Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!tut.cis.ohio-state.edu!rutgers!apple!oliveb!pyramid!ctnews!starfish!cdold
From: cdold@starfish.Convergent.COM (Clarence Dold)
Newsgroups: comp.sys.ibm.pc
Subject: Re: Determining if a printer is available
Message-ID: <979@starfish.Convergent.COM>
Date: 29 Mar 89 19:12:24 GMT
References: <42@datcon.UUCP>
Organization: Convergent Technologies, San Jose, CA
Lines: 79

From article <42@datcon.UUCP>, by sar@datcon.UUCP (Simon A Reap):
> In article <7730@pyr.gatech.EDU> curci@stat.fsu.edu (Ray Curci (scri)) writes:
>>In article <2165@pembina.UUCP> lake@alberta.UUCP (Robert Lake) writes:
>>>I am trying to determine if a line printer is attached to my PC.  I am

> But beware: as far as I can see, even hacking as assembler, there's no
> way to differentiate between an on-line paper-full printer all ready to
> roll out your pearls, and a printer that's just powered OFF :-) (sure

On my AT-Clone, with an Epson RX-80, I find that status truly boils down
to three bits: NOT_BUSY, PAPER_OUT, and IOERR
We could say that there are six states for the printer:
1- No Printer I/O Card				0x00
2- Printer not connected			0x30
3- Printer Off					0x98
4- Printer Offline				0x18
5- Printer Out of Paper				0xb0
	Offline and out of paper		0x38
6- Online and ready.				0x90
In each case, BIOS INT 0x17, ah=2 returns	^

I didn't bother with checking if BUSY was really BUSY with a print task,
since we were talking about a 'pre-print' on-line check.
I also don't know how shared printer usage affects the return.  I suspect
that it would give 'off line' in either case.

/* for QuickC, CADold cdold@tsdold.Convergent.COM */

#include <stdio.h>
#include <dos.h>
union   REGS    regs;

#define PRT_BIOS 0x17
#define PRT_STAT 0x02
#define PRT_PORT 0x00
#define NOTBUSY 0x80
#define PAPER_OUT 0x20
#define IOERR 0x08

main()
 {

  int prt_stat, retstat=1;
  regs.h.ah = PRT_STAT;
  regs.x.dx = PRT_PORT;
  int86(PRT_BIOS, &regs, &regs);
  prt_stat=regs.h.ah;
  printf("Port Status: %x\n", prt_stat );

  switch(prt_stat & ( NOTBUSY | PAPER_OUT | IOERR) ) {
  /* masking off unintelligent bits */
	case 0x00:
		printf("No Printer Port\n");
		break;
	case 0x08:
		printf("Printer is Offline\n");
		break;
	case 0x20:
		printf("Printer is not connected\n");
		break;
	case 0x28:
	case 0xa0:
		printf("Printer is Out of Paper\n");
		break;
	case 0x80:
		printf("Printer is Online and Ready\n");
		retstat=0;
		break;
	case 0x88:
		printf("Printer is Turned Off\n");
		break;
	}
void exit(retstat);
} /* end of main */
-- 
---
Clarence A Dold - cdold@starfish.Convergent.COM		(408) 434-5293
		...pyramid!ctnews!tsdold!dold
		P.O.Box 6685, San Jose, CA 95150-6685	MS#10-007