Hi,
on Sun, 30 Jan 2000 at 20:30:07 o'clock, Emre TOPTANCI wrote:
Quote
> I want to use parallel ports under pascal.
I assume, out of statistical considerations, that you are using Turbo
Pascal from Borland (or Borland Pascal). This is important, because
things such as hardware access are not part of the language, but of
the specific compiler.
Quote
> To use this device
> I think y will need pulses through specific pins of the port.
This is a little bit too unspecific. I assume that you need to set the
data bits. Most homebrew parallel port devices work this way, partially
because it is so easy to use from the programmer's point of view.
In a normal PC, the port addresses for the parallel port are these:
If you have 1 or 2 of them:
LPT1: $378
LPT2: $278
If you have more than 2 of them:
LPT1: $3BC
LPT2: $378
LPT3: $278
LPT4: $2BC
The parallel connector has (among others) 8 data lines, called D1
through D8, which are pins 2 through 9 on the connector (regardless
whether you have a 25-pin or a 36-pin connector - which is what you
normally have on the printer side). If you send a byte to the port,
the lines are set according to the bits of this byte. That is, if you
send the bit $27, pins D1, D2, D3 and D6 are positive, the others are
grounded.
So far, this is language independent. Accessing a port in Turbo Pascal
is easy; there is a so-called Port array, similar to the Mem array:
Port[$378] := $A5;
produces the following state of the lines:
D8 -> 10100101 <- D1
- Sebastian
