2 Oct
2007
2 Oct
'07
5:23 a.m.
Hi,
Unfortunately, this is normal behaviour for a lot of disk system faults.
I've just worked my way through a huge pile of Apple II disk drives and
controllers. Many of the drives and some of the controllers showed the fault
described here - head stepped all the way out looking for data on track
zero, finding nothing. #1 cause here was dirty heads, followed by bad
alignment, then various analog board faults. Slight alignment issues or
slightly dirty heads would cause a violent-sounding reseek.
I will have to spend some time eventually going through the faulty drives
and figure out what's wrong. I have an oscilloscope (10Mhz only, but I have
a feeling that'll do!), and the analog boards don't look overly complicated.
Does anyone know of a reference that details signals at test points etc?
Knowing what I'm looking for would be nice. Does anyone have an image or
similar for a test disk that can be written with a known-good drive? As
mentioned in a recent post, any disk without copy protection would do if
not.
I developed a very rough but surprisingly functional test for bad alignment;
putting a little pressure on the head carrier (or spiral disk) to move it a
tiny amount in each direction was often enough to bring track zero close
enough to alignment that the drive would spring into life. If that worked,
at least I knew that the drive was basically functional, and probably just
needed an align. I also need to track down info on how to align those
spiral-disk-head-drive type mechanisms (Shugart? or were they ALPS? I
forget). I used to know this stuff once, but that was a long time ago, and
it's just not coming back on its own.
Mike.
----- Original Message -----
From: "Jules Richardson" <julesrichardsonuk at yahoo.co.uk>
To: <General at 5star.net.nz>; "Discussion at 5star.net.nz:On-Topic and
Off-Topic
Posts" <cctalk at classiccmp.org>
Sent: Tuesday, October 02, 2007 11:59 PM
Subject: Apple ][ (clone) disk booting
Morning,
What's the normal procedure to boot a floppy from an Apple ][? I'm just
taking a look at my Mitac [1] clone (with a view to selling it) and got
curious as to whether it'd boot a standard Apple DOS system disk.
If powered up with a drive connected the spindle motor starts and it'll
step the drive head back to track 0 - but nothing more.
On the one hand, it's entirely possible that the machine isn't a close
enough clone to work with standard Apple DOS (that wouldn't surprise me at
all, in fact) - but on the other, maybe I'm just missing some standard key
combination to magically boot from the drive... (whilst I've got an Apple
///, I've never used an Apple ][ in my life)
I can hit CTRL-reset and the machine will drop to BASIC; is there a normal
way of booting (or at least bringing up a dir) a floppy from BASIC on a
genuine ][?
[1] Quite an impressive machine. Has some flavour of far-east legends on
the key fronts, as well as regular ASCII (we had a discussion about it on
here once, but there were conflicting opinions on what language it
actually was). Built-in disk controller, joystick port, tape, TV
modulator, 80-column card. There's a little backplane which can be plugged
into the machine's expansion port and gives you five Apple ][ card slots,
too.
cheers
Jules