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From: oster@lapis.berkeley.edu (David Phillip Oster)
Newsgroups: comp.sys.mac,comp.sys.ibm.pc
Subject: Re: IBM PC -> Imagewriter
Message-ID: <2260@jade.BERKELEY.EDU>
Date: Mon, 19-Jan-87 14:50:23 EST
Article-I.D.: jade.2260
Posted: Mon Jan 19 14:50:23 1987
Date-Received: Tue, 20-Jan-87 23:03:03 EST
References: <1088@edison.GE.COM>
Sender: usenet@jade.BERKELEY.EDU
Reply-To: oster@lapis.berkeley.edu.UUCP (David Phillip Oster)
Organization: University of California, Berkeley
Lines: 83
Keywords: Technical Info Requested
Xref: mnetor comp.sys.mac:853 comp.sys.ibm.pc:1109

The imagewriter I is basically a re-packaged C. Itoh printer (proprinter,
I think it is.) It defaults to 9600baud DTR-handshaking (It handshakes for
data on pin 20.) RS232-C standard Data Terminal (as opposed to data-modem)
device. To interface it to an IBM PC, you need a null modem cable, since
the PC's serial ports are also RS232-C Data Terminal devices. The
Imagewriter II is electrically and electronically almost the same, but has a
different cable end. I say _almost_ because it accepts a superset of the
control codes of the imagewriter I and because it was designed to be
compatible both with RS232-C and with Apple's Appletalk network. 
To get this network compatibility Apple sacrificed power in the RS232-C
line-drivers in the Imagewriter II. Therefore I recommend using a cable
shorter than 12 feet long.

Here are the pinouts of the various plugs:
Apple's standard DB-9 9-pin connector as found on the back of Macs:
Pin	Name	Notes
1	Ground
2	+5v	absent on a MacPlus
3	Ground
4	TxD+	Transmit data plus (rs422-balanced line)
5	TxD-	Transmit data
6	+12v	you are strictly limited in the dat you can draw on this
7	HSK	Handskake - CTS or TRxC depending on Zilog 8530 mode
8	RxD+	Recieve data line (ground to emulate rs232)
9	RxD-	Recieve data minus

Imagewriter 1 DB-25 connector
Pin	Name	Notes
1	Frame Ground 
2	SD	Output from Imagewriter
3	RD	Recieve data - input to Imagewriter
4	RTS	Ready To Send - output handshaking line from imagewriter
7	Ground	signals are referenced to this
14	FAULT-	False when deselected, output from Imagewriter
20	DTR	Data terminal Ready - output from Imagewriter

The important ones are 3 7 and 20.

The Mac to Imagewriter cable uses
Mac Pin	Name		Imagewriter Pin	Notes
1	Ground		1
3	Sig.Ground	7		Mac pins 3,8 are jumpered together
5	TxD-  --> RD	3		Data to Imagewriter
7	HSK   <-- DTR	20		Handshake from Imagewriter
8	RxD+ (MacPin3)			Not connected on Imagewriter side
9	RxD-  <-- SD	2		Data from imagewriter

The mac queries the imagewriter for an id code, so it can adjust itself to
what model of imagewriter it is talking to. Ordinarily, you should not
need to worry about this.

My guess on the cable you'll need to connect an imagewriter I to an IBM
is:
IBM Pin	Name		Imagewriter Pin Notes
2	SD --> RD	3		Main printer data
3	RD <-- SD	2
4,5	RTS <-- DTR	20		IBM pins 4,5 are jumpered together
7	signal ground	7
6,8,20	DTR				IBM pins 6,8,20 are jumpered together

If you have an imagewriter II, you'll need the following conversion
between the Mac DB-9 connector and the Mac DIN-8 connector.

looking at the pins of a male cable, the DIN-8 pins are numbered:
   6 7 8
   3 4 5
    1 2
The adapter cable, Apple Part # M0187, cable assembly part #590-0341-A
available at an apple dealer for about $15.00 is wired
DIN-8 pin	Name	DB-9
1	+12v	6
2	HSK	7
3	TxD-	5
4	Ground	3
5	RxD-	9
6	TxD+	4
7	not connected
8	RxD+	8

This information is my interpretation of Apple Tech Notes 10 and 65.
--- David Phillip Oster		-- "The goal of Computer Science is to
Arpa: oster@lapis.berkeley.edu  -- build something that will last at
Uucp: ucbvax!ucblapis!oster     -- least until we've finished building it."