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Intertec Superbrain II Jr - system disk
- Thread starter ddp516
- Start date
The Maslin Archive has a few disks in TD0 format. Where are you located?
I think the only superbrain system disk in the Maslin archive is for a QD system (and it's not clear whether it's for the original superbrain or superbrain II). I'm sort of assuming that there is something in the system software image that differs between the three different disk configurations (the user manual also suggests that this is the case). I suspect that the differences are tiny - probably just a table of disk parameters.
I've also found the images on Dave Dunfield's site. But again, I don't see any that are clearly for superbrain-II and the small "Jr" disk configuration. I haven't yet tried these or the image from the Maslin archive, but I will soon.
I'm located in the UK (Bracknell). I don't necessarily need a physical disk - I have a greaseweazle and can write an image to disk.
I've also found the images on Dave Dunfield's site. But again, I don't see any that are clearly for superbrain-II and the small "Jr" disk configuration. I haven't yet tried these or the image from the Maslin archive, but I will soon.
I'm located in the UK (Bracknell). I don't necessarily need a physical disk - I have a greaseweazle and can write an image to disk.
JonB
Veteran Member
The Maslin archive has several images one of which is certainly for a Superbrain II (though it boots up in reverse screen mode). If your machine really is a SB II it might work. If so, it may even read / write a single sided disk, but only so far. The DPB will be configured for a QD drive, so when it tries for side 2 it will error out. It’s not too hard to alter the DPB.
The Superbrain disk format entails reading/writing all of side 1, then working on side 2. It does not treat a 2 sided disk as having cylinders and this is why the basic boot for a QD might work, sort of, on your Junior, but only if the disk is empty enough to not have any side 2 data.
Hmmm, just thinking, if your drive is single density, none of it will be readable. You’d have to try them.
The other thing of note is that the second processor handles disk I/O and its code is on the boot rom. So it would be useful to know what version ROM you have. Either a label on the chip or the sign on message, prior to boot, will tell you. Reason being that if the JR is single density there is probably a difference.
I’m in the UK as well. I’ve designed and written drivers for a simple IDE interface on the Superbrain and I have the ROM in assembler format for the purposes of booting the IDE drive. What I’m saying is I should be able to help you build a boot disk that works on your JR. I’m sure I can get it booting off an IDE drive.
Search YouTube for my channel “JonB Retro” to see the IDE and RTC card in action.
The Superbrain disk format entails reading/writing all of side 1, then working on side 2. It does not treat a 2 sided disk as having cylinders and this is why the basic boot for a QD might work, sort of, on your Junior, but only if the disk is empty enough to not have any side 2 data.
Hmmm, just thinking, if your drive is single density, none of it will be readable. You’d have to try them.
The other thing of note is that the second processor handles disk I/O and its code is on the boot rom. So it would be useful to know what version ROM you have. Either a label on the chip or the sign on message, prior to boot, will tell you. Reason being that if the JR is single density there is probably a difference.
I’m in the UK as well. I’ve designed and written drivers for a simple IDE interface on the Superbrain and I have the ROM in assembler format for the purposes of booting the IDE drive. What I’m saying is I should be able to help you build a boot disk that works on your JR. I’m sure I can get it booting off an IDE drive.
Search YouTube for my channel “JonB Retro” to see the IDE and RTC card in action.
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Thanks, JonB, for your message. Very interesting that it doesn't deal with the disk as cylinders - it had never occurred to me that it would work like this.
The boot ROM says (in the message on the screen) that it's version 4.1
I don't think any of the disk drives used on superbrains are "single density" in the sense of using FM rather than MFM recording.
As I understand it (and I'm happy to be corrected!) the differences were:
Jr (junior) - 35 tracks of 10 512-byte sectors, single sided
QD (quad density) - 35 tracks of 10 512-byte sectors, double sided
SD (super density) - 80 tracks of 10 512-byte sectors, double sided
My machine is definitely a superbrain-II. (TMS2516 [5V only] EPROMS, socket for second character set, battery backed RTC.)
I'm actually a little stuck at the moment - I found I couldn't get the superbrain to turn on - again. I think another of the decoupling electrolytics on the main logic has gone short-circuit, I already had to replace one - I think I'll just replace them all now. But once I get the power back on I'll try those disk images and see what's working.
The boot ROM says (in the message on the screen) that it's version 4.1
I don't think any of the disk drives used on superbrains are "single density" in the sense of using FM rather than MFM recording.
As I understand it (and I'm happy to be corrected!) the differences were:
Jr (junior) - 35 tracks of 10 512-byte sectors, single sided
QD (quad density) - 35 tracks of 10 512-byte sectors, double sided
SD (super density) - 80 tracks of 10 512-byte sectors, double sided
My machine is definitely a superbrain-II. (TMS2516 [5V only] EPROMS, socket for second character set, battery backed RTC.)
I'm actually a little stuck at the moment - I found I couldn't get the superbrain to turn on - again. I think another of the decoupling electrolytics on the main logic has gone short-circuit, I already had to replace one - I think I'll just replace them all now. But once I get the power back on I'll try those disk images and see what's working.
JonB
Veteran Member
Yeah, they are old tantalum caps that look like diodes, next to the DRAM. Not electrolytic.
But check the 12v & 5v rails for a short first.. you never know…
My SB II has the dreaded beeeeeeeeeeeeeeeeeeep of death, gah! But I think SB I is ok. They’re in storage right now after a house move, wrapped in plastic and duct tape with all my other machines. Meanwhile, some guys on another forum are getting itchy for some uIDE boards and I’ve not even established an electronics workshop yet. Too busy decorating and DIYing..
Ok. So you will achieve a boot from at least one of those Maslin images (cannot recall which) but the screen will be reversed. I have a proper SBII boot image somewhere. Want a copy?
But check the 12v & 5v rails for a short first.. you never know…
My SB II has the dreaded beeeeeeeeeeeeeeeeeeep of death, gah! But I think SB I is ok. They’re in storage right now after a house move, wrapped in plastic and duct tape with all my other machines. Meanwhile, some guys on another forum are getting itchy for some uIDE boards and I’ve not even established an electronics workshop yet. Too busy decorating and DIYing..
Ok. So you will achieve a boot from at least one of those Maslin images (cannot recall which) but the screen will be reversed. I have a proper SBII boot image somewhere. Want a copy?
So, things are a lot better now that the tantalum caps aren't shorting out the 12V line.
As you predicted the screen is odd. I just get a white background across the width of any line with text on it, and a solid black cursor.
I can tell that O/S is loaded because if I type `DIR` drive A is accessed and a few more lines (of all-white background) are printed.
If you can find an SBII boot image I'd really appreciate a copy.
JonB
Veteran Member
You have PM... 