108 Section 8: Programming Basics

Program Memory

Keystrokes entered into the calculator in Program mode are stored in program memory. Each digit, decimal point, or function key is called an instruction and is stored in one line of program memory — usually referred to simply as a program line. Keystroke sequences beginning with the f, g, ?, :, and i prefix keys are considered to comprise a complete instruction and are stored in only one program line.

When a program is run, each instruction in program memory is executed — that is, the keystroke in that program line is performed, just as if you were pressing the key manually — beginning with the current line in program memory and proceeding sequentially with the higher-numbered program lines.

Whenever the calculator is in Program mode (that is, whenever the PRGM status indicator in the display is lit), the display shows information about the program line to which the calculator is currently set. At the left of the display is the number of the program line within program memory. The remaining digits in the display comprise a code that indicates what instruction has been stored in that program line. No code is shown for program line 000, since no regular instruction is stored there.

Identifying Instructions in Program Lines

Each key on the hp 12c platinum keyboard — except for the digit keys 0 through 9 — is identified by a two-digit “keycode” that corresponds to the key’s position on the keyboard. The first digit in the keycode is the number of the key row, counting from row 1 at the top; the second digit is the number of the key in that row, counting from 1 for the first key in the row through 9 for the ninth key in the row and 0 for the tenth key in the row. The keycode for each digit key is simply the digit on the key. Thus, when you keyed the instruction b into program memory, the calculator displays a line number and a keycode

004, 25

This indicates that the key for the instruction in program line 004 is in the second row on the keyboard and is the fifth key in that row: the bkey. When you keyed the instruction +into program memory, the calculator displays a line number and keycode as

007, 40

This indicates that the key for the instruction in program line 007 is in the fourth row on the keyboard and is the tenth key in that row: the +key. When you keyed the digit 5 into program memory, the keycode displayed was only the digit 5.

File name: hp 12c pt_user's guide_English_HDPMF123E27

Page: 108 of 275

Printed Date: 2005/8/1

Dimension: 14.8 cm x 21 cm

Page 108
Image 108
HP 12C Financial 12C manual Program Memory, Identifying Instructions in Program Lines