• Please review our updated Terms and Rules here

MFM controller for S-100

RickNel

Veteran Member
Joined
Apr 24, 2009
Messages
640
Location
Canberra, Australia
A lot of threads on MFM hard drives seems to end with people saying how crap they are and throwing them out.
In the spirit of this forum, I'm hoping to save one just for the heck of it.
It's an NEC-D3142, 42Mb. On power on, it spins up and seems to seek track 0. It came with an ISA-bus controller card from a Wang 80386 PC, but the card doesn't work in a standard PC ISA slot as far as I can determine in any AT mobo I have - possibly BIOS are all too new.
I have an S-100 system (IMS 5000) that I'm working on. The BIOS can be configured for MFM HDD.
If MFM drives have a reputation for failing, it stands to reason there should be some controller cards around that have no functioning disks to run on them.
Any ideas on where such s-100 MFM controller a card might be found (other than dumpsters)?
Did all MFM controllers have the same 34pin+20pin dual cable connections with the same pinouts?
Also, any source for documentation on the NEC-D3142. It seems to have been a pretty common drive in its time?
Any help or advice appreciated
 

patscc

Veteran Member
Joined
Apr 13, 2005
Messages
2,311
Location
Stevens Point, Wisconsin
drives

drives

Well, first here's the man page for the drive:
http://support.necam.com/oem/HDD/D3142.asp

MFM gets a bit of a bad rep by folks coming of IDE & ATA spec stuff, which is pretty much plug and play. MFM drive types were often closely bound to the controller cards.
If you change your mind back to ISA, there's probably a controller out there.

Probably not the earliest ones, but If you can dig up a Cromemco STDC card. that should work with your drive.

patscc
 

MikeS

Veteran Member
Joined
Dec 23, 2005
Messages
7,506
Location
Toronto ON Canada
Did someone say Cromemco? Yes, I do have one or two STDC's but not cheap...

Now if you wanted a WDI or WDI-II then we could definitely talk, but although they're MFM they're probably not what you're looking for. In answer to your other question, although MFM is commonly used to describe a hard disk using the ST412/506 34&20 pin interface, technically it only refers to the recording method and not the computer interface.

The IMI interface that the WDI's use is an example; the later 5 1/4" IMI drives could be bought either way, the same HDA and analogue board with either an IMI (single 34-pin cable) or ST506 interface board, for use with either a WDI or STDC respectively. As a matter of fact an upgrade kit was available consisting of an ST-506 interface board and the matching STDC controller.
 

RickNel

Veteran Member
Joined
Apr 24, 2009
Messages
640
Location
Canberra, Australia
to patssc - thanks for the specs link and other info

to MikeS - In this case, how does "not cheap" translate into $$?
I haven't seen anything pop up on ebay in the few weeks since I've been interested.
 

QuantumII

Veteran Member
Joined
Aug 12, 2008
Messages
503
Location
Oslo,Norway
I gutted a large CPM system yesterday, and inside I found a 8" floppy drive and a MFM HDD connected to a daugtherboard which in turn connected to a standard 8" floppy drive port on the controller.

I wonder what it's for ? Maybe it uses the HDD to create logical drives or something?
 

MikeS

Veteran Member
Joined
Dec 23, 2005
Messages
7,506
Location
Toronto ON Canada
to patssc - thanks for the specs link and other info

to MikeS - In this case, how does "not cheap" translate into $$?
I haven't seen anything pop up on ebay in the few weeks since I've been interested.
Yeah, S-100 HD controllers are pretty thin on the ground; I wonder how hard it would be to make an S-100<>ISA bridge board... Andrew, are you reading this? ;-)

I'd say around $150 for an STDC, but frankly, unless you need one for a Cromemco I wouldn't recommend it. It's a fairly intelligent controller with a Z80 coprocessor, DMA controller, 64K RAM, 8K ROM etc. that reads and buffers an entire track at a time, so I'd think a driver or BIOS would be a bit of a challenge even if you did want to pay my exorbitant price... ;-)

m
 

Chuck(G)

25k Member
Joined
Jan 11, 2007
Messages
40,241
Location
Pacific Northwest, USA
Outside of the Compupro Disk 3, I don't think I've ever run across an S100 ST506-interface controller. Even the Disk3 is very late in S100 history (~1984).

What's more common are SASI interface boards for S100 (little more than a parallel port) that connect to something like an outboard WD1001 controller hooking up to an 8" SA1000-type drive.
 

MikeS

Veteran Member
Joined
Dec 23, 2005
Messages
7,506
Location
Toronto ON Canada
Outside of the Compupro Disk 3, I don't think I've ever run across an S100 ST506-interface controller. Even the Disk3 is very late in S100 history (~1984).

