Your use of "backwards" and "everything else" is mainly relative to IBM-PC 
compatible systems; some people don't realize that there were other computers 
before (and even after) IBM PCs and Apples.

As I said, with a few notable exceptions the usual rear panel connector for 
serial (DTE or DCE), parallel and some SCSI ports was a female DB25F; serial 
printers of the day also used a female DB25F connector.

In this context the Model T is essentially an intelligent terminal (DTE); have 
a look at the back panel of pretty well any terminal of the day (except DEC) or 
even a UNIX or CP/M computer and you'll probably find female DB25Fs.

The IBM PC with its unusual (for the time) male DB25M was just becoming 
mainstream at the time of the M100; as its popularity grew the various ways 
that it deviated from the conventions of the day became the new "standard" and 
the market for gender changers grew substantially..

The point is that when dealing with vintage equipment like the Model T or even 
an external modem do not assume that a female DB25 is a parallel port as IBM 
have (re)defined it.

m


----- Original Message ----- 
  From: Brian White 
  To: [email protected] 
  Sent: Friday, August 11, 2017 6:13 PM
  Subject: Re: [M100] M100 Digest, Vol 80, Issue 9


  It's wired as DTE, but with a female connector. *That's* what makes it 
backwards, not merely the female connector by itself.

  If it were a female connector, and wired as DCE, that would be unusual for a 
computer, but it would still be conforming to the same conventions as 
everything else.


  When you buy a random serial cable with male pins in a 25 pin connector, if 
you know nothing about the insides of the cable or where it came from or what 
the original packaging said etc, 99 44/100ths of the time that combination 
expects to be plugged into a modem, or other DCE device. The M100 isn't a 
modem, but if it's connector were wired DCE, that "modem" cable would still 
work.

  *today* such a plug would have an extra dimension of wrongness because it 
would be ambiguous with a printer port, but at that time, D25F might not yet 
have become a standard for parallel printer ports. It doesn't matter that the 
printer port on the M100 itself isn't confusable with it's own serial port, 
it's still a factor as long as a significant number of printers and their 
cables out there can physically plug in to the wrong port. At the time, that 
might not have been true like it absolutely is today.

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