I'm
having a parallel port download problem on Win NT
This is a well-known problem that has
been around for quite some time with
no resolution. Basically, Windows NT 4.0 ignores Parallel
Port handshake and downloads without regard for the emulator
asserting the Parallel Port's "Busy" line.
The following procedure is a workaround:
This has been tested on Windows NT 4.0
with Service Pack 1 (Build 1381)
installed, logged in as Administrator, with 16-bit SourceGate
II v3.1.0.Beta16. Any Parallel Port mode (AT, PS/2, EPP,
ECP) is acceptable.
This has *not* been tested under other builds of Windows,
logged in as
other (ordinary) users, nor with other versions of SourceGate,
notably not any 32-bit version of SourceGate.
The problem we are trying to resolve
is twofold: Without a printer driver
attached to the parallel port, NT will not handshake properly.
With a
printer driver attached to the parallel port, NT insists
on spooling
anything sent to the parallel port (even when we tell
it quite firmly not
to), resulting in truncated downloads.
Procedure:
1) Make sure no printer drivers are attached
to the parallel port
SourceGate is going to use for downloading (for the purposes
of this writeup, we will assume that this is LPT1). Go
to "Start|Settings|Printers" and right-click
on all the printer icons shown in this dialog. Select
"Properties" and
then the "Ports" tab and make sure "LPT1:"
is *not* checked.
2) Install the "Generic/Text Only"
printer driver and attach it to LPT1. Accept all default
settings for this printer driver. If the "Generic/Text
Only" printer driver is already installed, go to
"Start|Settings|Printers" and right-click on
the "Generic/Text Only" printer icon. Select
"Properties" and then the "Ports"
tab and click on the checkbox for "LPT1:". Close
the dialog via the "OK" button.
3) Start SourceGate. Download a small
file via the Parallel Port. A "small" file is
one smaller than 3.5K in size. A file containing the following
two lines will do:
%276E01058585858585858585858585858585858
%0781010
The purpose of this download is to "grease
the skids" and get something
from SourceGate, through NT, through the Parallel Port,
and down to emulator memory. A file smaller than 3.5K
appears to download correctly without running afoul of
the spooling system. Once SourceGate says the download
is complete, close SourceGate's download status dialog.
3a) Double-check: Go to "Start|Settings|Printers"
and double-click on the
"Generic/Text Only" printer icon. The print
job status dialog that appears
should be empty. If it is not empty, right-click on the
print job and select "Cancel". Note that it
might take several minutes for the print job to disappear
from the dialog. You *must* wait for the print job to
be purged and disappear from the dialog before proceeding.
(This is why the initial download file should be "small".
If the initial download file is too big, it will not download
completely through the spooling system before the emulator
believes the download has ended, and the tail end of it
will be
stuck in the spooler. After 90 seconds, NT will timeout
and let you know
there is something stuck in the print spooler. If this
happens, select
"Cancel" from the timeout dialog to make the
stuck download go away.)
4) Go to "Start|Settings|Printers"
and right-click on the "Generic/Text
Only" printer icon. Select "Properties"
and then the "Ports" tab and attach
the printer driver to something other than "LPT1:"
("FILE:" will do). Close
the dialog via the "OK" button.
SourceGate should now be able to download
properly through the Parallel
Port until the next time the NT box is rebooted (as long
as LPT1 is not used for ordinary printing). After the
NT box is rebooted, this procedure will have
to be followed again to make the Parallel Port work with
SourceGate. Exiting and restarting SourceGate does not
appear to have any effect on the ability to use the Parallel
Port after this procedure is followed.
For whatever reason, once the "Generic/Text
Only" printer driver has been
attached to the Parallel Port, used by SourceGate, and
then detached, NT
will handshake properly and not use the spooling system
to handle Parallel
Port downloads.
Error indications:
Step 1) If this step is nor performed,
SourceGate will get "CHECKSUM ERROR"s, "INVALID
HEX RECORD" errors, or other errors as the Parallel
Port
handshake is not observed and character overruns occur.
Or, the printer
driver that is attached to LPT1 will intercept and mangle
the download, and
possibly spool it. If the download is spooled, after 90
seconds a print
spooler error will occur.
Step 2) If the "Generic/Text Only"
printer driver is not used, the driver that *is* used
will mangle the bytes being sent to the emulator. The
"Generic/Text Only" driver will (usually) not
try to interpret the bytes sent to it, but will instead
simply pass them through unchanged.
Step 3) If this step is not performed,
NT will not put everything into place that makes the handshake
occur. The bytes sent out the Parallel Port to the emulator
*must* come from SourceGate, and not from some other source
(for example, the "Generic/Text Only" printer
driver's "Print Test Page" function won't do!).
Step 3a) If something becomes stuck in
the print spooler, SourceGate will
not be allowed access to the Parallel Port until the stuck
download is cleared.
Step 4) If the "Generic/Text Only"
printer driver is not disconnected from the Parallel Port,
SourceGate Parallel Port downloads will appear to occur
much more quickly as usual as they are spooled, but the
emulator will not receive the complete download. After
90 seconds, a print spooler error will
occur, and the stuck download will need to be canceled.
Products