Re: [M100] M100 Digest, Vol 80, Issue 9

[Brian White]

err good grief yet another correction. I missed your very last line Josh,
which obviates my entire post. "oh well" indeed ;)

On Fri, Aug 11, 2017 at 6:18 PM, Brian White  wrote:

> I didn't notice that last post didn't include any quoting. Meant to reply
> to Josh, and neither contradicting nor adding to what Mike already said.
>
> On Fri, Aug 11, 2017 at 6:13 PM, Brian White  wrote:
>
>> 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.
>>
>>
>

Re: [M100] M100 Digest, Vol 80, Issue 11

[Robert Prather]

HI Kurt,

thanks. I remember Parallel for the PC, but wasn't sure with the connection
to the Model 100. I still have the cable, drive, ac adapter and disks. I
guess that ebay listing wasn't real. I guess the only real way would be to
make/find  a cable, etc..

Re: [M100] M100 Digest, Vol 80, Issue 9

[Brian White]

I didn't notice that last post didn't include any quoting. Meant to reply
to Josh, and neither contradicting nor adding to what Mike already said.

On Fri, Aug 11, 2017 at 6:13 PM, Brian White  wrote:

> 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.
>
>

Re: [M100] M100 Digest, Vol 80, Issue 9

[Brian White]

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.

Re: [M100] M100 Digest, Vol 80, Issue 9

[Mike Stein]

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: 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.

Re: [M100] M100 Digest, Vol 80, Issue 9

[Brian White]

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  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 
> *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.
>
>

[M100] M100 Contrast potentiometer (VR1) replacement

[Ian McLaughlin]

Hello all,

Does anyone have a suggestion for a replacement contrast potentiometer for a 
model 100? I have a machine that was working until someone ‘over-adjusted’ the 
contrast knob and it now spins freely, and therefore doesn’t work.  It’s not a 
mechanical issue with the screw and the knob, but rather inside the mechanism 
itself.

I tried a quick scan of Digikey but I can’t find anything with remotely the 
same form factor.  Wondering if anyone knows of a source for these, or has 
managed a repair with a substitute?

Thanks for any guidance.

Ian

Re: [M100] M100 Digest, Vol 80, Issue 9

[Josh Malone]

Depends on whether you consider the M100 to be "communications equipment"
or "terminal equipment". From the perspective of "this is a device to be
hooked up to your main PC" then female makes sense, somewhere. But I think
the port is wired as terminal equipment, which then puts it (technically)
in error.

Oh well :)

On Thu, Aug 10, 2017 at 11:11 PM, John R. Hogerhuis 
wrote:

>
>
> On Thu, Aug 10, 2017 at 7:22 PM, Brian White  wrote:
>
>>
>> * I heard someone suggest that actually the M100 was probably technically
>> correct according to the standards of the time, and predated the PC, and
>> it's actually the IBM PC that came along, backwards, and essentially made
>> everyone else change. This perfectly believable to me. So when I say the
>> M100 is "backwards", it's only in the sense that it is the exception now,
>> not that it is wrong.
>>
>>
> Well, a female DB-25 certainly makes more sense on a laptop. Avoids
> problem of pins getting damaged and wrecking your laptop instead of the
> cable.
>
> Another great design moment or accident of history that makes most of our
> Model 100's still functional 34+ years later.
>
> -- John.
>
>

Re: [M100] M100 Digest, Vol 80, Issue 9

[Mike Stein]

...
"in error" only if you consider the IBM PC and compatibles as the correct 
"standard".

As Brian pointed out, back in the days when computer users were (by necessity) 
more technically competent than the majority of users today, most interface 
connectors on equipment were female, regardless of whether they were DTE, DCE, 
serial or parallel, or even disk drive connectors. Cables were male on both 
ends and you were expected to read the label on the port and/or know or check 
what went where.

As John points out, if you bent or broke a pin you only had to replace the 
cable.

The advantage of the IBM male serial connector is that it helps to prevent 
plugging a serial cable into a parallel port or vice versa, which our original 
poster wants to do with his ZIP drive; because of the substantially different 
voltages and polarities this can fatally damage the parallel port.

m

- Original Message - 
  From: Josh Malone 
  To: m...@bitchin100.com 
  Sent: Friday, August 11, 2017 10:41 AM
  Subject: Re: [M100] M100 Digest, Vol 80, Issue 9


  Depends on whether you consider the M100 to be "communications equipment" or 
"terminal equipment". From the perspective of "this is a device to be hooked up 
to your main PC" then female makes sense, somewhere. But I think the port is 
wired as terminal equipment, which then puts it (technically) in error.


  Oh well :)



  On Thu, Aug 10, 2017 at 11:11 PM, John R. Hogerhuis  wrote:





On Thu, Aug 10, 2017 at 7:22 PM, Brian White  wrote:


  * I heard someone suggest that actually the M100 was probably technically 
correct according to the standards of the time, and predated the PC, and it's 
actually the IBM PC that came along, backwards, and essentially made everyone 
else change. This perfectly believable to me. So when I say the M100 is 
"backwards", it's only in the sense that it is the exception now, not that it 
is wrong.




Well, a female DB-25 certainly makes more sense on a laptop. Avoids problem 
of pins getting damaged and wrecking your laptop instead of the cable.


Another great design moment or accident of history that makes most of our 
Model 100's still functional 34+ years later.


-- John.