D-shell sizes [was Re: Slightly rare Mac 512k with D(?)-25
ard at p850ug1.demon.co.uk
Wed Sep 5 17:18:58 CDT 2007
> The 25-pin size - the one used for the MAC SCSI you refer to, the one
> called for by the mechanical portion of the RS-232 spec, the one used
> for peecee parallel ports - is DB.
> Using pin count for that same pin spacing, the table is DA=15, DB=25,
> DC=39 (I think), DD=50 (three rows), DE=9. The DE shell is also used
> in a 15-pin variant ("VGA"), but the pins are spaced substantially
> closer than in the DE-9. DA is probably best known for peecee joystick
In the high-density range, the standard sizes seem to be (in increasing
shell size) :
> connectors, but it also got used for AUI Ethernet back in the 10base5
> days, before even 10base2, much less 10baseT. DC doesn't get used much
> in my experience; I think I have a few SBus cards that use it for the
The common uses (on various machines) are :
DE9 : MDA, CGA monitors, PC/AT serial ports, some DEC printer (serial)
ports, Commodore/Atari Joysticks
DA15 : PC joystick, BBC micro analogue port (joystick :-)), AUI ethernet
DB25 : Real RS232 ports, PC parallel ports, Mac SCSI port, IEC625
interface (IEEE-488 on a DB25 connector!)
DC37 : PC external floppy interface. Some QIC tape interfaces. Canon 'VDO'
direct laser printer engine interface.
DD50 : Sun (and PERQ 3A) SCSI interface
DE15 : PC VGA (and higher) video
DA26 : Not seen it
DB44 : Not seen that either
DC62 : PC expansion unit
DD78 : Some HP multple seiral ports
Of course all these connectors were used for many other things besides
(my ACW has a DB25 keyboard socket, a DB25 user port and a DC37 '1MHz
bus'. I've wired all my HP 8-bit parallel interfaces for the 98x0 and
9815 to DC37 sockets, and so on). and they're used on things other than
> I don't know why they are out of order. I speculate that someone
> designed DA through DD, never expecting D-shell to get used for
> anything under 15 pins, then had to tack on the 9-pin size later.
> (Arguably they should have called it D@, but that would probably have
> been too geeky. :)
I bleieve that's correct. Also '@' is 'letter 0' only in ascii :-)
> There exist D-shell connectors of other sizes, like the NeXT "black"
> hardware video connector (which held something like 19 pins). I don't
> know whether they have names in the DA..DE series; I suspect they have
> no standard names because they're not standard sizes.
I've heard them called the 'DF19' and 'DG23' (Amiga video connector?) but
I don't know how official that is. Probsbly not at all!
I've heard that HP used 3 pin and 5 pin D-shaped seiral connectors on
some of their older machines. Were these DE-size shells or something else?
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