Re: SFD-1001 (8[02]50) diagnostic codes ?

From: Martijn van Buul (
Date: 1998-05-08 11:59:12

Marko Mäkelä wrote:
> On Thu, 7 May 1998, Martijn van Buul wrote:
> > Hmm.... As an off-topic thingy : why rm -fr, why everybody refers to that
> > command as 'rm -rf' ? (gee! There used to be a machine called
> >
> (And there still is a machine  Hmm, isn't it -fr for "fast
> remove"? :-)
Ah well... is now an alias :) 

> > Am I supposed to be glad to know that the zero page of my 1001 is broken
> > (6530? 6504?), knowing that the actual drive mechanism is defective too?
Hmm.. Am I supposed to be glad that there aren't any 6530's or 6504's 
in that SFD-1001? (I got that hint from the PETFAQ, but, then again, that
one handles the 8050) I guess I'll have to dissassemble the ROM to find
out what's wrong.

> Hmm, luckily the RAM is not on-chip on the processor, or is it?
Since it uses 2 6502's, I guess it ain't got any on-chip RAM, indeed 
> > (one of the heads is kaputt. Does anyone having experiencing in adapting
> > PC-HD mechanisms (without Shugart-interface!) to such a device? AFAIK,
> > the 1001 (and 8[02]50) use 80 tracks, DD mechanics. I'm wondering if
> > a 80 tracks _hd_ mechanic would work.)(I guess not)
> I'd also like to fix my 1571's upper head.
Well.. I've given it a thought, and this is what I'm currently wondering:

A HD disk has a higher magnetic permeability, so it needs a stronger 
magnetic field in order to be written correctly. Is this done by changing
the actual head (bigger coil, different core) or just by raising the 
current fed into the head? Since an HD head has a different gap than
a DD drive, I guess the head _will_ be stronger. But then again : Maybe
not for every manufacturer.

PS: an 1571 mechanics can be replaced theoretically with a plain
360 KB PC-floppy if you strip it enough. (it has been done)

Martijn van Buul,
Tijntje@OuterSpace - 3333 

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