112 Section 8: Programming BasicsThe 000 Instruction and Program Line 000

Whenever you run the program now stored in program memory, the calculator executes the instruction in line 008 after executing the seven instructions you keyed in. This i000 instruction — as its name implies — tells the calculator to “go to” program line 000 and execute the instruction in that line. Although line 000 does not contain a regular instruction, it does contain a “hidden” instruction that tells the calculator to halt program execution. Thus, after each time the program is run, the calculator automatically goes to program line 000 and halts, ready for you to key in new data and run the program again. (The calculator is also automatically set to program line 000 when you press fsto set the calculator from Program mode to Run mode or when fCLEARÎis pressed in run mode.)

The i000 instruction was already stored in line 008 — in fact, in all program lines — before you keyed in the program. If no instructions have been keyed into program memory, if Continuous Memory is reset, or if fCLEARÎis pressed (in Program mode), the instruction i000 is automatically stored in program lines 001 through 008. As you key each instruction into program memory, it replaces the i000 instruction in that program line.

If your program should consist of exactly eight instructions, there would be no i000 instructions remaining at the end of program memory. Nevertheless, after such a program is executed the calculator automatically returns to program line 000 and halts, just as if there were a i000 instruction following the program.

If you key in more than eight instructions, program memory automatically expands to accommodate the additional instructions.

Expanding Program Memory

If no instructions have been keyed into program memory, if Continuous Memory has been reset, or if fCLEARÎhas been pressed (in Program mode), program memory consists of 8 program lines, and there are 20 storage registers available for storage of data.

File name: hp 12c pt_user's guide_English_HDPMF123E27

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Printed Date: 2005/8/1

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