scsi is a particular rabbit hole. Its not too bad, but there are certain idiosyncrasies to scsi that just sour 9/10 people from it.

As long as you follow the rules religiously, you will be fine.

to give a bit of advice, if you don't need to use scsi, don't. Double so if you have the opportunity to use a pci sata card.

Have to agree.
As your taking about a 386...
If your looking at SCSI for performance, CF/SD cards are a better, cheaper, easier to find.
If your looking for larger disk support, drive overlay or XT-IDE are better options.
If your after reliability, SCSI is NOT what you want! most of this stuff will have come out of servers that ran 24/7 for years on end and SCSI has been out of production for many years now so even NOS will be at lest 10 years old minimum.

Of course if its simply because you want to try it out then go for it, you already have the hardware.
The real basics of SCSI is insert card, assign the HDD and CD different SCSI ID's and a terminator at the end (which you have)
As long as the SCSI card has its own BIOS, it'll act somewhat like your computers BIOS where it'll load during post and you can set any parameters if needed here.

after that it'll comedown to hardware/OS/etc so can cross that bridge when we get to it

Earlier versions of the 1542 have a 1GB limit, not sure if this also applies to the 1522. Either way - any ISA SCSI adapter is going to be a bottle neck on a Pentium board. If you are going to use SCSI on a Pentium 1 use a PCI SCSI card and wide SCSI drives - The AVA-2902 does not have a BIOS, so it won't be bootable. You will be able to use drives connected to it once Windows loads. The 1522 belongs in the 386.

Well, as long as you get all the terminators sorted out, it should work. With recent hard drives (e.g. SCA drive with corresponding adapter), you might get better performance off a SCSI drive as Adaptec ISA SCSI controllers are one of not so many controllers that actually supported ISA bus mastering. Beware, some SCA drives don't support SE (the 50pin cable).
However, I wouldn't expect that much of an improvement, so yeah - if you want to play with it, cool, but it might be easier to stick with IDE 😀
FYI: I do use SCSI drive in one of my Pentium builds. It's an SCA drive connected to PCI SCSI controller (some variant of AHA2940) and it works pretty well - silent as grave and faster than baby after first curry.

Cheers for the input. Thanks for the heads up on a possible 1gig limit. Haven't been able to verify if this is applicable to the AHA-1522 yet. My card bios is dated 1990. The AHA-1522A definitely supports drives bigger than 1gig up to 8gig according to it's manual. Just jumper the second R- on J5. Might try that on this card out of interest. The original drive was an Apple branded 100meg SCSI hdd. The current SCSI hdds I have were pulled from an Intergraph Pentium Pro system used in the Radio industry. Looking back now I should have kept that system but that's in the past. I suspect it originally had NT4 as Intergraph systems were built specifically for this purpose. When I received the system XP pro was loaded on it when I got it.

This is purely an exercise to get familiar things SCSI more than anything else. Found the jumper settings https://stason.org/TULARC/pc/hard-disk-floppy … A-1520-AHA.html and installation guide https://www.manualslib.com/manual/205928/Adap … 520.html#manual

As an aside. Going through my ISA multi i/o card I found my old Promise EIDEPro card I bought in the 90s. Quite a nice piece of kit. Might start a separate thread about it. Appears the win3.x driver disk has disappeared at some point.

I have an adaptec scsi card on my 386 and another one on my p133 machine. In both cases no drivers were necessary either for dos or for windows. The adaptec card does have a bios setup that you can enter at boot by pressing one of the F keys and sometimes you need to do that to tell the card which devices to enable (SCSI supports multiple daisy chained devices) and set the speed, etc. but if you fool around in there it won't take long before the drive detects and functions normally. Apparently "asynchronous" mode can give you extra speed but I didn't notice much difference.

SCSI isnt hard, once you know the rules. SCSI drives themselves aren't more reliable. until 7200+ drives were normal, the physical drive was often the same as the IDE, just a different controller card slapped on its belly. It wasn't until 7200/10k drives did the enterprise and consumer markets really separate. Even then the technology was the same, just a different motor.

The main benefits to scsi are the number of drives per system, and cpu overhead. The latter is great for pre-pci systems. Its not going to be a fps increase, but loading will be smoother, and usually quicker. Once you get to pentium pci, sata is just better in every conceivable metric. I say this and I LOVE scsi.

The downsides to scsi are minimal once you know what you are doing, at least when you are talking about setup. However SCSI drives were often ran 24/7 for a decade, or have sat on a shelf for 20 years. So even though the later ones were generally built better, they were truly USED. So failures are common. I save all my SCSI parts for machines that were made for scsi only. Such as pre-68K Macintosh and IBM ps/2.

luckybob wrote:

The main benefits to scsi are ... cpu overhead.

This does not apply to the AHA-1520.
It has no BM DMA like AHA-154x.

dr.ido wrote:

Earlier versions of the 1542 have a 1GB limit, not sure if this also applies to the 1522.

Yes. The same goes for the 1520. Later BIOSes have a limit of 8 Gb.

retardware wrote:

luckybob wrote:

The main benefits to scsi are ... cpu overhead.

This does not apply to the AHA-1520.
It has no BM DMA like AHA-154x.

Thankfully, cards with DMA are very easy to get ahold of. ^.^

Well finally had a go at sorting out the scsi drives. Had a lot of issues with a 386 mobo I initially tried testing it with. It wouldn't boot ANY hdd, SCSI or IDE no matter what I tried. Switched to a 486 mobo and things went swimmingly. Found a guide for the two Seagate Hawk SCSI hdds I have. The 1.2gig went without issue, The 9.1gig only could be partitioned to one 512meg partition without being able to make extended partitions so need a more modern card for that. Maybe a bios update would sort that out.

Also tried out my EIDE Promise card. Could set up and format a 6gig IDE drive no worries.

Because they are bigger drives I used a Win95b boot floppy to run fdisk and format on both SCSI and IDE dives and formated as FAT32. Very happy with the result.

Also tested an older jumpered nic with xt-ide in rom and that went well too. All in all a great days tinkering.