30 Oct
2001
30 Oct
'01
5:47 p.m.
I'm referring to the registered prom in the disk controller when I made that
remark, since I'm not sure that the boot code had to be modified at all between
the two sector sizes, though it's possible.
It's not pilot error that causes the Apple disk subsystem to fall apart whenever
there's the slightest error, it's the "we've got your money now, so
we've got
you by the short and curly" attitude that Apple has always had with respet to
their customers' data. That design of WOZ's was clever and cheap, ... REALLY
cheap ... , but not terribly reliable. Back in the early '80's I didn't know
a
single user of the genuine Apple disk subsystem that didn't have a data loss per
hour in steady use. The guy I mentioned initially had phone-order business,
and, because his environment was not perfectly clean, he was constantly having
to reboot his Apple, since it couldn't recover from a disk read error, and this
was before he had a toll-free number. His customers didn't like the extra 10
minutes it took to get the job done. Remember, that was back when long distance
cost something and a dollar was a DOLLAR, not just the price of a candy bar.
After he was switched to the CP/M system, he went over a year without a data
loss, even though he had power outages now and again, and the risk of
contamination was just as bad for the CP/M system as for the Apple. I can't
explain it all, but as I said, he happily chucked the Apple after all the grief
he'd had. That, by the way is exactly what I plan to do with my remaining Apple
hardware once I get this current APEX software thing outta here. My recent
contact with the Apple][+, IIe, //c, etc, has convinced me that there's no point
in perpetuating the myth.
I remember how people whined about the PC's <abort, retry, fail> error message
for disk errors, yet Apple didn't even have one. It just went TILT.
Even back in those days we'd all come to expect better than that, and, by the
way, the whole problem was exxentially gone if one used 8" FDD's with the SVA
controller.
Dick
----- Original Message -----
From: "Sellam Ismail" <foo(a)siconic.com>
To: <classiccmp(a)classiccmp.org>
Sent: Tuesday, October 30, 2001 9:35 PM
Subject: Re: hard-sector 5 1/4 disk
On Tue, 30 Oct 2001, Richard Erlacher wrote:
I have to disagree, actually, because the Apple
diskettes all seem to
have the holes, not that it matters. While the drive may not have the
Only because that's how they were manufactured. It would be silly to
order disks without the index holes at what most likely would have been a
much higher price just because you didn't need it.
Which, admittedly, I don't understand, since
the PROM they used was
rather small. (...that's where the firmware lives, doncha know...)
Most of the work was in the software, actually, since it had to do
what the disk format required, and figure out along the way which one
it was.
The PROM only had the boot code in it (less than 256 bytes...some of the
tightest code EVER!) It was responsible for loading the first sector of
the first track into memory and then executing that code. It could be
actually be used to read any numbre of sectors from the track the head was
currently positioned over. With the addition of maybe 32 more bytes of
6502 code, you could write a head positioner routine that could move the
head around and read any sector from the disk.
I've never liked Apple-disk-related problems,
since the Apple system
was incredibly fragile and highly unreliable. The first Apple client
Huh?
I had who had been using an Apple][+ in his
business summarily took
his ][+, drives, and monitor, the whole shebang, out to his dumpster
the day I moved his database to a CP/M system with a conventional FDC
and a conventional pair of 8" DSDD drives. I'd say he was in hog
heaven. His business picked up (though I don't know that the switch
had anything to do with that) and his monthly expenditure for MAALOX,
Whiskey, and prune juice was substantially reduced. Moreover, he got
to see a lot more of his wife and kids.
Sounds like user error to me. RTFM.
Until a few weeks back when I got into retrieving
old 6502 source
files, I had forgotten what a piece of crap that disk subsystem was.
Huh?
No wondern so many folks switched to 8"
drives. I surely wish I could
find an old SVA controller ... <sigh> It's a real wonder
microcomputers caught on as well as they did, given the standard set
by the Apple ][. The work WOZ did to create the disk subsystem was
really ingenious, but still orders of magnitude less reliable than
what was offered on more conventional systems.
I have hundreds (>~500) Apple ][ disks that are still readable to this
day. Of my 17 or so years of hacking Apple ][s, I've only lost a handful
of disks, and that was usually due to physical errors. Once or twice I
lost a disk because random sectors were overwritten whilst hacking and the
system jumped into the middle of a DOS call, but that was rare.
Anyway, I'll just take your statement for what it is.
Sellam Ismail Vintage Computer Festival
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