donw@zehntel (Don White) (12/21/88)
Can anyone at Commodore tell us why (in detail) the drives click? I know
they are looking for disk insertion, but HOW are they doing it and why?
Don't all drives have some kind of hardware to tell you if a drive is
loaded? Couldn't drives be kept at one known location (like track 0)
where you KNOW there should be SOME information? ANd just do reads with
no more head positioning?
?????
Don White
zehntel!donw
Box 271177 Concord CA. 94527-1177jesup@cbmvax.UUCP (Randell Jesup) (12/22/88)
In article <742@zehntel.UUCP> donw@zehntel (Don White) writes: > > Can anyone at Commodore tell us why (in detail) the drives click? I know > they are looking for disk insertion, but HOW are they doing it and why? > Don't all drives have some kind of hardware to tell you if a drive is > loaded? Couldn't drives be kept at one known location (like track 0) > where you KNOW there should be SOME information? ANd just do reads with > no more head positioning? Last time, so listen carefully: :-) Drives only tell you if a disk has been inserted when you step the head. Stepping the head is much faster than reading a track. SOME (not all) drives won't try to step below track 0, but latch the diskchange line anyway. This is how noklickstart works, if you have the right drives. Other drives bang the heads against the stop, making evil noises and perhaps hurting your drive. -- Randell Jesup, Commodore Engineering {uunet|rutgers|allegra}!cbmvax!jesup
davidg@killer.DALLAS.TX.US (David Guntner) (12/22/88)
From article <742@zehntel.UUCP>, by donw@zehntel (Don White): > > Can anyone at Commodore tell us why (in detail) the drives click? I know > they are looking for disk insertion, but HOW are they doing it and why? > Don't all drives have some kind of hardware to tell you if a drive is > loaded? Couldn't drives be kept at one known location (like track 0) > where you KNOW there should be SOME information? ANd just do reads with > no more head positioning? From what I understand, what AmigaDOS is doing is moving the head of the drive from track 0 to track 1 (and then back again). This changes a status bit if a disk is present, and AmigaDOS (or is it a KickStart function?) then knows that a disk has been inserted. There are a few programs that stop the clicking by making the head move from track 0 to track -1. Since there ISN'T a track -1, nothing moves/clicks, but that status bit still gets updated.... --Dave -- David Guntner UUCP: {ames, mit-eddie}!killer!davidg INET: davidg@killer.DALLAS.TX.US "...Different ship, but she's got the right name. Treat --Admiral L. McCoy her like a lady, and she'll always bring you home." "Encounter at Farpoint"
lee@sed170.HAC.COM (John Lee ) (12/23/88)
In article <742@zehntel.UUCP> donw@zehntel (Don White) writes: > > Can anyone at Commodore tell us why (in detail) the drives click? I know > they are looking for disk insertion, but HOW are they doing it and why? I'm not a Commodore person, but I play one on TV. :-) The drives click because they indicate the disk inserted/ejected status (via the /DISKCHANGE signal line, active when a disk has been inserted/ejected since the last head step) only AFTER the head has been stepped (click!) either in or out. This is stated in the A-W Amiga Hardware manual and in the Amiga Techical Reference manual. Now as to why you must step the head, I dunno. Since /DISKCHANGE is it's own separate signal, there's no reason why it can't reflect the disk status whenever the drive is selected, which doesn't require a head step (or by some other non-noisy method). In fact, wouldn't it be much easier if /DISKCHANGE was instead an active-on-select /DISKINSERTED? One quieter method that works on some drives is to try step the head backwards from track 0. This will still activate the diskchange flip-flop but since most drives can't move past 0, they don't click. This is done by several Kickstart hacks out there (NoKlickstart?) Unfortunately, some drives (like my brother's) will strike a mechanical stop and make an even louder click. > Don't all drives have some kind of hardware to tell you if a drive is > loaded? Couldn't drives be kept at one known location (like track 0) > where you KNOW there should be SOME information? ANd just do reads with > no more head positioning? It's MUCH faster and simpler to step the head and check /DISKCHANGE than it is to try to read the disk. > > ????? > Don White > zehntel!donw > Box 271177 Concord CA. 94527-1177 ^^^^^^^^^^^^^^^^^^^^^^ Gee, someone from my area (I'm from ZIP code 94518). ------------------------------------------------------------------------------- Raining CATS and DOGS? Join the RATS: Remote Amiga Teleconferencing System +--------+ | HUGHES | John Lee +--------+ ARPAnet: jhlee@hac2arpa.hac.com Hughes Aircraft Company The above opinions are those of the user and not of those of this machine.