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Real-Time Clock

Real-Time Clock. Module M19.4 Section 14.1 (p.415). Real-time Clock. Time of Day options using INT 1AH. 32-bit counter at address 0040:006C - 0040:006F Counter increments 18.2 times per second. Each increment is called a tick. Interrupt Vector Table. INT 1CH Timer Tick Offset: $070.

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Real-Time Clock

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  1. Real-Time Clock Module M19.4 Section 14.1 (p.415)

  2. Real-time Clock Time of Day options using INT 1AH 32-bit counter at address 0040:006C - 0040:006F Counter increments 18.2 times per second. Each increment is called a tick.

  3. Interrupt Vector Table INT 1CH Timer Tick Offset: $070

  4. The Timer Tick hardware interrupt increments the 32-bit counter and then calls INT 1CH. The software interrupt routine just returns using the IRET instruction. Therefore, INT 1CH is called 18.2 times per second.

  5. Interrupt Vector Table INT 1CH Timer Tick Offset: $070 You can replace the IP and CS values at 0000:0070 with the address of your routine.

  6. Real-time clock interrupt service routine algorithm

  7. Setting the interrupt vectorusing an INT 21H DOS call push ds push cs pop ds mov dx,offset intser mov al,1Ch mov ah,25h int 21h pop ds

  8. Storing the time 10:24:37in the keyboard buffer

  9. Real-time clock interrupt service routine algorithm

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