesn't seem to give any sign of life (the card works perfectly inside a 486).. maybe this card needs the contacts of the entire isa slot

That's exactly true. The key selling point of the Adaptec 1542 in comparison to cheaper and simpler SCSI adapters is that the 1542CF has its own CPU and manages execution of SCSI commands in the background while the 80x86 ("host") processor can do other stuff (doesn't help if all "other stuff" waits for data from the SCSI bus, though). The primary communication channel between the Adapter 1542 CPU and the host CPU is that the adaptec 1542 can access the memory of the host CPU to get the commands to be executed, obtain data to be written to SCSI devices and store data received from SCSI devices. The I/O ports are mainly used to reset the 1542 and to "ping" it that it should check for commands, and the IRQ just triggers the 1542 driver on the host to check the command status in memory.

The signals that allow the Adaptec 1542 to get access to the host memory are on the 16-bit part of the ISA slot, so the card plainly can not work without a full slot.

mkarcher wrote on 2025-02-11, 17:17:

AlessandroB wrote on 2025-02-11, 12:10:

Small note: I also tried an Adaptect 1542CF but it doesn't seem to give any sign of life (the card works perfectly inside a 486).. maybe this card needs the contacts of the entire isa slot

That's exactly true. The key selling point of the Adaptec 1542 in comparison to cheaper and simpler SCSI adapters is that the 1542CF has its own CPU and manages execution of SCSI commands in the background while the 80x86 ("host") processor can do other stuff (doesn't help if all "other stuff" waits for data from the SCSI bus, though). The primary communication channel between the Adapter 1542 CPU and the host CPU is that the adaptec 1542 can access the memory of the host CPU to get the commands to be executed, obtain data to be written to SCSI devices and store data received from SCSI devices. The I/O ports are mainly used to reset the 1542 and to "ping" it that it should check for commands, and the IRQ just triggers the 1542 driver on the host to check the command status in memory.

The signals that allow the Adaptec 1542 to get access to the host memory are on the 16-bit part of the ISA slot, so the card plainly can not work without a full slot.

Thank you very much for the beautiful explanation!