SSL Computer Software - Development Documentation

[marcmozart]

Great stuff - please post it!

The 8" drive was before SASI and SCSI, not sure what protocol.

I also think it should be pretty straightforward to replace the floppy drives by anything that can talk SCSI (ZIP, HDD, whatever) - as long as the PROGRAM device has SCSI ID 1 and the REEL device has SCSI ID 2.
Again, I can only talk about the 3,5" drives - but 5,25" drives are much the same, just a different connector and different size of the floppies. Don't know about the 8" drives though. I once had one but sold it - guess it was SCSI or maybe SASI.

Due to Marc's problems with his drives, I opened up my drive unit just to see what's actually in there.
I also took some pics for documentation and was about to post a little more info on that maybe in the doku thread.

But if that's not needed (or wanted) I will refrain from that.

Cheers,
Matt

[sintech]

As far as I can tell, the 8” type is Shugard SA850, so this would maybe emulate:

http://www.datexdsm.com/emulator/docs/DTX200en.html?gclid=CL-ghoHNh5oCFQ2T3wodEmWzGA

The one problem that springs to mind is the 8” needs a IBM pre-formatted SS SD blank disc, so this format would have to be placed onto the SD card.

[Artur D'Assumpção]

http://youtu.be/yph8BRoa-As

This seems really good. With price of the old drives sky rocketing if this works would be perfect. Also the hassle of managing floppies and their durability would be much much lessened.

[sintech]

I also think it should be pretty straightforward to replace the floppy drives by anything that can talk SCSI (ZIP, HDD, whatever) - as long as the PROGRAM device has SCSI ID 1 and the REEL device has SCSI ID 2.
Again, I can only talk about the 3,5" drives - but 5,25" drives are much the same, just a different connector and different size of the floppies. Don't know about the 8" drives though. I once had one but sold it - guess it was SCSI or maybe SASI.

As far as I’m aware, the TEAC 3.5” drive SCSI is a modified device, so it could sit alongside the 20meg Bernoulli via the same SASI interface.

TEAC, sold a 3.5” with a mass of jumpers, and these could be configured for SSL and AKAI samplers, at some point these were replaced with SMD jumper like resistors

SASI is really SCSI-1?

http://en.wikipedia.org/wiki/SCSI

BTW: I think this is all really exciting stuff.

[sintech]

something like this:

[retrocores]

This document describes the 8" floppy system, I confirmed this while disassembling the boot sector.

http://www.computer-automation-museum.org/ca/pdf/computer-automation/91-53566-00A3--Floppy-Disk_Subsystem_Users_Manual/91-53566-00A3--Floppy-Disk_Subsystem_Users_Manual.pdf

It would be great if we could somehow archive the 8" program disk images?


Steve.

[sintech]

Regarding the TEAC 3.5" floppy with the Jumpers:

Been told that even once the jumpers are set, the drive won't work, until the firmware is flashed.

Apparently, DeskDoctor flashed this firmware onto the off the shelf spare.

[matt]

Ok - this is what can be found inside the G+ Disk Drives Unit :

This is a view inside :



Notice the 2 extra boards in the box ?
These are what I'd call SCSI <-> Floppy mapping controllers

Look at this a little closer :


On these boards, the SCSI ID is set :
For SCSI ID 1 :


For SCSI ID 2 :


Here is some documentation of this :
http://bitsavers.informatik.uni-stuttgart.de/pdf/teac/FC-1/HW_HS_1100.PDF

Btw. - the jumper settings on my drive are the factory preset.


The back says SCSI (sintech - according to your Wiki link SASI is really SCSI-I - didn't know that, thx):


I know these SCSI <-> something controllers when I was playing around with UNIX boxes back in the 90s.
Actually, I still have some for MFM and RLL drives, even for tape drives (don't remember the interface name from memory).

According to all this, I am tempted to think, that a 'standard' floppy could be used instead of the TEAC one (but would have to prove that),

What should be possible is to attach about any kind of SCSI device there when 'just' leaving out the mapping controller

[sintech]

According to all this, I am tempted to think, that a 'standard' floppy could be used instead of the TEAC one (but would have to prove that),

What should be possible is to attach about any kind of SCSI device there when 'just' leaving out the mapping controller

This link gives some info regarding why it's not possible, to plug any kind of SCSI device into the current interface:

http://www.microanalytic.com/products/ssl/01_610.html

[Artur D'Assumpção]

Well if this is a standard SCSI-I interface shouldn't any standard SCSI-I compatible device (in this case floppy) work?

The SCSI controller serves as an abstraction layer between the device and the OS, and the OS should be able to work with it without any specific drivers, only the controller one. When the SCSI-I (II and III) BUS was widely used on servers, I recall that I only had to be worried with the controller drivers. If the drivers we properly developed and had the support, any SCSI drive would work and the OS would interface with it seamlessly.

One could try and buy and old SCSI floppy drive (non SSL) on ebay and try to switch it out and see what happens?

[matt]

This link gives some info regarding why it's not possible, to plug any kind of SCSI device into the current interface:

http://www.microanalytic.com/products/ssl/01_610.html

Ok - I am afraid, the keyword here is 'Bernoulli commands' ...... and such, sintech is right.
This could well be SCSI on the hardware side but the commands used by the SSL computer are not standard SCSI but Bernoulli - which are not known to the usual SCSI device.

[Artur D'Assumpção]

I see what you mean...

http://en.wikipedia.org/wiki/Bernoulli_Box

Maybe the Floppy drives inner-controller needed some type of firmware modifications to be compatible with commands issued via SCSI that were needed by the Bernoulli drive? Some type of SCSI extension that could exist at the time...

The only way to try this theory is to try a standard SCSI floppy drive and see how it goes.     

----

EDIT: At the same time it's really a weird behavior because the Bernoulli drives worked over SCSI, so you shouldn't need to have to modify the other drives to be compatible. Maybe this was a limitation of the OS itself in such a way it was easiest to modify the drive's firmware than the OS?

[Artur D'Assumpção]

One question. The systems that had the Bernoulli drives, had 2 drives, or the Bernoulli was just for the Reel disk?

[sintech]

My system is standard G series.

All systems boot from 8" via the standard CA floppy card.

This new 4100/A has a built in SASI interface that talks to the two
20 meg carts.

Everything is in pairs for backup and transportability

[matt]

EDIT: At the same time it's really a weird behavior because the Bernoulli drives worked over SCSI, so you shouldn't need to have to modify the other drives to be compatible. Maybe this was a limitation of the OS itself in such a way it was easiest to modify the drive's firmware than the OS?

ya - that's something I don't get at the moment.
The 'Bernoulli effect' (as far as I understood it) was more a hardware thing - different kind of handling of the platter(s) in a removable cartridge.

Here's a little more technical background.
http://www.techopedia.com/definition/2155/bernoulli-disk-drive

Maybe I can try a couple of things over the weekend ...... will keep you posted.

Matt