Woolie Wool wrote on 2020-07-16, 14:29:

I am looking to finally start putting to use all the parts I've collected for a VS440FX/Pentium Pro build, but one thing I'm still missing is storage. The Adaptec AHA-2940UW PCI card looks cheap and plentiful on eBay, and I was wondering if people here have experience using them and if they're suitable for a 1996-97 era DOS/Win9x system. Does it have a BIOS extension so it can boot from SCSI? Will it be any faster than IDE?

I actually had that card in my Compaq PC back in 1997-99, so I'd say it's suitable. Perhaps I've had the 2940AU version, but they're very similar, 2940UW supports wide SCSI in addition for a bit of extra speed. Make sure to get one with its own SCSI BIOS so you can boot from it. Adaptec has drivers for DOS and most older versions of Windows, as well as various UNIX flavours. It will be faster than IDE of that period, especially if you pair it with a 10 or 15K hard drive (but beware, those are noisy). SCSI always had an advantage over old Parallel IDE in that it could offload the disk activity overhead from the host CPU and also use DMA bus mastering by default. System felt more responsive as a result.

to be fair though, while this aspect of SCSI is always mentioned, adaptec's own threadmark shows major improvements in reducing CPU load under windows with 430FX and later chipsets+IDE DMA activated, with period drives. 2.18mb/s and 35.61% CPU load with DMA off vs. 2.51mb/s and 17.97% CPU load with DMA on (430FX, p133, 95 osr2, quantum fireball 1280at), if anyone is curious about numbers. and under DOS, in practice being limited to 16-bit access seems like a bigger bottleneck than IDE PIO anyway.

the ability to circumvent drive size limits via SCSI ROM in conjunction with built-in driver support in period OSes is probably a bigger deal nowadays.

my 440FX board has PCI bus mastering IDE built in...

For slot1 and later definitely, and likely for socket 7/super socket 7 aswell, using a bus-mastering PCI SATA controller or even a decent IDE one with an IDE to SATA adapter makes the most sense, IMHO (like a Promise or Silicon Image SIL3114) :

a) drive size issue are gone with LBA48 support
b) current SATA mechanical drives are usable
c) current SATA SSDs are usable
d) throughput can reach 90MB/second (maybe not socket 7, but still)
e) no need to hunt down old, potentially unreliable, noisy and slower parallel SCSI drives (compared to modern high platter density SATA drives or SATA SSDs) .
f) faster and cheaper than a 20MB/sec max SCSI2SD v6 at 98 USD just for the SCSI2SD itself .

What I use and would recommend is a 2,5" PATA IDE SSD from Yansen, they come in smaller sizes starting with 8 GB and going up from there. I mounted it with a 2,5 > 3,5 converter caddy inside the PC and use a 44-pin to 40-pin IDE adapter, from which the standard IDE cable then plugs into the motherboard controller. Supports bus master DMA, is fast, completely silent, reliable and consumes hardly any power. This works great on my 440BX slot-1 motherboard with a P-III CPU. Compatibility is excellent and I even installed picky period operating systems like OPENSTEP on the SSD.

I still keep a 2940AU SCSI card in the PC for my Iomega Jaz drive, but I don't use SCSI for fixed disks any more.

darry wrote on 2020-07-17, 02:59:

For slot1 and later definitely, and likely for socket 7/super socket 7 aswell, using a bus-mastering PCI SATA controller or even […]
Show full quote

For slot1 and later definitely, and likely for socket 7/super socket 7 aswell, using a bus-mastering PCI SATA controller or even a decent IDE one with an IDE to SATA adapter makes the most sense, IMHO (like a Promise or Silicon Image SIL3114) :

a) drive size issue are gone with LBA48 support
b) current SATA mechanical drives are usable
c) current SATA SSDs are usable
d) throughput can reach 90MB/second (maybe not socket 7, but still)
e) no need to hunt down old, potentially unreliable, noisy and slower parallel SCSI drives (compared to modern high platter density SATA drives or SATA SSDs) .
f) faster and cheaper than a 20MB/sec max SCSI2SD v6 at 98 USD just for the SCSI2SD itself .

