Anything Adaptec that would fit the slot would be good.
Are you using the card for floppy as well or just for HD?

For EISA the Adaptec 2740 /2742 / 2744 family would be perfect.
DOS drivers are also available:
https://storage.microsemi.com/en-us/support/_eol/index.php

Unknown_K wrote on 2022-09-25, 07:51:

Are you using the card for floppy as well or just for HD?

HD and potentially a CD Reader (to consider).

majestyk wrote on 2022-09-25, 08:31:

For EISA the Adaptec 2740 /2742 / 2744 family would be perfect.
DOS drivers are also available: https://storage.microsemi.com/en-us/support/_eol/index.php

If I go for the HD only, will I still need the drivers? I've seen a couple of videos on youtube where the cards seem to work without drivers (for HD only).

Also, is it worth to go for an EISA card? I assume finding an ISA one will be much easier (and cheaper).

Thanks both for the help.

The motivation for using SCSI drives in old systems is a) having higher data throughput and b) being able to use larger drives -compared to PATA drives.

When choosing an ISA controller you still can fulfill b), but the larger data throughput gains that the 32bit EISA bus can provide will not be present.

That´s why I always would prefer EISA if possible, but extreme rarity or sky-high prices can be prohibitive, of course.

Best you can hope for with ISA SCSI (even busmastering) is about 3MB/sec throughput. Go EISA for sure, would be a crime to have it and not use it

Alright... going to follow your advice and look for a EISA version.

Thanks you all for the support.

It may have been released a bit later than the build you have in mind, but I know Creative made a Sound Blaster 16 with a SCSI CD interface.

It was model CT1770.

Re: Gateway 2000 overdrive build

Indeed, find a eisa.

But here is my adventure adding scsi on a 486. Might be of interest.

I don't know any better cacheless SCSI controller for EISA than Adaptec's 2742W/2740W.

I'm using a 2742W (EISA) in a 486 DX 50.
It supports Fast/Wide with up to 20 MB/s.

In DOS, testing a modern HDD I get 12,5 MB/s using BIOS support and over 18 MB/s with ASPI driver.

Note that there are inofficial upgrades for HDDs greater than 8 GB:
INT13 Extensions to Adaptec 274x EISA & 284x VLB
Showing some love for Adaptec's ugly ducklings: Adding big drive support to EISA and VL controllers

Ah, don't buy a 2744 because it is for rarely used high volt differential signaling.
2740 is just without floppy port.
2742W with Wide support is perfect, but 2740W is also good.

My Adaptec SCSI AHA-1542C (the one with the red jumpers switch) work perfectly on my old 386.
Embedded BIOS with fine settings and no driver required.

It took me a while to find the right jumper combination, but I can give it if you take this same card.

edit : ah oh .... yeah expensive today :p https://www.ebay.fr/itm/153521686454

I have found an "Adaptec Aha-2740a/42a/40at/42at" for a very nice price... but I cannot understand if this is a 2740 or a 2742 as the description seems to mention them all 😁

Does anyone know what are the specs of this card?

Cheers,

Note that just the Fast-Wide version with the W has the 68 pin connector and delivers up to 20 MB/s.
The Narrow versions you quoted just have the 50 pin connector and is limited to 10 MB/s.

The 2740W is even cheaper:

https://www.ebay.com/itm/394182991438

I would go all EISA here by all means (except for Multi-I/O, Sound...).

Yes, my 2740W is from same source.
However, I'm using the patched BIOS now with a HDD > 8 GB.

NightShadowPT wrote on 2022-09-25, 06:31:

After many years of placating my nostalgia through the use of DosBox and FPGA solutions, I have finally decided I want to rebuild one of my first computers, a Compaq Deskpro 386DX25, but also want to transform it into the dream machine I could never afford.

[...]

For those less familiar with the Compaq, it has both ISA and EISA slots.

As I understand it, you likely have a Compaq Deskpro 386/25M, which has EISA slots. The earlier "Compaq Deskpro 386/25" seems similar to the "Compaq Deskpro 386/20" I got for free in 1997 (due to "an unfixable problem on the mainboard" which turned out to be a flat Lithium battery for the setup), and is ISA only, with a special slot for the Compaq proprietary 32-bit memory card.

Don't get me started about the quality of the 3600RPM interleave-2 60MB IDE installed in that machine, though. If you needed any kind of performance from the hard drive subsystem, you were better advised to sell your Rolex or your Porsche to pay for the upgrade option for the 130 or 300MB ESDI drives accompanied with a controller that allowed 1:1 interleave.

Disruptor wrote on 2022-09-27, 15:08:

Note that just the Fast-Wide version with the W has the 68 pin connector and delivers up to 20 MB/s.
The Narrow versions you quoted just have the 50 pin connector and is limited to 10 MB/s.

Good catch, thanks for the heads up on this one as I have missed it originally.

By the way, what is the difference between the 2740W and the 2742W?

mkarcher wrote on 2022-09-27, 20:06:

As I understand it, you likely have a Compaq Deskpro 386/25M, which has EISA slots. The earlier "Compaq Deskpro 386/25" seems similar to the "Compaq Deskpro 386/20" I got for free in 1997 (due to "an unfixable problem on the mainboard" which turned out to be a flat Lithium battery for the setup), and is ISA only, with a special slot for the Compaq proprietary 32-bit memory card.

Don't get me started about the quality of the 3600RPM interleave-2 60MB IDE installed in that machine, though. If you needed any kind of performance from the hard drive subsystem, you were better advised to sell your Rolex or your Porsche to pay for the upgrade option for the 130 or 300MB ESDI drives accompanied with a controller that allowed 1:1 interleave.

Indeed, it is a Compaq Deskpro 386/25M. Didn't know that other Deskpro models where ISA only.

Mine originally came with a 60Mb hard drive, but at the time I was not performance conscious, so it seemed amazing 😁
Nowadays, I will be more demanding with my setup and the upgrades...

NightShadowPT wrote on 2022-09-28, 03:53:

Disruptor wrote on 2022-09-27, 15:08:

Note that just the Fast-Wide version with the W has the 68 pin connector and delivers up to 20 MB/s.
The Narrow versions you quoted just have the 50 pin connector and is limited to 10 MB/s.

Good catch, thanks for the heads up on this one as I have missed it originally.

By the way, what is the difference between the 2740W and the 2742W?

The 2740's do not have the floppy controller.