I don't disagree on any point. Sorry for the way that post sounded. On Fri, Aug 11, 2017 at 7:13 PM, Mike Stein <mhs.st...@gmail.com> wrote:
> 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 <bw.al...@gmail.com> > *To:* m...@bitchin100.com > *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. > >
