Hi Richard,

For the parallel port, use the INP() and OUT() commands.
To find your port addresses, invoke debug and type: d 40:0 <enter>

You'll get something like:

-d 40:0  <=== this is what you typed in at the debug prompt

0040:0000  F8 03 F8 02 E8 03 E8 02-BC 03 78 03 78 02 C0 9F
..........x.x...


You'll see that on my computer my port addresses are as follows:
        COM1 = 0x3F8
        COM2 = 0x2F8
        COM3 = 0x3E8
        COM4 = 0x2E8

        LPT1 = 0x3BC (base address)
        LPT2 = 0x378 (base address)
        LPT3 = 0x278 (base address)

      (you can't assume, for example, that LPT1 will
       always translate to a 0x3BC -- always check with
       debug on any machine you will use)



On the parallel port:
        Data register = base address
        Status register = base address + 1
        Control register = base address + 2





        ' This is *no*t code that should be executed in order, these are just code
snippets:

        ' Upon start-up, cache the control register into a global variable
       ControlByte = INP(ControlReg)

       ' Force parallel port data bus to OUTPUT mode
       ControlByte = (ControlByte And 223)
         OUT ControlReg, ControlByte

       ' Force parallel port data bus to INPUT mode
       ControlByte = (ControlByte Or 32)
         OUT ControlReg, ControlByte


         ' Read the parallel port's data bus
         DataByte = INP(DataReg)


         ' Write to the parallel port's data bus
         OUT DataReg, DataByte



May I ask a few questions?

1) Do you have to use QBASIC? I'm just curious why you want to do this in
QBASIC. Would you consider another language?

2) Do you have a bidirectional parallel port installed on the computer? If
so, do you know it's address?

3) Could you give more details on exactly what you are trying to accomplish
(the overall picture)?

Hope this gives you a start, but please chime in to provide some more
specifics since there's more than one way to skin a cat. As for the serial
port, there should be QBASIC documentation for this.


Best regards,

Ken Pergola




-----Original Message-----
From: pic microcontroller discussion list
[mailto:PICLIST@MITVMA.MIT.EDU]On Behalf Of Richard Graziano
Sent: Tuesday, September 16, 2003 11:03 PM
To: PICLIST@MITVMA.MIT.EDU
Subject: [EE] QBASIC QUESTION


Does anyone know how to write a QBASIC command to transfer a byte or
multiple sequence of bytes to the parallel port of a PC,  and also to read a
byte or multiple sequence of bytes from the parallel port?  Also, the same
question applies to the serial port.  I would appreciate any information on
this software question.

Regards,
Richard

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