Denial

Anyone who has owned a 1541 disk drive knows about the loud rattling or banging noise the drive makes when it is unable to read the disk. The drive moves the head to the extreme outer edge of the disk and forces it repeatedly against an end-stop, causing the banging noise. If this is allowed to happen repeatedly, the drive head will be put out of alignment.

The 1541 bangs its drive head when formatting disks, too. This means that even if all your disks are in good shape and you don't use old copy-protected software (which is also known to cause head-banging), your drive can still be put out of alignment thru normal use.

My question is, are there any models of Commodore disk drive that don't bang the drive head when formatting a disk?

The only other Commodore disk drives I have used are the 8250 and 2031 drives with the PET/CBM. Both of them bang the drive head when formatting, if I recall correctly. The 8250, in particular, makes a very loud and disconcerting banging noise.

But what about the 1571 or 1581? I've heard that the 1571 has a track zero detector, which would presumably mean it doesn't need to bang the drive head when formatting. What about the 1581?

Commodore Explorer wrote:My question is, are there any models of Commodore disk drive that don't bang the drive head when formatting a disk?

The 1541C.

If you use openCBM, I believe you can use a command to not knock the head while formatting disks!

I have heard that the 1571 is a great drive because it doesn't bang the head (although I've never owned one).

I do have a 1541-II and can confirm it bangs the head - although it seems a little less harsh that a 1541.

Apparently, there were little leaf springs you could buy and put into your drive instead of the hard metal stop. Therefore, headbanging wouldn't mis-align your drive. I may have some sort of instructions on this somewhere, otherwise, does anyone have any info?

All this because they were too cheap to put a Track 0 sensor in it....

Sigh.

channelmaniac wrote:All this because they were too cheap to put a Track 0 sensor in it....

Sigh.

Every penny mattered in those days. The fact that we even had a disk drive based computer at the prices we could buy them at was remarkable.

Yeah, but Commodore could've taken a page out of Apple's book.

They made a set of floppy drives that were controlled by software rather than hardware. Their Disk II drives and the later DuoDisk drives were works of art! A couple of PROMs, a few bits of TTL logic, and some analog devices were turned into a masterpiece of simplicity. A cheap and RELIABLE disk drive.

It was also a VERY profitable drive for Apple.

The 1541 drive could've been done much cheaper and more reliably.

channelmaniac wrote:The 1541 drive could've been done much cheaper and more reliably.

Commodore's reasons for creating an intelligent disk drive are fairly well documented. I could try to find a few articles on the subject if you're curious as to what those reasons were. Discussing whether they made the right or wrong decisions seems pointless at this point especially since hindsight is always 20/20.

If you have the URL it'll save me from having to find it. I'd like to see their reasons.

It's not about saving CPU cycles as that bit banger serial port they implemented doesn't allow for that.

gklinger wrote:

channelmaniac wrote:The 1541 drive could've been done much cheaper and more reliably.

Commodore's reasons for creating an intelligent disk drive are fairly well documented. I could try to find a few articles on the subject if you're curious as to what those reasons were. Discussing whether they made the right or wrong decisions seems pointless at this point especially since hindsight is always 20/20.

Even in hindsight, I think the move toward intelligent disk drives was the right one. I still would rather have seen a move toward intelligent hardware in general for all computers. I am rather saddened about everything being software-driven these days...."optimised for Windows", yeah, sure.

A cool thing about the 1541 is that it can be interfaced to pretty much anything without lots of driver code. Just high level syntax for load, save, sending commands to the drive.. It is known to have been used both with synthesizers and home brewn Z80 systems.

I found this article on C= Hacking

Aligning 1541 Drives
by Ward Shrake (taken from comp.sys.cbm)

A discussion regarding Commodore 1541 disk drive alignment procedures, with suggestions.


http://www.ffd2.com/fridge/chacking/c=hacking9.txt

It dosn't really tell of any drives that don't knock, but It does say how to fix the problem on the 1541, and keep it fixed!

I was browsing C= Hacking and came across that article and remembered reading your post Commodore Explorer, hope that helps!

If they don't have a track 0 sensor then they knock. It's Commodore's way of finding track 0. Take 40 steps backwards. If you hit the wall, keep stepping until you count 40. Then you KNOW you are at 0.

Apple did the same thing but instead of using a stepper motor with a metal belt they used a plastic disk on their early drives. The head assembly rode in a groove on the disk and when it ground against zero then the pin rode across the top of the disk and back into the groove.

Later when they went to the same style of head moving assembly as Commodore - the stepper motor with the metal belt - then they started having alignment issues too.

RJ

Wow! Thanks for all your responses. Sorry I haven't responded sooner; I've been very busy this past week.

Royas wrote:If you use openCBM, I believe you can use a command to not knock the head while formatting disks!

Thanks for pointing that out -- I downloaded the source code to openCBM and took a look at it; it looks interesting. It does indeed have an option to format disks without banging the drive head, but I'm skeptical as to whether that would actually work on a 1541 or 1541-II.

Here's why: The formatting routine in the 1541's ROM starts at track 1 and formats each track until it reaches track 35. But if it is formatting a disk, how can it know where track 1 is? The only way for it to know at which track its head is positioned is to read the disk at that point. Since the disk is assumed to be blank, the only thing it can do move the head blindly toward the outer edge of the disk. (Channelmaniac summed this up nicely.)

Because of this, I believe head-banging when formatting a disk is inevitable on the 1541 and 1541-II. I remember typing in a "turbo-format" program from a late-1980s issue of Compute's Gazette which claimed that, in addition to formatting a disk much more quickly, it could do it without banging the drive head. The first claim turned out to be true -- it formatted a disk in about 15 seconds instead of 90, but I am quite certain I heard a head bang at the start -- a very fast one, because it seemed to move the drive head much more quickly than normal (GEOS and some fast loaders could move the drive head more quickly, too).

Because the trouble involves the initial positioning of the head at track 1, it would, in theory, be possible to write a non-head-banging disk formatting program by first having the user insert a "known good" disk (a disk in good condition that was formatted by a well-aligned drive), seeking to track 1 on that disk, then having the user remove it and insert the disk to be formatted. If I'm able to learn more about the 1541's internals, I'd love to write such a program.

I have 1571's and 1581's ( a few of each) and none of these models exhibit the knocking issue. Apparently it was fixed with the 1571 model, and I do not think there was ever an issue of this type with the 1581's as far as I ever heard.

All of my 1541's will knock when running some software with odd protection schemes, and NEVER run those "make music with your drive" type programs of course