Re: Will Apple Disk ][ work on IIGS

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

In article <cp62331@pro-sol.cts.com>, Tom Kelly <tomk@pro-sol.cts.com> wrote:
>
> Actually, you CAN use a Disk II on a IIgs directly off the drive port.
> 1) You need a adapter cable to replace the existing 20 conductor cable and
> connector with one terminated in a DB-19 connector.
> 2) You can only use ONE and it must be at end of the chain.

You can use two Disk ][s if you make a double adaptor cable (one wire
needs to be moved between the first and second plugs).


Here are the details for making a single or double adaptor for
connecting a Disk ][ to a IIgs or IIc+ (or a single Disk ][ to a IIc).

The reverse (connecting a UniDisk 5.25 to a Disk ][ controller) is
also possible - reverse the sex of the connectors.

Note: make these cable at your own risk!  If you get anything wrong,
you could damage your drives, disk controller and/or computer.


You require a 20-way ribbon cable, preferably no longer than 4 inches
(less length to radiate RF), a 20-way male ribbon-cable mounted plug
("insulation displacement"), and a DB-19 male plug (ribbon cable mount).

Crimp the DB-19 onto the cable (peel back the 20th wire at this end,
but do not cut it off yet).

The IDC-20 should be crimped to the other end.  Pin 1 of the DB-19
should go to pin 1 of the IDC-20.  (Note the difference in numbering:
the DB-19 is numbered horizontally, the IDC-20 vertically, with the
pin numbers on the IDC-20 corresponding to the wire numbers on the cable.)

A few wires need to be relocated.  The best way is probably to cut the
wires a little distance from the IDC-20.

Wire 17 should be cut.  Wire 19 needs to be rerouted from IDC-20 pin
19 to pin 20, so use whatever method you see fit - cut wires 19 and 20,
and then connect wire 19 from the DB-19 to wire 20 from the IDC-20.

The finished product should have connections as follows:

DB-19       IDC-20     Function

1-4         1,3,5,7    Ground
5           9          -12 volts
6           11         +5 volts
7-8         13,15      +12 volts
9           n.c.       Drive 2 select
10          20         Write Protect
11-14       2,4,6,8    Stepper motor phases
15          10         Write Request
16          12         +5 volts
17          14         Drive 1 select
18          16         Read Data
19          18         Write Data

The cut pins 17 and 19 are both +12 volt inputs to the drive.

If you want to add a connector for a second drive, it has all signals
in parallel with the first connector, except that IDC-20 pin 14 should
come from DB-19 pin 9 (drive 2 select), and DB-19 pin 17 should not go
to the second connector.

I have double-checked the numbers in the table above, so if there are
any discrepancies between the table and the description, the table is
probably correct.
--
David Empson
dempson@actrix.gen.nz
Snail mail: P.O. Box 27-103, Wellington, New Zealand