[ont.micro.mac] wiring up an external disk drive

info-mac@utcsrgv.UUCP (info-mac) (04/26/84)

Date: Wed, 25 Apr 84 10:43 PST
From: Bill Croft <uw-beaver!croft@Safe>
Subject: wiring up an external disk drive
To: info-mac@sumex
Cc: croft@Safe

If you happen to have a spare SONY disk drive (like the one inside
your LISA) that you aren't using all the time, you can try hooking
it up as a 2nd drive on your Macintosh.  Here's the wiring diagram:

Mac, 19 pin D		Function	SONY drive, 20 pin
connector, J4				Berg conn, J5

	1		gnd		1
	11		phase 0		2
	2		gnd		3
	12		phase 1		4
	3		gnd		5
	13		phase 2		6
	4		gnd		7
	14		phase 3		8
	5		no wire		9
	15		wr req/		10
	6		+5V		11
	16		hd sel		12
	7		+12V		13
	17		enable/		14
	8		+12V		15
	18		rd mpx		16
	9		no wire		17
	19		wr data		18
	-		no wire		19
	10		pwm		20

We are having a hard time finding the 19 pin D connector; however the
part number for the female side in the Mac is AMP 745971-1, so AMP
should have a matching male connector.

Take care when aligning the Berg connector on the back of the SONY
drive.  Line up the arrows.  When looking at the back of the drive,
pin 1 is in the upper right corner.

Good luck, we'll let you know when the smoke clears...

info-mac@utcsrgv.UUCP (info-mac) (04/26/84)

Date: Wed, 25 Apr 84 13:21 PST
From: Bill Croft <uw-beaver!croft@Safe>
Subject: Re:  wiring up an external disk drive
To: info-mac@sumex
Cc: croft@Safe

Since we are still waiting on the 19 pin D connectors from AMP,
Nick Veizades, our hardware wizard, figured out this hack:  Take
a 20 cond ribbon cable and put a Berg on each end and another Berg
about 6 inches from one end.  Use the close pair to daisy chain from
the Mac CPU board to the internal drive and out a slot in the back
(over the top of the 19 pin D works fine).  Since wire # 14 is the
enable line (to the internal drive), cut this wire in the ribbon
cable.  Solder a pin on the other side of wire # 14 and stick it
in pin # 17 of the D connector (external drive enable).

The dual drive Mac works great.  A disk-disk copy takes about a 
minute with no disk swaps.  Programs using the "standard file"
file opening dialog (such as MacPaint) have a "drive" box that
toggles the current drive.  In the finder, new disks just appear
on the desktop when you insert them.

info-mac@utcsrgv.UUCP (info-mac) (04/27/84)

Date: Thu, 26 Apr 84 14:37:54 EST
From: Bob Rees <uw-beaver!rrees@BBN-UNIX>
Subject: Re: wiring up an external disk drive
In-Reply-To: Your message of Wed, 25 Apr 84 10:43 PST
To: Bill Croft <croft@Safe>
Cc: info-mac@sumex

I have never seen one of the Mac external disk drives (and neither
has my local Apple dealer!).  Does it get all its power from the
Mac via the 19-pin connector, or does it contain its own power
supply & AC line cord?

info-mac@utcsrgv.UUCP (info-mac) (04/27/84)

Date: Thu 26 Apr 84 20:18:20-EST
From: Michael Rubin <uw-beaver!RUBIN@COLUMBIA-20.ARPA>
Subject: Re:  wiring up an external disk drive
To: croft%SUMEX-VAX@SU-SCORE.ARPA
Cc: info-mac@SUMEX-AIM.ARPA, croft%SUMEX-VAX@SU-SCORE.ARPA
In-Reply-To: Message from "Bill Croft <croft@Safe>" of Wed 25 Apr 84 22:04:51-EST

Another way to fake the 19-pin D connector is with an ordinary 25-pin
connector and a hacksaw... just be careful about alignment when you
plug it in.  The same hack [pun intended] also applies to the 9-pin
serial port connector.
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