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Forums > CSDb Discussions > C128D - 1571 drive compatibility with demos
2007-04-02 10:26
ready.

Registered: Feb 2003
Posts: 441
C128D - 1571 drive compatibility with demos

Hi,
I just got a commodore 128D, with built in 1571 drive. As far as I read this drive should emulate the 1541 in c64 mode, but... I experienced a few crashes running certain demos. So far Deus Ex Machina and Insomnia both crash right after turning disk side. Risen from Oblivion V2 runs fine in C128 mode.

I thought about a not 100% correct emulation of the 1541 in c64 mode.

Has anybody had the same problem?

thanks,
Ready.
 
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2007-04-12 00:52
raven
Account closed

Registered: Jan 2002
Posts: 137
Insomnia was 100% done on my 128D, including the loader.
The 1571 is the only drive that didnt cause any problems
with the older version of the loader.
It also didnt crash only on the 128D at the partyplace.. heh

The only difference i know of, from tests i've done, are
when using the 2bit+ATN protocol.
On the 1571, two (sometimes one) extra cycles of delay
are needed between serial bus reads on the 64 side.

Other than that, it *should* work the same, in theory
atleast :)


Btw, can you measure the RPM of your drive? there's a tool
that can do that, the name escapes me though..
2007-04-12 07:04
Devia

Registered: Oct 2004
Posts: 401
@ready:
Use 1541-tester for Head Stop alignment: ftp://ftp.zimmers.net/pub/cbm/documents/disk-drives/1541-tester..
..it's option '6' in that prog. (you will need the original calibration disk for that prog to use any of the other options, IIRC)

If you need to do drive alignment, i.e. re-adjust the stepping motor position, you can use various utils.. Personally I have used an oscilloscope and some simple basic proggy for that, but I know there are just as good, if not in fact better options to adjust without a scope.
Check out ftp://ftp.zimmers.net/pub/cbm/documents/disk-drives/ ..there're some text files in there, that might explain some things.

Basically you have to know what you're doing ;-)
The head stop align-thingie in that first prog will explain what to do for that particular job. You won't need any disks.
For alignment of the stepping motor you will however need a "known good" disk. I.e. a disk formatted and written in a drive you'd consider to have a "reference" calibration.
The actual calibration is FRUSTRATING, to say the least.. everything is connected to everything and nothing is calibrated once you tighten all the screws again or flip over the drive so it's no longer upside down.. Bottom line: It requires some experience to do it properly ;)

..but you should be able to align the head stop using that first prog though.. it's not that difficult.


2007-04-12 10:32
ready.

Registered: Feb 2003
Posts: 441
Thank you very much Devia!! I'll give it a try as soon as I have some time. I agree with you, it's always better to know what I'm doing, that's why I'd like to learn how it works before putting my hands on it.

I'll let you know how it goes.

Cheers,
Ready.
2007-12-21 12:28
ready.

Registered: Feb 2003
Posts: 441
Finally I had my C-128D drive fixed. It was easier than I though: the problem was that the metal rail on which the drive heads run on was sticky and dirty. Pulled it out, cleaned it with alcohol and now Insomnia works great!! Even if the drive cannot pass the drive test in the Insomnia demo engine.

Now I have also a 1571 external drive. It was for the US market, so on bottom it says Power 117V AC 60Hz. Here in Italy we have 220V 50Hz. Some electrical equipment don't care between the 2 standards and work regardless 50Hz or 60Hz. But how does the 1571 cope with this? Has anybody ever tried?

thank you,
Ready.
2007-12-21 12:42
Devia

Registered: Oct 2004
Posts: 401
Haven't got a 1571 by me right now, but since the so called "Universal Power Supplies" capable of handling 110-240V @ 50-60Hz didn't get common until recent years, my bet is that you will fry the thing trying to supply it with 230V. - unless they buildt in a 110/230V manual switch like you see on most AT/ATX power supplies.
2007-12-21 15:57
null
Account closed

Registered: Jun 2006
Posts: 645
or get an inverter/converter/adapter/whatever

------------------------------------
http://zomgwtfbbq.info
2007-12-22 01:06
Style

Registered: Jun 2004
Posts: 498
Ready: thanks for that, I have a 1571 here that I think suffers the same issue you described - Ill pull it apart and clean/regrease the rail and see what happens.
2007-12-22 01:55
Style

Registered: Jun 2004
Posts: 498
Actually, how do you align a drive with an oscilloscope graham?

I have one right here.

Im guessing, with a suitable alignment disk, you could measure the output of the read head and tune?

2007-12-22 03:29
Graham
Account closed

Registered: Dec 2002
Posts: 990
Best would be to use a program in the drive which bumps the head to track 1 and then simply reads the disk + prints track number on screen all the time.

Then use your oscilloscope to get a maximum signal of track 1.
2007-12-22 05:18
Style

Registered: Jun 2004
Posts: 498
Ill look into it - I wouldnt mind restoring this 1571 back to new condition.
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