P-port 101 was Re: troubleshooting help

Rick,

The parallel port is actually THREE 8 bit "ports"; Data, Status, and
Control. The Data byte is at the "base" address, in your case, 888.
The Status byte is at base+1(only 5 bits are available to use); and
the Control byte(only 4 bits available*) is at base+2.

Out 888 is for the DATA byte of the "first" (lpt1) p-port. This is
connected to pins 2-9 on the db25 connector. The CONTROL port is at
890; it controls (pun intended<G>) pins 1,14,16,17. The status port
is at 889, and receives the inputs at pins 10,11,12,13,15.

Some of the bits on the status and control port are inverted, due to
the original implementation of the Centronics printer standard by IBM.

There are also two other base addressses commonly used for "printer"
p-ports on the IBM pc. Lpt2 at 278h, which is 632 decimal. And Lpt3
at 3BCh,which is 956 decimal. You can use the out command with either
Hex or decimal numbers.

Jan Axelsons P-port complete is a VERY good book on the subject. Read
about it, and the p-port, at:

http://www.lvr.com

Hope this helps.

Ballendo

P.S. This is a very short explanation of a much longer subject, with
details left out...

* The control byte has a 5th bit "available" to set up the p-port.
All references above are for the "standard" p-port, sometimes called
the SPP in your bios setup. The EPP and ECP are "updates" of the p-
port, with additional features, registers, and addresses.

--- In CAD_CAM_EDM_DRO@y..., "Rick Miller" <apollo@a...> wrote:
> Hello!
> I just finished wiring up my 3-axis controller, and I'm having
trouble <snip>
> I tried to send step signals "manually" by using the OUT 888, [x]
command from qbasic, without having any luck. I'm wondering if anyone
knows what parameters (if any) from the basic OUT command would send
a signal to either pin 1, 14, or 16; this would allow me to at least
test the relay for function.
>
> If there are any other simple ways to test the parallel port,
I'd like to know... also, if anyone has any other troubleshooting
suggestions, I'd appreciate them. I did put my voltmeter across the
pins on the parallel port while running a loop of the OUT command;
there was no difference on the meter, it stayed at +4.5VDC the whole
time; perhaps the signal pulse is too short for my digital voltmeter
to read properly?
>
> Thanks in advance for any suggestions,
> Rick
>
>
> [Non-text portions of this message have been removed]