joeg@lilink.UUCP (Joe Gelman) (06/20/89)
I've installed a Fujitsu 720K DS drive in place of the standard Atari
SS drive. (Direct swap into Atari's case). The drive works fine except for
it's failure to detect a disk change unless it's write-protected.
I traced the problem to a different signalling scheme at the pins
responsible for telling the ST about the swap. Does anyone have the fix for
this, or have I acquired the wrong drive for use with the ST?
--
PO Box: rutgers!lilink!joeg *simple, but will it work?*
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LILINK Public Access Xenix (516) 872-2137/2138/2349 1200/2400 Login: newclf3678@ultb.UUCP (C.L. Freemesser) (06/21/89)
In article <741@lilink.UUCP> joeg@lilink.UUCP (Joe Gelman) writes: > > I've installed a Fujitsu 720K DS drive in place of the standard Atari >SS drive. (Direct swap into Atari's case). The drive works fine except for >it's failure to detect a disk change unless it's write-protected. > > I traced the problem to a different signalling scheme at the pins >responsible for telling the ST about the swap. Does anyone have the fix for >this, or have I acquired the wrong drive for use with the ST? > > >-- >PO Box: rutgers!lilink!joeg *simple, but will it work?* >========================================================================= >LILINK Public Access Xenix (516) 872-2137/2138/2349 1200/2400 Login: new Run a jumper between pins 2 and 28 of the 34 pin connector on the drive. This SHOULD fix the problem. If you start to get WRITE PROTECT warning boxes after this jumper is connected, then you are out of luck. The signals aren't strong enough when the two lines are connected. I have this problem on my Teac. TOS 1.4 fixes this problem, so you COULD wait until it comes out. Chris Freemesser, Rochester Institute of Technology | What I like : BITNET: %clf3678@RITVAX | 1) My Atari ST USENET: Just reply and hope it gets through | 2) My '77 Mercury "Another brilliant mind ruined by higher education" | 3) Coke Classic
del@hpcupt1.HP.COM (Dan E lee) (06/21/89)
I added an external (toshiba) disc to my 520stfm recently and have seen this also. It seems the OS selects each disc and samples the WRITE PROTECT during vertical sync periods. If it detects the WP to be asserted anytime then it assumes that a disc change had occured. So swapping in a protected disc is always detected. Before you get around to access the disc, lots of samples have come back with the WP true. Now what about swapping a writeable disc for another writeable disc? This is probably the case where the new disc was not detected. So what happened? Didn't the WP go true when the disc was removed? The drive only has to appear write protected momentarialy and the write protect switch on the drive is in the same position it would be for many samples during the time after the old disc is removed until the the time that the new disc is inserted. Well there's the problem. Most drives I've seen will not assert WP if there is not disc in the drive so you don't get the writeable to write protected to writeable transitions in the WP line you might expect. I don't have a specific fix for you disc but if you think your problem caused by what I described above then you might try the following. If your drive has a DISC CHANGE signal on it (usually pin 2 sometimes pin 34) you can hook this line to your WRITE PROTECT line. This will solve you problem of recognizing a new disc but this can lead to other problems on some drives (in my case writeable discs sometimes appeared protected and the fix is another long story).
chad@norge.dec.com (06/23/89)
I too added a toshiba DSDD drive to my 520 STFM. I too had the problem of non-protected disks not signalling media change. Someone in my company sent me some USENET articles from long ago discussing this. I added a 1n1418 diode from pin 34 (most drives use 2 -- head load here, mine had pin 34 as media change detect so I used that instead) to pin 28, write protect detect. It should modulate the signal from 2/34 onto pin 28, write protect detect. This should fix the media change problem. However, this leads to another problem in some drives. Non-protected disks sometimes appear write protected. Wht I ended up doing (just a couple days ago in fact) was to buy a $0.40 slide switch at Radio Shack and to switch the diode. I normally leave it closed for media detection but now when I have non-protected disks showing up protected I just flip the switch and all is as normal. Chad