Re: Apple disk //c pinouts?

[dempson@actrix.gen.nz (David Empson)]

Mike deWit <palatine@pobox.com> wrote:

> Hiya,
> Does anyone have pinouts for the 5.25" Disk //c that went with the Apple //c?
> It's a DB20 connector.

It is actually a D-19 connector.  (I'm not sure which letter is
appropriate after the 'D', but it isn't 'B', which indicates a connector
the same size as the DB-25 used for serial and parallel ports, and for
the SCSI connector on the Mac and Apple II.)

My main question: why do you need the pinout of the Disk //c?  The only
practical use for it would be to make an adaptor cable to connect a Disk
//c to a Disk ][ controller card (IDC-20 male connector), or to connect
a Disk ][ to an Apple //c.

You cannot connect a Mac 3.5" drive to a //c.  The only 3.5" drive
supported by the //c (given the right firmware in the computer) is the
UniDisk 3.5, which already has the right connector.

Here is the pinout of the IIc drive connector:

1-4    Ground
5      -12V
6      +5V
7-8    +12V
9      External Interrupt (not used by disk drives)
10     Write Protect
11-14  PH0-3 (stepper motor phases)
15     Write Request
16     Not connected
17     Drive Enable
18     Read Data
19     Write Data

On other D-19 disk controller ports used on Apple II models (including
the IIc+), pin 9 is the drive enable for the second external drive.  In
a UniDisk 5.25, pin 17 is used to enable this drive, and pin 9 is
rerouted to pin 17 on the piggyback connector.

In addition, pin 16 is expected to be connected in parallel to pin 6
(+5V) on some drives.

The signals defined here are used for different purposes by different
types of drives.  For example, the Apple 3.5 Drive uses the phase
outputs and write protect input to provide access to 1-bit mode and
status registers; the UniDisk 3.5 uses the phase lines to implement the
SmartPort handshaking protocol.

-- 
David Empson
dempson@actrix.gen.nz
Snail mail: P.O. Box 27-103, Wellington, New Zealand