Date : Wed, 17 Mar 1999 15:37:45 +0000
From : "Christopher J Thornley" <C.J.Thornley@...>
Subject: Re: 3.5 inch disc in Master
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Some drives will have trouble because they default to HD moded this can be
altered by applying a +5v to pin 2 of a disk drive should switch it into DD
mode. i.e in HD mode the motor spins at 360rpm and in DD mode it should spin at
300rpm like 3,5inch drive.
Also the Diskchange and Ready lines are some times exchanged on drives or simply
not present
and the access times of the drives are a lot faster so appropiate jumper have to
be changed on the BBC Keyboard.
Ill quote some information I found on the problems with diskdrive in an amiga
document
Quote ============>
Connections & Connectors
In this you can see the connections
Connections to PC drive (34 pins Shugart bus)
The connector for the power supply consists of 4 pins:
pin 1: 5 volt
pin 2: Ground
pin 3: Ground
pin 4: 12 volt
It is important not put this connector in the wrong way. You probably will wreck
your drive !!! Normally it should be very difficult to do this, but I can assure
you it can be done. Just try it out with the power off and see for yourself
which way fits best. By the way I read that for the 5.25 inch drives with the
bigger connectors pin 1 is 12 volt and pin 4 is 5 volt !!
I checked out some books and magazines to give you some detail on the drive
connector. Only the even number connections are used for signals. The odd
numbered pins are connected to ground.
PIN 2: DISKCHANGE Output signal. This is a tricky one to start with. It is
used for a number of different signals by each manufactorer. The first one is
the most widely spread used. DISKCHANGE is perfect to use for the amiga
diskchange signal. HIGH DENSITY/DOUBLE DENSITY input signal to switch drive
motor between 300 and 360 rpm. Only used for 5 1/4 inch floppy drives. IN USE
input signal for letting the drive know something is coming up soon. Also used
for driving led at front of the drive. HEAD LOAD input signal for the drive to
put the head to the disk and pre magnetise it. (Rarely used)
PIN 4: IN USE Another pin use in more ways than one IN USE is the most likely
candidate. see pin 2 (Sometimes you can have DISKCHANGE and HEAD LOAD). With
internal Amiga drives IN USE is always connected to the MTRX signal. So when the
motor is spinning the LED is on.
PIN 6: DRIVE SELECT 3 see PIN 10. Pin 6 is sometimes used for the READY
signal (see PIN 34).
PIN 8: INDEX output signal will be low when the magnet on the flywheel of the
drive passes the Hall sensor (when drive SELECT is low).
PIN 10: DRIVE SELECT 0 input signal for selecting the last drive which is
then connected to this line. You will have to get the drive jumpers set to the
drive select you want. Normally the drives are left with the jumper on SELECT 0
and the cable is twisted to change select lines (Yes that's why there is a
twist).
PIN 12: DRIVE SELECT 1 see pin 10
PIN 14: DRIVE SELECT 2 see pin 10
PIN 16: MOTORON input signal switches to motor on. Sometimes the amiga way of
switching on the motor with DRIVE SELECT can be set with a jumper on the drive.
PIN 18: DIRECTION SELECT Input signal. When low stepping direction of the
head is to the axis (inside) of the disk. High is to the outside of the disk.
PIN 20: STEP Input signal. With every low pulse the head is stepped to the
next (by pin 18 determined) track when the drive is selected.
PIN 22: WRITE DATA Input signal. Here the data to be written on the track is
coming in from the computer.
PIN 24: WRITE GATE Input signal. When low the data from pin 22 is written on
the disk.
PIN 26: TRACK 0 Output signal. When the head is above the first track this
line will be low when SELECT is active.
PIN 28: WRITE PROTECT Output signal. When the write protect hole is open
(disk is write protected) and SELECT is low this signal will be low.
PIN 30: READ DATA Output signal. When SELECT is low then the data on the
track is written to this line.
PIN 32: SIDE 1 SELECT Input signal. When the SELECT is active this line set
the head (upper or lower) on which side is selected.
PIN 34: READY Output signal. Low when SELECT is active and the disk is
spinning at the right speed (INDEX signal) or, in a older simpler version, if a
disk is in the drive. It tells the computer that the drive ready to do a read or
a write of the track. The signal is high when the drive is empty (no disk), when
the motor isn't running or the motor is running too slow. Also very shortly
after a Head step signal it is high (15 ms). You see in this way the drive is
not mounted by the amiga! (Rarely used as DISKCHANGE or IN USE).
End Quote ==============>
Chris
"Mark Usher" <marku@...> on 17/03/99 13:10:36
To: "BBC MICRO Mailing List POSTINGS" <bbc-micro@...>, "Fraser, Colin
J" <Colin.Fraser@...>
cc: (bcc: Christopher J Thornley/CMS/University of Salford/GB)
Subject: RE: [BBC-Micro] 3.5 inch disc in Master
Hi
> Has anyone tried a 1.44M PC drive on a BBC and found it didn't work ?
> It might be worthwhile keeping a record of drive models that do work.
I wrote a lengthy article discussing this. It can be downloaded from the BBC
lives.
ftp....\bbc\doc\DiskDriveAndDFSGuide.zip
There is a table at the end that lists many many drives up to the 720k
variation.
I have a master list here on my hard drive that also contains the 1.2 &
1.4MB drives.
The criteria for the 1.4MB High density drives to work on a BBC is that it
must be able to switch to double density. Usually this is automatic when you
insert a DD disk.
Mark
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