I already knew a SATA card would be more practical, and have one in my KT7A Athlon XP machine driving three cheap WD hard drives, and it is indeed economical, practical, and almost zero fuss. But the Pentium Pro is to be something of a gimmick build, with a conceit that it was a Windows NT workstation built in 1996 and converted into a DOS/Windows 95 gaming rig. SCSI is part of the gimmick, and so is whatever frustration I encounter getting it working.

Woolie Wool wrote on 2020-07-17, 14:44:

darry wrote on 2020-07-17, 02:59:

For slot1 and later definitely, and likely for socket 7/super socket 7 aswell, using a bus-mastering PCI SATA controller or even […]
Show full quote

For slot1 and later definitely, and likely for socket 7/super socket 7 aswell, using a bus-mastering PCI SATA controller or even a decent IDE one with an IDE to SATA adapter makes the most sense, IMHO (like a Promise or Silicon Image SIL3114) :

a) drive size issue are gone with LBA48 support
b) current SATA mechanical drives are usable
c) current SATA SSDs are usable
d) throughput can reach 90MB/second (maybe not socket 7, but still)
e) no need to hunt down old, potentially unreliable, noisy and slower parallel SCSI drives (compared to modern high platter density SATA drives or SATA SSDs) .
f) faster and cheaper than a 20MB/sec max SCSI2SD v6 at 98 USD just for the SCSI2SD itself .

I already knew a SATA card would be more practical, and have one in my KT7A Athlon XP machine driving three cheap WD hard drives, and it is indeed economical, practical, and almost zero fuss. But the Pentium Pro is to be something of a gimmick build, with a conceit that it was a Windows NT workstation built in 1996 and converted into a DOS/Windows 95 gaming rig. SCSI is part of the gimmick, and so is whatever frustration I encounter getting it working.

Thank you for explaining . In that case, a 40MB/second AHA-2940UW ( https://adaptec.com/en-us/support/scsi/2940/aha-2940uw/ ) seems quite appropriate .

2940uw is a great card

Woolie Wool wrote on 2020-07-17, 14:44:

darry wrote on 2020-07-17, 02:59:

For slot1 and later definitely, and likely for socket 7/super socket 7 aswell, using a bus-mastering PCI SATA controller or even […]
Show full quote

For slot1 and later definitely, and likely for socket 7/super socket 7 aswell, using a bus-mastering PCI SATA controller or even a decent IDE one with an IDE to SATA adapter makes the most sense, IMHO (like a Promise or Silicon Image SIL3114) :

a) drive size issue are gone with LBA48 support
b) current SATA mechanical drives are usable
c) current SATA SSDs are usable
d) throughput can reach 90MB/second (maybe not socket 7, but still)
e) no need to hunt down old, potentially unreliable, noisy and slower parallel SCSI drives (compared to modern high platter density SATA drives or SATA SSDs) .
f) faster and cheaper than a 20MB/sec max SCSI2SD v6 at 98 USD just for the SCSI2SD itself .

I already knew a SATA card would be more practical, and have one in my KT7A Athlon XP machine driving three cheap WD hard drives, and it is indeed economical, practical, and almost zero fuss. But the Pentium Pro is to be something of a gimmick build, with a conceit that it was a Windows NT workstation built in 1996 and converted into a DOS/Windows 95 gaming rig. SCSI is part of the gimmick, and so is whatever frustration I encounter getting it working.

Go for it ! Please post some pics when done. I always like seeing a good mid 90's SCSI machine running well !

The answer to your question is; YES.

If you have never dealt with scsi, it has its pros and cons. I cannot recommend it for the uninitiated. I know others have said it, but I want to backup their statements with a pci sata card.

That said, I love to see scsi builds.

luckybob wrote on 2020-07-18, 04:16:

The answer to your question is; YES.

If you have never dealt with scsi, it has its pros and cons. I cannot recommend it for the uninitiated. I know others have said it, but I want to backup their statements with a pci sata card.

That said, I love to see scsi builds.

