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- Path: sparky!uunet!news.univie.ac.at!alijku11!k3027e7
- Organization: Johannes Kepler University Linz - Computing Center
- Date: Tue, 26 Jan 1993 14:59:56 CET
- From: <K3027E7@ALIJKU11.BITNET>
- Message-ID: <93026.145956K3027E7@ALIJKU11.BITNET>
- Newsgroups: comp.sys.cbm
- Subject: Re: 2 Q's: BMI & SAVE@
- References: <1993Jan22.062624.23025@netcom.com> <30370@optima.cs.arizona.edu>
- <1993Jan24.043922.20002@netcom.com> <C1Ds7u.M53@ddsw1.mcs.com>
- Lines: 40
-
-
- dattier@ddsw1.mcs.com (DWT) writes:
-
- >Specifying the drive number works. Scratching first and then saving does
- >not (unless you scratch, initialize, and then save). Thinking that
-
- My 1541 is 8 years old and so probably contains all the bugs
- existing. I have had trouble with messed up disks when using
- SAVE "@:name",8 .
- Since then I have been using OPEN 1,8,15,"s:name": SAVE "name",8 and
- I can't remember problems with that. Note that I never use drive
- numbers.
- So to find out for sure: Does anybody know a sequence of commands that
- generates this bug, so we can all check out our 1541s ?
-
- >be the result of carelessness about disk ID's and initializing. (The 1541
- >doesn't automatically initialize when a disk is inserted but only if the disk
- >ID is different.) Take a disk out of a 1541 and insert a different disk with
-
- Also the write protection lightbarrier is used to detect a disk change.
- This check is done during the IRQ-Routine. However during data transfer
- this routine can be disabled.
- Therefore you can savely use disks with equal IDs as long as you don't
- change disks while there is access to the drive by the computer.
-
- You can see the disk change detection work if you open a file and then
- remove the disk:
- Type OPEN 2,8,2,"NAME,S,W" and the red light will go on. When removing
- the disk the LED will go off as the 1541 detects the disk change and
- allows no further writing to the file.
- However if you type OPEN 2,8,2,"NAME,S,W":CMD 2 the light will stay
- on after removing the disk as the drive is listening for data from the
- computer and therefore not checking the lightbarrier. If you insert a
- new disk with an equal ID then the 1541 will continue writing it's file
- there and completely mess up the new disk.
- WARNING: Don't try this with disks that contain data you want to keep!
-
-
- Richard Hable
- k3027e7@edvz.uni-linz.ac.at
-