Re: Imagewriter II cable

["william strutts" <wrstrutts1@home.com>]

"Rubywand" <rubywand@swbell.net> wrote in message
3B2B6594.803C1E59@swbell.net">news:3B2B6594.803C1E59@swbell.net...

>      Sounds a lot like a Mac <--> IW-I cable. It seems like a good bet to
work
> as a IIgs <---> PC NULL modem cable. Probably, the 25-pin end is a male
> connector; so, you would need a female <--> female adaptor to have a way
to
> plug the cable into a PC COM port.

Yup.  Actually I need the 25 f-f gender changer plus my 25 pin to 9 pin
adapter.

>      The absence of a connection to pin 5 on the Dsub-25 connector
indicates
> that the cable will, most likely, not support hardware handshaking between
the
> GS and PC. Exactly how important hardware handshaking may be for a GS <-->
PC
> connection remains unclear.

Oh well.  So it wouldn't have enough lines for a modem not that I plan on
getting one.

>      About a month ago I ordered a Mac IW-1 Printer cable (950-0107) and a
Mac
> High-Speed Modem cable (950-0109) on-line from Radio Shack. (BTW, got very
good
> service; with regular postage, the cables arrive in a couple days.)  The
idea
> was to test performance of different transfer setups for sending files
back and
> forth between a IIgs and a PC.

Does the web site have different stuff than the store?

>      Mapping the lines for each cable showed that the IW-1 cable lacks the
> connections to support hardware handshaking. The Mac High-Speed Modem
cable
> supports hardware handshaking. (It does not have the connection to support
> RS-423 operation-- recommended for very long cables; but, that is probably
not
> important since the cable is just 10' long.)

So they're still available.  What was the cost?

>      My usual cable is an Apple IIgs High-Speed Modem (as described in the
> Spectrum manual and Modem Works manual).  It is identical to the Mac
High-Speed
> Modem cable with the addition of a line to support RS-423.
>
>      The GS <--> PC connections I tried out were ...
>
> o- Apple IIgs High-Speed Modem cable + NULL modem adaptor
>
> o- Mac High-Speed Modem cable + NULL modem adaptor
>
> o- Mac IW-1 Printer cable + female-female adaptor.
>
>
>      The testing involved regular Z-modem file transfers with HyperTerm
running
> on a 233MHz PC and Spectrum running on the IIgs (ROM-01 with 4MB and 10MHz
> ZipGSx accelerator).  For IW-1 cable tests, the PC port was set Xon/Xoff
flow
> control.
>
>      It was something of a chap to find no difference in performance!
Setting
> hardware handshaking or software flow control made no difference with any
of
> the cables except for the IW-1 cable, which would not work at all with
hardware
> flow control.

No difference?  I found differences in protocols used.  There was a 2k
penalty
for using Xmodem versus Ymodem.  Z-link doesn't support Zmodem and
I found a copy of Proterm but it wouldn't support transfers faster than 19K.

>      The only significant impact on transfer speed came from slowing down
the
> IIgs. With no acceleration, the GS could not maintain transfers above
about 38k
> baud. And, again, hardware or software flow control did not matter.

Okay, that jives with what I am getting.  I have an unaccelerated GS and I
can't get it to work faster than 38k.

>      Of course, these results relate to just GS <--> PC transfers running
the
> software mentioned. When it comes to selecting a cable which works well
with
> all sorts of telecom software, support for hardware flow control and
having
> other lines connected could make a big difference in results.

Didn't you just demonstrate that it didn't make much of a difference?

--
--
William R. Strutts - wrstrutts1@home.com - Whatever!

C'est moi!  http://www.facelink.com/wrstrutts

Just hacking away...