CST THOR 20 2F

[Jeff$]

Hello,

New member here, can't really class myself as a QL collector, but owned a Thor for 30+ years, used it in the early 90's then stored it away in a cupboard. I powered it up maybe 20 years ago and it had issues with the keyboard so I stored it again and forgot about it. I would periodically look on line for THOR information, and the only info beyond BIO stuff all lead to this forum.

So finally this month I had a sudden urge to unpack the Thor and take another look, spurred on by the mentions of Varta battery leakage, I confess my THOR still has the original battery, which had not leaked after 35 years... or if it had no damage was caused (have now removed and waiting for new one to install on separate daughter board). This may be due to it being stored in dry areas not subject to wide temperature changes, and storing the THOR on its side with the battery at the bottom (deliberately as I realised the battery may have been an issue all those years ago).

Thor 20 daughter board

Thor 20 internals

I did some technical reading on the THOR looking to work out the issue with my THOR, the symptoms were it would reach the post screen and then nothing, keyboard was dead, or sometimes allow you to press F1/F2 and then type 3-10 characters on the keyboard before locking up again. My keyboard has one faulty key, the switch is broken, so I thought the issue would be the keyboard, perhaps the ZX8302 communications controller or even the serial keyboard interface Motorola MC 6850. Sadly I'm not setup for testing other than perhaps swapping out chips (not healthy on a old PC I know as voltage levels etc may not be stable). But then reading the THOR technical notes from Dilwyn's superb resource, it mentions that disk read/write operations share the I/O with the keyboard and will interrupt and even completely stop keyboard input. This got me thinking and disconnecting my two floppy drives, got the keyboard working...... just sharing this advice for fellow THOR owners that its sometimes an easy solution rather than the chips.

I checked the drives and found one to be faulty, it seemed to think it had a disk inserted even when it didn't, so was over riding the keyboard input. The drives are NEC's FD1036A, with the copper shielding etc I bet they don't make them like that anymore. Thankfully the other drive works other than when doing a disk ejection it gets stuck.

So now my THOR boots and runs, so the next issue is 35 year old floppy disks, I still had original system disks etc, and some do read, but its a bit hit and miss and I realise I need to get these imaged somehow. I've bought a Gotek drive as that seems the way to go, so if anyone has any advice on using one with a THOR/QL, how do I generate a disk image etc.... sector by sector copies ?.

Thor Post Screen

I still have the original 3 button mouse (made in England, I doubt we still make mice), and booting up ICE, it still works and was a walk down retro memory lane.

Thor mouse

Thor ICE

I booted a few programs, some failed and a few ran (or partially ran), so I guess its a case of salvage what I can and hopefully see if images exist on the NET. The fact any disks worked after 30+ years was a surprise.



As a side note, I have an external micro drive unit (has the voltage regulator removed to work on a THOR), that back in the day I recall using with the THOR, I had to remove the THOR 20 board, replace it with 68008 processor (68020 was too fast to allow the micro drive to function correctly), change the system roms from 5.22 to 4.22, alter a few jumper settings (I recall at least one for the floppy drives that needed removing). So yes you could use a micro drive on a THOR 8. But I'll not be trying that now with 35 year old roms etc.

I hope my post helps keep a little bit of the History of the THOR 20 alive.

[Jeff$]

A few screen shots as it doesn't seem to allow me to post more than 5 photos in a single post.

Thor System Disk Boot screen

Thor Spellbound

Thor Spanish ? Demo screen

[Chr$]

Fabulous looking machine/project. *jealous*

[vanpeebles]

Thats amazing, looks great

[Dave]

The batteries start leaking because of a chemical process. When discharged, the contents expand compared to new state. Containing a paste with a liquid electrolyte, the electrolyte is the only thing that can move and is forced out.

Even if you see no signs of leakage, there can still be some electrolyte sitting there in very small quantities... waiting... watching....

Just clean around the area with some IPA and then some plain water on a cotton ear bud.

[Derek_Stewart]

Hi,

I used to know someone in the North East of UK, who had a Thor 20, looked great.

I found an Thor 1 at a Radio Rally, which I thought wonderful a QL with SCSI hard drives.

But when I looked the internal of the Thor 1, I was unimpressed with the quality of the expansion board. In fact the only think good was the case, but not in black.

The same with the other expansions at that time looks primitive compared to the Miracle products.

I still have the the Thor 1 case, ram expansion board and floppy drives, the rest failed.

[Jeff$]

The batteries start leaking because of a chemical process. When discharged, the contents expand compared to new state. Containing a paste with a liquid electrolyte, the electrolyte is the only thing that can move and is forced out.

Even if you see no signs of leakage, there can still be some electrolyte sitting there in very small quantities... waiting... watching....

Just clean around the area with some IPA and then some plain water on a cotton ear bud.

Dave you got me worried, and although a pain I took the boards apart again and gave around the battery a good clean. Hopefully safe now.

[Derek_Stewart]

Hi,

I had 2 Thor 1 cpmputers both batteries leaked and damaged the PCB.

The battery should have a date code on the outside of the battery body.

I would advise changing the battery.

[Jeff$]

Don't worry it was removed in my first post. I'm waiting on a daughter board to mount it away from the main pcb.
I checked the old battery, no date code, just "Varta Mempac 3.6v 100mA" and stamped "Made in England" on the base, are they still made in the UK ?.
It doesn't seem to have bulged, and no apparent corrosion on it, so hopefully it hadn't leaked, but pcb cleaned anyway, so hopefully all good.

If I can't recover the Thor System disks are any available on line?

Call it memory fade, its been 30years, but I recall you had to manually load the rom toolkit extensions at startup or do it in the boot file. Can anyone remind me please?
Also could you relabel a floppy drive to be a Mdv so the older software runs as Mdv1, I vaguely remember you had to jump through hoops to run many things including reducing the memory.

The manuals are just as bad as they were back in the day

[Jeff$]

Managed to find some of the old manuals, so answered my own questions. TTK and TK2 for the roms. So happy that DIR now scroll locks, was driving me potty