zx microdrive on ql for testing the zx drive

[techy]

confusion , as usual so maybe someone here can help me out .

As i am struggeling to get my if1 going ( looks like a dead doornail to me now ) , i need to verify the functionality of the zx microdrive .

Now i have found that a "simple " twist cable sould do .................BUT , i would like a more scientific approach before frying all .

So , what do i need to prepare to hook up a zx microdrive to test its functionality to an ql ??



any help highly appreciated , including help on the if 1 for the spectrum

[Chr$]

So , what do i need to prepare to hook up a zx microdrive to test its functionality to an ql ??

Nothing, just use the ribbon cable that is also used for the ZX Interface to plug the ZX Microdrive into the QL. The ZX Microdrive will face the wrong way (the hole to put them in will face the back) but it should become mdv3_ so test it by dir-ing or format mdv3_

Some ZX Microdrives don't like QL's but in my experience most work.

With regard to the IF1, the thing that is most likely to fail is the ULA chip as they get quite hot. When that is plugged into the Spectrum even without the mdv attached you should be able to tell if it's at least being 'seen' by entering e.g. CAT 1. If it isn't present at all it'll report a bad command or something like that because the CAT command is I believe (someone will correct me if wrong) within the IF1 IF1 ROM. You could also try PRINT PEEK 23729 which should either return 0 for the v1 IF1 ROM or 80 for the v2. Let me just check what that returns of there is no IF1 attached at all....

[Chr$]

Just tried it... if you try to enter CAT 1 on a spectrum that has no IF1, it doesn't accept the line and flashes a '?' before the '1'. Similar thing happens if you try FORMAT "m";1;"name". If those commands are accepted even if the mdv does nothing then you know the IF1 ROM is at least 'present' and connected.

The PRINT PEEK also returns a 0 if there is no IF1 present.

[techy]

Thank you ,

tested ?? i don't want to ruin a ql and zx microdrive in one go

so , dir mdv3_ should make it spin .




re if1 , i tried all possibilities of cat and the peek but no response at all ,
altough i found out that the cat command resides in the spectrum rom with or without if1 connected

will there be some points to test there ??

[NormanDunbar]

If I remember correctly, and if you are interested....

When IF1 is connected to a Spectrum, entering an invalid command caused a paging in of the IF1 ROM, which rechecked the validity of the command. CAT is in the Spectrum ROM but without the mdv parameters, hence it would fail and then work when IF1 kicked in.

Commands had to be present in the Spectrum ROM which is why the IF1 commands just added "invalid" parameters.

Looks like yours isn't kicking in.


Cheers,
Norm.

[Chr$]

Thank you ,

tested ?? i don't want to ruin a ql and zx microdrive in one go

Yes, I've personally used the ZX Microdrive lead to plug in a ZX Microdrive to the mdv expansion port on the right and have accessed it as mdv3_ (and many others have too).

And as Norman says, the CAT command is present but the with the '1' (or 1 up to 8) after it a Spectrum with no IF1 connected won't know what to do with it and it will show the syntax as wrong. Are you sure your Spectrum expansion port connections are clean... a basic thing that you've probably checked but it can be important.

[martyn_hill]

Hi techy

Regarding the IF-1, as well as a defective ULA, it is also quite possible that the Spectrum's z80 CPU is (slightly) defective.

The IF-1, along with certain other Spectrum peripherals rely on a working 'M1' (Machine-cycle-1) signal from the CPU, active during the instruction-fetch cycle.

An unexpanded Spectrum will work quite happily with a faulty M1 line, as will many interfaces (e.g. Kempston Joystick, etc), thus it may go unnoticed until you attach the IF-1.

Thus, it is possible that the IF-1 is working, but to operate correctly, the z80 would need replacing,

If you also have, say, a Multiface-1 or similar, this too requires a working M1 line, and would not work on the Spectrum either and thus would validate whether or not you have a defective z80.

Just a possibility...

[techy]

thanks to all ql is still functional


@ all repliers re mdv ,

mdv3_ is accessible but can not dir or format ...............up to next advice's




@ all repliers re if1 ,

no response from if1 after cat or the peek

ula hasn't burnt out case is without heat damage .

so here also up to next step ............if you can help me