Category : C Source Code
Archive   : CBIBLE.ZIP
Filename : OUTPORTB.C

 
Output of file : OUTPORTB.C contained in archive : CBIBLE.ZIP
/* outportb.c --- p 525 */
#include
#include
#define TIMER_FREQ 1193180L /* Timer freq = 1.19 MHz */
#define TIMER_COUNT 0x42 /* 8253 timer -- count */
#define TIMER_MODE 0x43 /* 8253 timer control port */
#define TIMER_OSC 0xb6 /*To use timer as oscillator */
#define OUT_8255 0x61 /* 8255 PPI output port adrs */
#define SPKRON 3 /* Bit 0 = control spkr by timer*/
/* Bit 1 = speaker on/off */
main()
{
unsigned freq, status, ratio, part_ratio;
char input[81];
cprintf("Enter frequency in Hz (between 100 and 15000):");
cscanf("%hu", &freq);
/* First read and save status of the 8255 chip */
status = inportb (OUT_8255);
/* Put timer in oscillator mode */
outportb (TIMER_MODE, TIMER_OSC);
ratio = (unsigned)(TIMER_FREQ/freq);
part_ratio = ratio & 0xff; /* low byte of ratio */
outportb(TIMER_COUNT, part_ratio);
part_ratio = (ratio >> 8) & 0xff; /* high byte */
outportb(TIMER_COUNT, part_ratio);
/* Finally turn on speaker */
outportb (OUT_8255, (status : SPKRON));
/* Ask user to indicate when to stop the
* annoying tone... */
cprintf("\nHit return to exit:");
cgets(input);
/* Now turn off speaker */
status = inportb (OUT_8255); /* get current status */
/* Turn speaker off */
outportb (OUT_8255, (status & ~SPKRON));
}

  3 Responses to “Category : C Source Code
Archive   : CBIBLE.ZIP
Filename : OUTPORTB.C
”

  1. Daniel says:
    January 27, 2013 at 3:59 pm

    Very nice! Thank you for this wonderful archive. I wonder why I found it only now. Long live the BBS file archives!

  2. Joshie says:
    March 18, 2014 at 4:57 pm

    This is so awesome! 😀 I’d be cool if you could download an entire archive of this at once, though.

  3. DiskingRound says:
    January 14, 2015 at 10:57 pm

    But one thing that puzzles me is the “mtswslnkmcjklsdlsbdmMICROSOFT” string. There is an article about it here. It is definitely worth a read: http://www.os2museum.com/wp/mtswslnk/