Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!uunet!verifone!jimmy_t
From: jimmy_t@verifone.com
Newsgroups: comp.os.msdos.programmer
Subject: Re: Printing Graphics files via LPT1:
Message-ID: <2498.278cc4a0@verifone.com>
Date: 12 Jan 91 03:13:04 GMT
References: <8280@emcard.UUCP>
Organization: VeriFone Inc., Honolulu HI
Lines: 60

In article <8280@emcard.UUCP>, mat@emcard.UUCP (W Mat Waites) writes:

> I'm trying to print bitmaps files to a Laserjet via LPT1: and the image
> gets all trashed. I'm wondering if LPT1: is only passing 7 bits, playing
> with what it thinks are tabs, etc. I know the file is good because I can
> print it to a Laserjet from a Unix system (serial interface) and it works
> fine.
> 
> How can I get raw data through the parallel port?
> 

If you are opening the LPT in a program as a DOS file, even if you tell DOS
you want binary mode it may not give it to you.
Here is the Microsoft C code I use to get around this problem.
After I do a normal open of the file in binary mode, I call this
routine with the handle returned by the open function:

/****************************************************************************
			  Set Binary Mode
*****************************************************************************/
void set_binary_mode (int target_handle)
{
	int hand;
	union REGS r;
 
	/* get device info */
	memset(&r, 0, sizeof(r));
	r.h.ah = 0x44;
	r.h.al = 0x00;
	r.x.bx = target_handle;
	r.x.dx = 0;
	(void) int86(0x21, &r, &r);
 
	/* Check to see if DOS actually put device in character mode
		despite our request for binary mode.  This is rumored
		to happen if you open a character device like LPT1:
		*/
 
	if (
		 (r.h.dl & 0x80)  /* is it a character device? */
	&& !(r.h.dl & 0x20) 	/* in "cooked" mode */
		) {
		memset(&r, 0, sizeof(r));
		r.h.ah = 0x44;
		r.h.al = 0x01;
		r.x.bx = target_handle;
		r.h.dh = 0x00;
		r.h.dl |= 0x20;  /* set raw mode */
		(void) int86(0x21, &r, &r);
		}
}


-- 
+------------------------------------+--------------------------------------+
|  James H. Thompson                 |   jimmy_t@verifone.com    (Internet) |
|  VeriFone Inc.                     |   uunet!verifone!jimmy_t  (UUCP)     |
|  100 Kahelu Avenue                 |   808-623-2911            (Phone)    |
|  Mililani, HI 96789                |                                      |
+------------------------------------+--------------------------------------+