johnf@sag4.ssl.berkeley.edu (08/10/88)
Hey folks,
I have a small puzzler, the answer to which I suspect might
be common knowledge among the Amiga cognoscenti (I am a neophyte of 3-4 months).
I decided it would be fun to try and hook up a surplus 5.25" drive to my
external drive connector (I have an A500). I built a small interface circuit
from an article on one of the Amicus disks written by someone named Marty,
which basically translates the Amiga MTRXD* signal into a form expected
by IBM-compatible drives, got a power supply for the drive, and made
up the cables. Finally, I changed the example mountlist entry for the
5.25"drive to reflect the fact that I was hooking it up as DF1:
After playing around with the jumpers for a while on the drive (a
1/2 height, 360K Mitsubishi model M4851-352U) I have it in a
configuration where it _almost_ works. The hardware seems to be in
fine shape, but mounting the drive is peculiarly difficult:
1) If there is a disk in the drive when I reset the Amiga, the drive
is automatically mounted as df1:, but the mountlist entry is ignored.
The Amiga assumes that it is an 80-track drive. Thus, when I try
to format a disk, all goes well until the drive bangs its head
against the wall trying to access tracks 40-79. Kind of amusing, actually.
2) If there is no disk in the drive at boot time, the drive is never
recognized. Mount does create a logical device DF1:, but format reports
an inability to locate its handler. I note that its
handler, "trackdisk.device", is nowhere to be found on disk, but I
assume that it is in the roms or something. I tried PCFormat from
the Extras disk, though I ultimately want to use the drive as
an AmigaDos disk, but it just gurus.
I just can't seem to get the computer to mount the drive properly. Any takers?
john flanagan
johnf@sag4.ssl.berkeley.educmcmanis%pepper@Sun.COM (Chuck McManis) (08/11/88)
[I nominate this one for the intro posting. :-)] In article <13132@agate.BERKELEY.EDU> johnf@sag4.ssl.berkeley.edu () writes: >I just can't seem to get the computer to mount the drive properly. Any takers? >john flanagan When connecting a 5.25" disk drive to your Amiga you need to take into account the "Drive ID." This is the signal that the drive sends back to the Amiga to tell the Amiga if it is an 80 track or 40 track drive. In the Amiga schematics this is implemented as a flip-flop for the 5.25" drive that returns 1010101010 as opposed to the 3.5" drives which return 11111111. When you leave this circuit out you get the 1111111 pattern and so your Amiga thinks it is a 3.5" drive with 80 tracks. Of course the A1000 schematics package from CATS includes the schematic for the little board they put on the A1020 drive, and that is the best place to get the information from. [You know the litany $20 to CATS, 1200 Wilson Dr, West Chester, PA, 19380] --Chuck McManis uucp: {anywhere}!sun!cmcmanis BIX: cmcmanis ARPAnet: cmcmanis@sun.com These opinions are my own and no one elses, but you knew that didn't you.
lai@vedge.UUCP (David Lai) (08/15/88)
In article <13132@agate.BERKELEY.EDU> johnf@sag4.ssl.berkeley.edu () writes: > > [says amiga recognizes his 5.25 40tk drive as an 80tk if disk is > in and no drive when disk is out at powerup.] > >johnf@sag4.ssl.berkeley.edu Looks like your 'rdy' line is being read by the startup boot code. It reads all 1's when a disk is in, and all 0's when no disk implying 1) standard 80tk disk and 0) no drive. You'll probably have to kludge a circuit to return alternating 1's and 0's so it recognizes it as a 40tk., or do something about the rdy line. -- "What is a DJ if he can't scratch?" - Uncle Jamms Army The views expressed are those of the author, and not of Visual Edge, nor Usenet. David Lai (vedge!lai@larry.mcrcim.mcgill.edu || ...watmath!onfcanim!vedge!lai)
johnf@stew.ssl.berkeley.edu (John Flanagan) (08/18/88)
Thanks to all who helped, especially Udi Finkelstein, who sent me a schematic for the drive i.d. code. I now have the 5.25" drive working. --john flanagan