What's more common are SASI interface boards for S100 (little more than a parallel port) that connect to something like an outboard WD1001 controller hooking up to an 8" SA1000-type drive.
Well, Vector Graphic had at least one, basically a floppy controller with a few extra bits added to connect to a "real" ST-506.

Guess we've come full circle with IDE putting most of the smarts back onto the drive ;-)
 

QuantumII

Veteran Member
Joined
Aug 12, 2008
Messages
503
Location
Oslo,Norway
Sounds intriguing all right; what's the make & model of the CP/M box and the drive?

It was in a Tandberg TDV 2324 (Norwegian brand) CPM machine. I rescued the MFM HDD; the controller and the 8" floppy drive.

The HDD is a Rodime Series 200 , and the floppy drive is a Shugart.
 

Chuck(G)

25k Member
Joined
Jan 11, 2007
Messages
40,241
Location
Pacific Northwest, USA
Here's that card I mentioned... Seems to be MFM-to-SASI (Shugart) controller

Xebec controller

Yup, just like the WD1000/1001--insanely easy to imterface to. The WD controllers used the Signetics 8x300-series bipolar controllers. You can probably still find the WD controllers within the TRS-80 community.

My first IBM 5150 hard disk was a Shugart SA1004 and a WD1001, hooked to a homemade interface card in the PC.
 

Chuck(G)

25k Member
Joined
Jan 11, 2007
Messages
40,241
Location
Pacific Northwest, USA
Ah yes; I've got the SCSI version of the Xebec MFM bridge. Never figured out what to do with it though.

I've got a couple of OMTI RLL-to-SCSI cards somewhere. They're identified as having the "Mac SCSI" ROMs. At one time, MFM/RLL drives were cheap in comparison to SCSI drives. I think this sort of bridge card was useful as a money-saver. I used mine (wtih some external "glue" logic) to interface an Atari ST to an MFM hard drive.

Well, there's your "S100 MFM controller". SCSI isn't much more than a couple of parallel ports and software following a protocol definition, so it should be pretty straightforward to interface one of the SCSI-MFM bridge boards to an S100 parallel card.
 

RickNel

Veteran Member
Joined
Apr 24, 2009
Messages
640
Location
Canberra, Australia
HDD as virtual FDDs

HDD as virtual FDDs

My IMS International system docs (1981) refer to an optional "hard disk sub-system" with removable cartridges in optional capacities of 32mB, 64mB and 96mB, in each case presented to CP/M as multiple "diskette drives" of 8mB capacity. No hardware or vendor standard is mentioned, but maybe that configuration suggests a Shugart-style controller (SASI)?

Does anyone have information/memories on that style of HDD sub-system?

The IMS system's FDC is Shugart-compatible card driving two Tandon 5.25 FDDs.

The FDC card does not have any connectors or headers other than the two 34pin FDD connectors, so I guess the HDD subsystem was driven from its own s-100 card, not from a daughter-board like the interesting XEBEC shown by MikeS.

So some kind of s-100 card must have been out there from around 1980 to as long as these machines were still running.

My puzzle is still - how to connect a NEC D3142 to a S-100 system.
 

QuantumII

Veteran Member
Joined
Aug 12, 2008
Messages
503
Location
Oslo,Norway
Yesterday I got the cover off my TeleVideo machine, and inside it had a similar adapter for connecting the HDD. Floppy connector (A flat one, you plug the floppy-end of the cable into it) in one end, and MFM hdd connectors in the other end.

Maybe they're quite common after all..

The TeleVideo is a multi-user Z-80 machine, but not S-100
 

QuantumII

Veteran Member
Joined
Aug 12, 2008
Messages
503
Location
Oslo,Norway
Hey, an update on the MFM S-100 controller.

I have here the Cromemco STDC, which is a S-100 bus ST-506 controller :)

This is exactly what you are looking for right ?

The link to the manual is here

It was in a pile of other misc cards I got from my haul.
 

RickNel

Veteran Member
Joined
Apr 24, 2009
Messages
640
Location
Canberra, Australia
Cromemco STDC

Cromemco STDC

The control and data cable connectors match the NEC D3142, but its hard to see how this card could run between CP/M and the NEC HDD. Unless Cromemco had a CP/M implementation for it with a different manual.

Even so, that Interrupt Priority Cable looks scary - is that a feature of Cromix-based systems or Cromemco generally? Not compatible with my system as far as I can see... Interrupts are all handled through the bus and system I/O card. This manual seems customized for a particular HDD with no other options.

Would there be workarounds?
 
Top