[ct-user] LPT1 initialization with CT10.004 and the SCKII

Mark Bailey kd4d at comcast.net
Sun Feb 8 21:46:51 EST 2004

Good evening:

I have had the opportunity to do more testing with the SCKII and CT10.004.

John Evans, N3HBX, and I have had problems with the SCKII going into
record modes or otherwise acting strangely when starting CT.  There are
two different things happening.

First, CT is NOT clearing the DVK control pins on LPT1, even if the DVK
is enabled on LPT1.  This means that if any of the lines are high, the SCKII
tries to go into record mode.  This happens a lot if the computer is booted
into Windows 3.1 or something and then an exit to DOS is performed.

There are SIX of these lines going to the DVK, though CT only supports
four of them.  These lines are mapped to the DATA register of lpt1. (There
is actually a seventh line (DVK Abort)).

The only work-around we've found is to run another program to clear the
DVK control lines before running CT and before turning on the SCKII.

Second, CT is enabling the PTT line on LPT1 when it is started.  Starting
CT with no .bin file, and creating a new one, is causing PTT to be enabled
until setup is complete.  It turns out that this happens ONLY if the strobe
line on LPT1 is high when CT is started.  This means this only happens the
FIRST time you run CT.  The second time you run CT, strobe is already
low and PTT does not get asserted.  It may be that the radio 1/2 select
pin is also not correctly initialized.

Also, apparently, PTT is never cleared unless LPT1 is selected as the
CW port, even in SSB mode.

This behavior is causing problems if an SCKII is connected to the parallel
port, at least on some computers.

I have written a very short program, called lpt1init.exe, which clears the
DVK bits, PTT and CW keying and asserts the strobe line.  Running
this before starting CT and turning on the SCKII keeps the SCKII
from going crazy.  If anyone would like either the trivial source code,
or the lpt1init.exe program, let me know.

On some computers, the SCKII is unusable with CT without a
workaround like this.


Mark, KD4D

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