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SMD disk drive testing

D

dluck

Experienced Member
Joined
Feb 9, 2015
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114
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Campbell, CA
I have several SMD and what I think are SMD drivers that I'd like to test.
Of these are 5.25" seagate ST41201J and PA4A2A.
I have some with correct power supply. Powering those up I get a blinking green light as I hear it spin up. Then I hear it exercise the arm and green lights goes solid green,.
Some of the drives are without power supplies but plugging those into this same power supply so far gets the same power up behavior. I'd like to test these a bit more.
I have access to several vintage computers of which I've not powered up or tried to resuscitate in awhile, except for my Amiga computers. Unfortunatly the only disk drive controllers I have for the Amigas are scsi and ata/ide. I tried looking for an SMD to scsi or ATA but couldn't find anything available. Maybe there is something in the warehouse I've not discovered yet.
I do have a sun3/50 and a sun 3/60, not yet power up. Also some microvaxes, some decmates, apples, trs80s, cbm, Ti's, HPs.
I've not investigated all those other machines to see if they have an SMD controller. I should check out the PDL 11/44 I have. But I'm trying to avoid restoring the more ancient hardware at this time to just test and exercise some SMD drives,
Eventually I plan to sell some of these SMD drives and because of the weight and shipping costs it would be better if I can test them first to avoid shipping a boat anchor.
Suggestions?
 

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What does SMD stand for? Seagate Magnetic Drive? Search-engine comes up with Surface-Mount Device, which I'm sure is incorrect here.
How many pins are those headers? Looks like as many, or more, than SCSI! Doesn't appear to match MFM style connections either.
Sorry for not contributing anything helpful, it's just the first I've ever seen or heard of this interface.
 
dluck said:
I have several SMD and what I think are SMD drivers that I'd like to test.
Of these are 5.25" seagate ST41201J and PA4A2A.
I have some with correct power supply. Powering those up I get a blinking green light as I hear it spin up. Then I hear it exercise the arm and green lights goes solid green,.
Some of the drives are without power supplies but plugging those into this same power supply so far gets the same power up behavior. I'd like to test these a bit more.
I have access to several vintage computers of which I've not powered up or tried to resuscitate in awhile, except for my Amiga computers. Unfortunatly the only disk drive controllers I have for the Amigas are scsi and ata/ide. I tried looking for an SMD to scsi or ATA but couldn't find anything available. Maybe there is something in the warehouse I've not discovered yet.
I do have a sun3/50 and a sun 3/60, not yet power up. Also some microvaxes, some decmates, apples, trs80s, cbm, Ti's, HPs.
I've not investigated all those other machines to see if they have an SMD controller. I should check out the PDL 11/44 I have. But I'm trying to avoid restoring the more ancient hardware at this time to just test and exercise some SMD drives,
Eventually I plan to sell some of these SMD drives and because of the weight and shipping costs it would be better if I can test them first to avoid shipping a boat anchor.
Suggestions?
Click to expand...
Correction: "several SMD drivers" should be "several SMD drives"
 
Your MicroVAX and your PDP-11/44 could be equipped with SMD controllers that would work with those drives. I still use 14", 10", and 8" SMD drives with DEC and Sun machines.
 
I'll look to see what controllers might be installed. Maybe this is nieve but does the SMD spec support a geometry query? The tester that I borrowed only has preprogrammed drive specs for older drives. And it doesn't seem to allow me to edit them. I'm able to get the tester to do some basic tests. One of which is the seek test. When putting it in random mode, I can hear the drive do a lot of seeking as the cylinder number changes, and it does this without reporting any errors. Does the DEC or Sun software use hard coded drive specs (geometries) or do they query the device so that I wouldn't need to change the software to try running these drives if they didn't originally support them.
 
Thanks for the link to the spec. There are no commands to query geometry. It appears that a controller can get cylinder count by setting cylinder address and seeing if it reports error. It can get sector count by counting pulses between index pulses. Head selection though doesn't seem to have a bounds check for error in the definition. The data clock is probably also not discernable and needs to match. The drive generates read clock and the controller generates write clock.
 
This is from memory when I did some research into SMD disks a number of years back.

The original SMD by CDC was hard sector. A fixed divisor of the servo clock which were set up using dip switches on the drive. BTW the servo clock is always present and is used by the controller to generate the write clock.

Then as SMD evolved and other players joined the game there were soft sector drives where the controller decided the format of the track.

For a hard sector drive it should be possible to just read the dip-switches to get numbers of sectors. A SMD disk has a certain data rate. The original CDC had slightly below 10MHz. Later on there were up to 24 MHz as far as I remember.

This means that the controller need to be able to keep up with the data rate. Not all controllers were designed for the higher rates.

The unformatted capacity per track can be calculated from the data rate divided by rotational speed which should be possible to find in data sheet.

The ESDI interface is very similar to SMD but instead of bus and tag type of interface for commands and status there is a serial bus. You save quite a lot of signals going to serial.

There are SCSI to SMD bridges. Adaptec AHA-5580 is one. Probably hard to find now.
 
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