Theoretically it should be possible to (with correct adapters/terminators) connect an U320 drive onto a SCSI-1 adapter.

In practice, older adapters have various limits. I encountered an 8GB size limit on early AHA-2940 BIOS versions myself. AHA-1540 is much older than that. So you might have issues with newer drives.

That said, if you want optimal performance, a CF to IDE adapter with decent (industrial) CF card will do a lot better.

Agree that is it possible but not practical. There is a 8Gb limit up to the 2940 series and no ISA card known can handle above 8gb AFAIK.
Also being DOS/WIn3.x (no way you are running W9x on a 386 with good success 🤣) so limited to 2Gb partitions so at best you could have 4 x 2Gb anyway.....since DOS has an 8GB limit.
Disk Drive Overlays work with motherboard based BIOS but not SCSI adapter based....

I mean the "8GB limit" only applies to the capacity you can use. There is nothing stopping you using the first 8GB of a 140GB drive if you want to!

Marco wrote on 2023-01-07, 00:09:

Dear all, […]
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Dear all,

Is it possible to use more modern SCSI drives with above Adaptec ISA SCSI 2 50pin bus card (via active 80/68 to 50pin adapter)?

Why do I want that:
- newer drives are cheaper then real 50pin ones
- higher chance to get a non noisy drive
- newer drives are faster - with ISA bus at least seek time wise

I’m using a 386sx. I’m just tuning around and trying to get most out of it. SCSI in particular due to the cpu offloading.

PS: so far I found some diffuse hints that using the external scsi port could lead to most compatibility with new drives.

Thanks a lot

I have a similar system.
386sx 20 MHz
20 MB RAM (4 as EMS)
Adaptec 1542 B with a 1 GB narrow SCSI HDD
SoundBlaster 16 ASP
Tseng Labs ET4000 W32 ISA graphics card
Since I don't have a busmaster network card, I still use 3COM 3c509 card.
Well, this system even runs Windows 95 B. But it still lacks of performance since it is a 386sx.
Windows sounds are converted to ADPCM, and use hardware acceleration of the ASP chip on the SB16 (44 kHz, 4 bit ADPCM).
Windows 95 Plus! Pack installed to enable drag full window movement with acceleration of the ET4000 W32.
Busmaster SCSI transfer.

Yes, I can even burn CDs with up to double speed, but I don't waste my PlexWriter on this computer.
Yes, it can even handle U320 drives. But the BIOS is limited to use up to 8 GB of a drive.

dionb wrote on 2023-01-07, 00:25:

In practice, older adapters have various limits. I encountered an 8GB size limit on early AHA-2940 BIOS versions myself. AHA-1540 is much older than that. So you might have issues with newer drives.

It depends on what kind of the 1540 you have. The latest bios for the 1540CF / 1542CF supports the INT13 extensions to overcome the 8GB barrier, but the latest BIOS for the 1540B / 1542B doesn't. It's likely that the 1540CP / 1542CP also received an update with INT13 extensions. If you run an operating system that doesn't use the BIOS (like Linux after booting), the 8GB barrier doesn't affect you at all. The main point that the target OS of many retro enthusiasts, i.e. DOS, doesn't support drives exceeding 8GB still stands, though.

Thanks a lot guys. Thus U320 should work. That’s great and 8gb are enough since most stuff is connected via smb share.
And yes also win95 running. Quite ok. Quite… 😀 but yes you might wonder how kind of ok it runs with good gdi acceleration, ram and good hdd.

Thanks will therefor look for a u320 drive. Any recommendations for an Adapter are welcome.

Good weekend

Ps. Thanks also for the 1540CP hint! Will look for it. Important that I can change address awash from 330 port

Oh, you will need a SE capable terminator for your wide cable too.
At the time of U160 and U320 drives the termination was no longer a matter of the drive.

So I will need:

- Adaptec 1540/2CF
- u320 SCSI Drive
- active Adapter 50->68pin (with termination?)
- the mentioned Se terminator. (Like this: https://www.electromyne.de/Cables---Adapters- … -Connector.html)?
- …

Did i miss(understand) anything?

BR

depending on which cable you use, 50p vs 68p, you'll need slightly different adapters.

with a 68p cable, you'll likely need a 68p terminator for the other end of the cable, since most of those cables tend to have one terminator at the end of the cable. If it hasn't then you'll need two terminators
and you'll need a 68p-50p adapter so you can hook the cable to your scsi card.

with a 50p cable, you'll likely need a 68p-50p adapter with high side termination, and a terminator for the 50p cable, since you can use the scsi card itself as the other end of the cable and most of the time it has termination built in, or it can be supplied by adding some resistor arrays.
https://github.com/pdaderko/16702B/tree/main/ … I_50_to_68_male 68p-50p male with high side termination

edit: the 68p-50p adapter might not be required to have the high side termination. it depends on the harddrive. Using the AEC-7726 adapter, so one can use IDE drives on scsi, requires it.

