Path: utzoo!utgpu!news-server.csri.toronto.edu!mailrus!iuvax!dolmen!graham From: graham@dolmen.UUCP (James Graham) Newsgroups: comp.sys.amiga.hardware Subject: Re: PC 720k drives on Amiga HELP? Message-ID: Date: 7 Sep 90 13:47:09 GMT References: <4302@crash.cts.com> Lines: 77 >In article <4302@crash.cts.com> oleg@crash.cts.com (Oleg Rovner) writes: >I know this subject came up before, but I didn't save the thread, and now >I'm desperately in need of info, so please help. (Gawd, I sound like a >Televangelist :-) > >My external drive (an original 1010 from 1985) just ate it, or more properly >the drive mechanism did. Now, I was wondering if I could take a 720k IBM >drive mechanism that I have laying around and plug it in. So I did. It >doesn't work. The mechanism is plugged in place of the old drive mechanism >(ie the 1010 case/ic board) and I get two? problems, 1. No formatting (the >drive DF1: is BAD on bootup, formatting doesn't work, aborts with the >no sector header error on track 0) 2. Media change detection doesn't work. > >The drive model is Toshiba ND-3521GR, if someone could point me toward a >solution, or better yet, provvide one, I'll be eternally grateful. I'm presently using a Toshiba drive as DF1: on my system. To interface it, I tried two things. I read the tech manual and came up with a "prototype" interface, which consisted all of two IC's. If I recall, a 7474 ttl quad d-flipflop and a 7417 open-collector hex inverter. The important part is to get the Amiga to recognize the IBM drive as an AMIGA drive....hence the additional IC's. The amiga, during boot, expects a series of 1's and 0's from a single line on the external drive connector. The sequence of these bits determines what kind of drive is connected (sort of an ID code). That interface worked, but I experienced an occasional trashed floppy, probably due to flaky wiring or something to that effect. I was fortunate to have a friend who came across a dead amiga external drive. Since the heads were destroyed, the interface was intact. He gave me the interface and cable, and I made the pin translation between the drives, connected the interface to the Toshiba, and off it went. To this day I have had no problems. I tried two things to overcome the media change detection problem. First, I found the microswitch (in the Toshiba) that served as a disk inserted detector to the Toshibas internal circuitry (unfortunately, this was not brought out to the edge connector). I ran a wire from this, to the appropriate pin on my "home-built" interface and it half-way worked. When I installed the commercial interface, I simply connected a toggle switch between ground and the diskchange line on the amigas external connector. This was livable, but I got tired of flipping the switch and at other times, forgetting and experiencing gurus as a result. So, I found a pd program called "dc", which was compiled with drive df2: in mind. I modified the source for df1:, changed the graphics images to reflect the same, and recompiled. This way, there was an icon on the workbench screen that I could click when I changed disks. Anyway, I no longer have the drive connected since I now have a hard disk. If you are interested in my "prototype", let me know your smail address and I'll see if I can find the old drawings and send you a copy. I don't recommend it, however, because of the infrequent disk-trashing problem. -- ___________________________________________________________________ | **** JUST A REMINDER ***** | |"That to secure these rights, governments are instituted among men,| |deriving their just powers from the CONSENT OF THE GOVERNED. That | _|whenever any form of government becomes destructive to these ends, | | |IT IS THE RIGHT OF THE PEOPLE TO ALTER OR TO ABOLISH IT..." | | | (emphasis added) -- T. Jefferson, et al | | |___________________________________________________________________| |dolmen!graham@iuvax.cs.indiana.edu | Wow! Windows on |The Portal Dolmen BBS (812)334-0418, 24 hrs. daily|<- UUCP News!!!! |__________________________________________________|