Re: Handshake cable

[dempson@atlantis.actrix.gen.nz (David Empson)]

In article <3nf79f$jo4@india.lm.com>,
Matt Portune <mportune@telerama.lm.com> wrote:
>
> Ok, I busted out the ol' multimeter and ran some tests, and both my 
> cables came out like this...
> 
>      mini 8 -  DB25
> 	2	5
> 	1	4, 20
> 	5	3
> 	4, 8	7
> 	3	2
> 	7	not connected
> 	6	not connected
> 
> I guess since pin 7 on the mini 8 is not connected to pin 8 on the DB25, 
> I don't have a properly wired cable.  Makes me laugh, considering BOTH of 
> these cables were supposed to be handshaking cables.

As I mentioned to you in E-Mail (but I"ll repeat here for the benefit
of others): the above _is_ a hardware handshaking cable: it has the
handshake signals from the computer connected to CTS and RTS.

All it is missing is the carrier detect signal, which is optional, and
is not supported on several low-end Macs (Plus and LC, for example).

Spectrum will work fine with this cable as long as you tell it that
DCD is not valid.  It will then behave as if you are always online,
and will use a built-in beep (or so the manual claims - I haven't been
able to verify this) that doesn't lock out interrupts.

If you have Twilight II, it will always background blank.

It is defintely preferable to have a hardware handshaking cable that
also supports DCD, since this allows the communications program to
easily detect loss of carrier (this is essential for BBS software).

> Is there a quick hack I can perform

If you can open up the DB-25 end, check to see if there are any loose
wires inside the cable: it might actually have 6 to 8 wires, but they
didn't bother connecting the DCD signal at the DB-25 end.  If there
are loose wires, one of them will probably be connected to pin 7 at
the IIgs end.

On the other hand, it might only have five wires in the cable.  If
the Mini-Din-8 end is moulded into the cable (as is common) it will be
easier to buy or make another cable.
-- 
David Empson
dempson@actrix.gen.nz
Snail mail: P.O. Box 27-103, Wellington, New Zealand