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Question about older IBM computers

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barney

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I know that the older IBM computers (286/386/486) used a special arcitecture (MCA I believe). I just had a question as to what type of hard drive they used? Is it a typical 50 pin scsi? Does it use a typical IDE hard drive?

Barney
 
It depends on the model... MCA is used on some 386 and 486, all the 286 are ISA.
The PS/2 Model 80 for example has a MCA hard disk controller card, SCSI or ESDI.
The PS/2 Model 55SX uses another type of hard disk connected directly to the MCA bus.
Some ISA models (PS/1 2011, PS/2 30-286, etc) use a proprietary hard disk, non standard.
Other ISA models (PS/1 2121, PS/1 2133) use IDE drives
 
Some PS/2 model 25 systems came with the traditional ST-506 interface, but most other PS/2 models used ESDI, which is an improved interface based on the ST-506. However, all drives used in the PS/2 systems uses a proprietary connector only used by IBM.
 
per said:
Some PS/2 model 25 systems came with the traditional ST-506 interface
Click to expand...

Hate to do this, but citation please? I've been trying to hammer down this piece of information for longer than I've had any PS/2, actually...

Unless you mean shipped with an add-in card; that would make sense. But AFAIK that mobo HDD interface is the same as found in the 30 and submodels, and is more than just a unique connector.
 
kishy said:
Hate to do this, but citation please? I've been trying to hammer down this piece of information for longer than I've had any PS/2, actually...

Unless you mean shipped with an add-in card; that would make sense. But AFAIK that mobo HDD interface is the same as found in the 30 and submodels, and is more than just a unique connector.
Click to expand...

This site http://mastodonpc.tripod.com/ibm/type.html contins info about which models are SCSI or not, but separating between the ST-506 and ESDI is a little more difficult.

I based my original point on the initial version of the Wikipedia PS/2 model-table, which may well have been incorrect.
 
I'm specifically referring to the Model 25 (and 30, and submodels of each, as all of these 'appear' to use the same proprietary interface).
 
First an understanding that PS/2 models below 50 are ISA, 50 and above are microchannel. Drive types vary as widely as the systems that used them. I'll try to come up with the stock drives for you, although that can be changed:

Model 25: None, proprietary 20 or 30MB drive, or 20Mb MFM for add-on adapter
Model 25 286: Proprietary 30Mb drive
Model 25SX: IDE, typically 40 or 80Mb
Model 30: None or proprietary 20Mb drive
Model 30 286: Proprietary 30Mb drive
Model 33: Laptop IDE
Model 35SX: IDE
Model 40SX: IDE
Model L40SX: Laptop IDE
Model 50: Proprietary MFM drive
Model 50Z: DBA ESDI
Model N51SX/N51SLC: Laptop ESDI
Model 53SLC2: IDE
Model 55SX: DBA ESDI
Model 56SX/56SLC/56SLC2/56SLC3: SCSI
Model 57SX/57SLC/57SLC2/57SLC3: SCSI
Model CL57SX: Laptop DBA ESDI
Model 60: Conventional 5-1/4" MFM or ESDI drive
Model 65SX: SCSI drive
Model 70: DBA ESDI
Model P70: DBA ESDI
Model P75: SCSI
Model 76: SCSI or IDE
Model 77: SCSI or IDE
Model 80: Conventional 5-1/4" MFM or ESDI drive
Model 85: SCSI
Model 90: SCSI
Model 95: SCSI
 
Thanks IBMMuseum, definitely cleared up what I'd been wondering about. Hopefully OP's concerns also?

Though, re: Model 50 - proprietary MFM - MFM can mean a few things (kind of like IDE, and RLL, etc). Is that just a proprietary re-connectorization of the 'ST-412' type interface, or indeed something different, similar to how the 25 and 30 use their own special unique thing?
 
kishy said:
Though, re: Model 50 - proprietary MFM - MFM can mean a few things (kind of like IDE, and RLL, etc). Is that just a proprietary re-connectorization of the 'ST-412' type interface, or indeed something different, similar to how the 25 and 30 use their own special unique thing?
Click to expand...

The hard drive in the model 50 is based on the WD-325, a standard ST-412 drive but shrunk to fit in 3.5" bays. The WD-325N combines power and both ST-412 cable attachments into a single 50(?) pin mounting that plugs straight into the Model 50's controller card. Twas a very strange system. (Well, that's if I remember it correctly. I lack a Model 50 to double check.)

See http://ps-2.kev009.com:8081/ohlandl/8550/8550_Controllers.html for partial confirmation of my memory.
 
Last edited:
Yes, that's about correct for the Model 50. I know, I had to track down a WD-325 to replace the missing one in the 50 I got from somewhere. I think I needed a sled too and got one of those and a whole box of Model 90 parts as a bonus.
 
Well, hey, I don't need the thing. I obtained it thinking it was the drive for the 30/25 proprietary interface, only to find the connector is longer.

So I set my mind on hopefully selling it (in its untested, unknown state - best to assume broken) for an amount that would enable me to get the proper drive, but I since gave up on that venture since there's really no point in pursuing a failure-prone drive of such tiny capacity when I have other arrangements working and don't care even the slightest bit about authenticity.

So if someone is looking for the 325N...perhaps get in touch...I coulda swore I made a for sale thread for it, maybe not, I dunno. The biggest problem with these drives and selling them seems to be that someone who is looking for one doesn't know what the thing is called, since they are lacking one to begin with.
 
Druid6900 said:
Well, it you want it tested, ship it to me and I'll stick it in the Model 50 and see what it does.
Click to expand...

I appreciate the offer, but at $10 shipping (give or take, this is about the cheapest in-country parcel price) each way, I'd have to sell it for more than I consider fair ($20-30ish) to compensate for the costs of getting it tested...I dunno, if you would be interested in buying it once tested, or brokering a sale or something, please PM me and we can figure it out there.
 
So what model did the WDL-320 go into? I have one of those also in an unknown state (and no PS/2 machines to test it in)?
 
The PS/2 model 30-286 has a WDL-320 drive, (20 mb, proprietary interface)
 
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