VDrive ZX or QL?

A place to discuss general QL issues.
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Ruptor
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VDrive ZX or QL?

Postby Ruptor » Wed May 20, 2020 2:54 pm

I have looked around but I can't answer my question of can l use a VDriveZX on a QL? I don't care about file or format differences between the computers it is just that at the moment I am attempting to fix my QL and would like a VDrive on it but if I can't fix it then could the VDrive be used on my spectrum 48K?


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Chr$
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Re: VDrive ZX or QL?

Postby Chr$ » Wed May 20, 2020 3:56 pm

No, you can't. I once asked Charles about this (just in case) and it's not possible, the ZX and QL versions are too different. Mr Ingley's words: "the embedded toolkits are written for two different host processors".


Collector of original and some newer QL related computers, accessories and software even though I don't understand how any of them work.
Original BBQL's: 3x German, 1x UK model (plus quite a bit of other old stuff)
Custom AT cased QL system with Gold Card, Qimi mouse, Hermes and MFM HDD
PC with QXLII card installed
Q68 also present

Ask me about near NOS re-felted good quality Microdrive Carts - many available.
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Re: VDrive ZX or QL?

Postby Ruptor » Wed May 20, 2020 4:18 pm

Thanks. The ZX microdrives work on the QL according to this thread so it isn't hardware stopping it.
viewtopic.php?f=2&t=1899
I don't know how VDrives are constructed but if the software can be replaced they could be made to work maybe I think. Not desirable for the person selling them to make them compatible since it could halve the market.


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Re: VDrive ZX or QL?

Postby Chr$ » Wed May 20, 2020 4:37 pm

Yes, the actual original ZX MD's work usually, I've used one on my QL.

I suppose in theory it may be possible, but the fact the toolkits are 'embedded' would suggest that they cannot be changed, apart from perhaps by Charles. The vDrive QL/ZX PCB's are also physically different (the ZX version allows you to plug it on to the left of the computer and the QL version to the right without any upside-down twisty cableness).

Buy one of each, he's a top bloke and has been very helpful to me with my silly support queries - that were not always directly in relation to the things he sold me in the first place!


Collector of original and some newer QL related computers, accessories and software even though I don't understand how any of them work.
Original BBQL's: 3x German, 1x UK model (plus quite a bit of other old stuff)
Custom AT cased QL system with Gold Card, Qimi mouse, Hermes and MFM HDD
PC with QXLII card installed
Q68 also present

Ask me about near NOS re-felted good quality Microdrive Carts - many available.
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Ruptor
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Re: VDrive ZX or QL?

Postby Ruptor » Wed May 20, 2020 5:14 pm

Thanks. Maybe when all this Covid crap is over and post actually works. :roll:


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Re: VDrive ZX or QL?

Postby XorA » Wed May 20, 2020 11:29 pm

Erm, you can as long as you have at least one VDrive QL then the VDrive ZX will daisy chain off that.


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Re: VDrive ZX or QL?

Postby Ruptor » Thu May 21, 2020 11:09 am

Is it possible to pull a microdrive from my dead QL and use it on my Spectrum ZX? Is it just the physical connection problem or some fundamental interface problem?


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Re: VDrive ZX or QL?

Postby martyn_hill » Thu May 21, 2020 12:21 pm

Hi Ruptor

The pin-out from the MDV headboard to the baseboard differs between QL and ZX MDV units (the baseboard being part of the QL mainboard, but separate inside the ZX MDV units), so you would need to add a physical adapter to accept the QL pinout and match it to the ZX baseboard. Doable...

There is also the problem of the different approach adopted by each platform for managing the WP line - the QL isn't actually able to read the status of the WP line directly, but instead has wired the WP switch in such a (clever) way as to both inhibit the ERASE current and force the ULA to Read mode when the WP is activated (i.e. when the WP tab is missing - better to call it a Write Enable tab...) Thus the QL will fail a write/Format operation only once it fails to read-back/verify what it has just attempted to write.

In the Interface-1 instead, the ULA reads the WP switch and the software returns immediately with a 'Read-only' error if any write access/Format is attempted on an WP'd cartridge.

Physically (aside from the different head-board layouts), they appear to match one-another.

Electrically, there is no real difference either - the QL units having some minor passive component changes to improve performance - and the file-format that is read/written to the actual cartridge is handled by whichever software/OS is driving the MDV. The ULA used (2G007E) is also the same - although the very last QL' MDV's manufactured (and the equivalent OPD units) were fitted with the 2G007E5 - no idea how these two differ - they appear to be interchangeable.

All in all, unless you were really stuck for other options, I wouldn't bother trying to re-purpose a QL MDV unit for the Spectrum/Int-1, but with care, it could be done...


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Re: VDrive ZX or QL?

Postby martyn_hill » Thu May 21, 2020 12:30 pm

Hi again...

Coming back to your original question - the main reason why Charles' two units are not interchangeable is likely because the micro-controller code has to differ in order to interpret the diverse file-system formats that are effectively embedded in the (same) electrical signals that appear on the MDV bus, before writing to or reading back from the SD Card.


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Re: VDrive ZX or QL?

Postby Ruptor » Thu May 21, 2020 4:12 pm

Hi Martyn
martyn_hill wrote:All in all, unless you were really stuck for other options, I wouldn't bother trying to re-purpose a QL MDV unit for the Spectrum/Int-1, but with care, it could be done...
Thanks for the info. At the moment I have two working MDVs in a dead QL & a Spectrum 48K with no easy method of saving files that it badly needs. If I fix the QL an MDV will get removed anyway for an SD card slot so it would be an ideal swap out. Anyway I thought everybody here was in to tinkering and I am joining in. :lol:



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