Thanks a lot. I will try to make a shopping card out of it. Hopefully I’ll manage it

Take care guys

Dear all,

I have to admit I give up. I couldnt identify the real necessary components on my own.

What I found:

SCSI Adapter 80to50pin:
https://www.ebay.de/itm/151277101212

50pin scsi cable:

https://www.ebay.de/itm/364099766084

I suppose this isn’t enough. What else do I need exactly (termination, …)

I known it might be impolite but could you maybe post some links to buyable articles as eg on eBay?

I really dint fully understand what I need to Connect my aha 1542cp to my 80pin SCSI drive (to be bought set)

Is there something more simplier when going from 68pin down to 50? Maybe like this cable:

https://www.ebay.de/itm/273955077130

Sorry for asking again. Thanks a lot

1 - Do you plan on adding other devices to the scsi chain and if yes, which ones ?

2 - Also, which hard drives are you currently planning to use on the scsi adapter? ( brand/model# )

3 - Also, aside from the scsi adapter, is there any scsi device/cable/... that you already own ? (I'm guessing no)

edit :

adding descriptions and partial links
/itm/333152058296 : Foxconn Ultra 160/320 SCSI 68-Pin Female Terminator for Internal SCSI Cable $10
(This one you add to the end of the cable that doesn't have a terminator)
/itm/224397627174 : PTC Internal SCSI Adapter, HPDB68 (Half Pitch DB68) Female to IDC 50 Female $13
(this one you plug into the scsi card)
/itm/270834414605 : 36inch HPDB68 Internal SCSI-3 68-Pin 4 Drive Ribbon Cable w/ Terminator, FS-104T $40

Now depending on which scsi hard drive you buy, if SCA 80p you'll need this
/itm/394357191556 : SCSI SCA 80Pin to 68Pin to 50Pin IDE Hard Disk Adapter Converter Card Board #JD $10

and if you want to add another cdrom, or harddrive or zip drive or ... a 50p one, you'll need another 'HPDB68 (Half Pitch DB68) Female to IDC 50 Female' for that device.

Thank you very much. Before going into detail analysis and seeing the prices (in Germany often even higher) just go for a zuluscsi solution could be even the better solution as it can be connected directly to SCSI-2 hba‘s isn’t it?

weedeewee wrote on 2023-01-15, 21:09:

1 - Do you plan on adding other devices to the scsi chain and if yes, which ones ? No I will just add a hdd. […]
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1 - Do you plan on adding other devices to the scsi chain and if yes, which ones ?
No I will just add a hdd.

2 - Also, which hard drives are you currently planning to use on the scsi adapter? ( brand/model# )
I am open. Currently would go for this:
36 GB Fujitsu SCSI Server Festplatte mit 80-pol. Anschluss
Model: MAJ3364MC, Part-Nr.: CA05668-B53500SP,
S26361-H554-V100 oder andere

3 - Also, aside from the scsi adapter, is there any scsi device/cable/... that you already own ? (I'm guessing no)
nope 😀

Oh, you need a SCA connector/adapter too then.

(Narrow-)SCSI -> 50 connectors
Wide-SCSI -> 68 connectors
SCA (Wide-SCSI + power + IDselector + LED) -> 80 connectors

Marco wrote on 2023-01-15, 21:53:

Thank you very much. Before going into detail analysis and seeing the prices (in Germany often even higher) just go for a zuluscsi solution could be even the better solution as it can be connected directly to SCSI-2 hba‘s isn’t it?

Yes, with a 50p cable with only 2 connectors.

I didn't know that one yet. thanks.

as for the prices, I forgot about the shipping costs, customs, ...
although those parts should also be available on the german market from a local seller.
Ask around, maybe someone still has all those parts laying around.

Disruptor wrote on 2023-01-16, 00:37:

Oh, you need a SCA connector/adapter too then. […]
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Oh, you need a SCA connector/adapter too then.

(Narrow-)SCSI -> 50 connectors
Wide-SCSI -> 68 connectors
SCA (Wide-SCSI + power + IDselector + LED) -> 80 connectors

That was listed 😉
/itm/394357191556 : SCSI SCA 80Pin to 68Pin to 50Pin IDE Hard Disk Adapter Converter Card Board #JD $10

Re: Gateway 2000 overdrive build

I got 135gb of scsi working on win 95 on my 486 class build

I just want to provide feedback:

Bought / took into operations
1. Adaptec AHA 1542CP
2. SCSI 50Pin 1-to-1 Cable
3. SCSI 50Pin to SCSI 68Pin Adapter
4. IBM DGHS 9,1GB SCSI 68Pin with internal termination

Results:
- System works but mentions "there are more then 2 terminators..." which I cant understand
- Average Throuput wont pass 1,8MB/s which is a joke for me espc. when running on 12Mhz ISA/DMA Speed.

I will have to check last points in details. Comments are welcome

Thanks so far for your help for taking above setup into ops.

If there is a termination fault, the SCSI system may fallback to async mode. 3,3 MB/s max.
Perhaps your DGHS has the termination enabled too (as well as the controller and on the end of the 68 pin cable). Please fix it.