12 Apr
2001
12 Apr
'01
8:28 p.m.
What this really says is that in order to connect two devices, you have to know
precisely what you're doing. That's hard, nowadays, when the mfg's documents
are printed in large type on a business card. Things have gone downhill.
Manufacturers don't provide documentation because nobody reads it.
Dick
----- Original Message -----
From: "Tony Duell" <ard(a)p850ug1.demon.co.uk>
To: <classiccmp(a)classiccmp.org>
Sent: Thursday, April 12, 2001 12:50 PM
Subject: Re: 50 pin SCSI to 50 pin centronics
So presumably using an all-pins-wired cable to link it to some true RS232
device that happens to implement all the pins is a good way to let magic
smoke out...
I've actually seen a device that has a single DB25 with the stnadard set
of RS232 signals on the stnadard pins (1-8 and 20 I think), and a
TTL-level Centronics-like parallel port on the other pins. Now that is a
device that you certainly don't connect to just any RS232 port.
I have done (and a DIN14, which is actually easier to wire than the
DIN13). I still think the mini DIN 9 is the worst to do (it was used on the
mouse port of the Archimedes, for instance), and the mini DIN 8 is only
slightly better than the 9 (and a lot worse than the DIN 13 and DIN 14).
-tony
IIRC, the RS232 standard specifies a 25 pin connector.
So strictly there
are no 9 pin RS232 ports. If you mean why do PC/AT machines have a DE9P
for the serial port, it was because (a) 9 pins is enough for the active
signals on said port and (b) you can fit a DE and a DB on a single PC
bracket, so you could have a combined parallel/serial adapter card. Which
IBM introduced with the PC/AT IIRC.
Oh, but then you lose a lot of fun. The Amiga DB25 serial port features
among others audio output on some pins. =) And Apple used the 8 pin mini-DIN on the Mac+ and
later because there
wasn't room for the DE9 connector used on the earler Macs. Hardware
hackers have been complaining ever since -- those mini-DINs are about the
worst connectors in the world to wire!
Try a DIN-13 for size.