I have built a retro system before (KT7A/AMD Athlon with both the built-in IDE and PCI SATA across four hard drives, a CD-ROM, and two floppy drives), and I've built three modern systems, so this is not my first rodeo. I've done the more practical options, now I want to get ambitious and go crazy with all the workstation parts I dreamed of but couldn't have as a kid with a 486 in the '90s (and this will probably still be easier than a 486). So far I'm planning on:

* Chernbro SR20503 ATX case (already have)
* Intel VS440FX PCI/ISA motherboard (already have)
* Intel Pentium Pro @ 180 MHz, 256KB cache (may upgrade to a blacktop 200 with 1MB cache)
* 64MB 60ns EDO RAM (already have)
* Matrox Millennium MGA 2064W video card (already have)
* Voodoo 1 3D accelerator (planned)
* Adaptec AHA-2940UW SCSI controller (purchased)
* Seagate 4GB 68-pin SCSI hard drive (purchased)
* Gateway Wearnes 8x IDE CD-ROM drive (already have)
* TEAC FD-235HF 3.5" floppy drive (already have)
* TEAC FD-55GR 5.25" floppy drive (planned)
* IDE LS-120 floppy drive (planned)
* Terratec EWS64L/XL/XXL sound card (cries in poor)

Likely when the SCSI parts come in I'll build what I have and add the rest later. I think I have an ESS ES1868F around somewhere as a stopgap sound solution. I've thought of buying more SCSI hard drives and just filling the whole case with stuff, but I've heard adding more drives/drive letters taxes conventional memory.

The old scsi drives are just terrible noisy...

Dominus wrote on 2020-07-19, 06:20:

The old scsi drives are just terrible noisy...

Any well-worn drive that does not use fluid bearings is nightmare fuel for me . The faster it spins, the worse the noise (higher pitch) . Using a newer (and thus likely quieter) LVD drive (up to Ultra-320) on an older single-ended SCSI controller is an option (using passive adapters) if one wants to do SCSI for the sake of doing SCSI .

7200rpm SCSI drives have a pleasant access sound IMO. But 10K is in the annoying territory, at least the one I've used.

My Compaq Proliant 800 (an entry level dual PPro server) came with 2x Seagate ST34371W (4.3GB) drives. One of them had more bearing noise than the other, and both have since gone bad, but I liked them when they worked.
I don't remember what controller that machine used, but I remember AHA-2940 series cards being very popular in the late 90s, at least on P2-P3 systems (not sure if it was around yet for the PPro).

Forsa wrote on 2020-07-16, 22:50:

Make sure to get one with its own SCSI BIOS so you can boot from it. Adaptec has drivers for DOS and most older versions of Windows, as well as various UNIX flavours.

Did the 2940uw come out with a bios? All the ones I'm seeing available have a empty spot where the bios should be and the only image I see on google with the spot populated is on the 2940uw pro. Is that right?

I mainly want the 2940uw to use a macsd on PC. So does that mean without the bios I cant boot off a virtual cd with it?

The DIL32 socket was only used / populated, when the chip was supposed to be replacable by the end user without soldering. Per default the BIOS is stored in the (square) flash-ROM that´s located right of the DIL socket.
So all 2940UW without a DIL socket do have their own SCSI BIOS. You can verify this when you look at the traces on the backside:

I don't know, so I will comment 😀
Maybe 2940U2W (80MB/s) will be better choice ?
I remember that even AHA-29160 (64bit PCI) works just fine in 32bit slot (however AFAIR it was later machine - P4 or Core2 based, I'm not sure about Pentium Pro).

I have AHA-2940AU (not UW) in my Windows 95C machine (PCChips M573). It is connected to a 18 GB SCSI hard drive (MAE3182LC) via a SCA8050 adaptor. Works well.

The only problem is that the case drive activity LED (connected to the SCA8050) works the opposite of expected: ON when drive is inactive, and OFF when active. IDK how to fix this.

majestyk wrote on 2022-07-31, 08:24:

The DIL32 socket was only used / populated, when the chip was supposed to be replacable by the end user without soldering. Per default the BIOS is stored in the (square) flash-ROM that´s located right of the DIL socket.
So all 2940UW without a DIL socket do have their own SCSI BIOS. You can verify this when you look at the traces on the backside:

2940W2940UW.jpg

Thanks I did indeed confuse the dil socket for the bios socket. Thats great to hear that is not the case because the 2940UW is a lot easier to find for me.