Programming

16.1Program mode and how lines are recorded#

Shift R/S turns PRGM mode on or off. In PRGM mode keys are not executed; they are recorded as numbered program lines. The display shows the current line and the next line, for example 01▸LBL "CIRC". Line 00 is a header showing the program size, and .END. marks the end of memory. All programs share one memory.

Numbers are recorded as typed. Two numbers in a row need ENTER between them. Press ← to delete the current line and ▲ / ▼ to move through the program. Shift ▲ and shift ▼ (BST and SST) also step through lines.

Example 16.1

Record and read a program

1. Turn on PRGM mode and record a label, then x squared, then pi, then multiply and return.

   ⇧PRGMR/S⇧PGM.FCN3Σ+⇧ALPHAENTERΣ+√x1/xLOGLNΣ+Σ+√xENTER⇧x²√x⇧πR↓×⇧PGM.FCN31/x

   

2. Press EXIT to close the menu, then up twice to move back through the lines.

   EXIT▲▲

16.2The PGM.FCN menu#

Shift 3 opens PGM.FCN, the program functions, over three pages.

16.3Write and run a program#

A global label has a name such as "CIRC", typed in ALPHA. Run it with XEQ and the name, or press XEQ and choose it from the menu. A program continues until RTN. Local labels are two-digit numbers used inside a program.

Example 16.2

Circle area program

$$A=\pi r^{2}$$

1. Record CIRC: label, square, pi, multiply, return.

   ⇧PRGMR/S⇧PGM.FCN3Σ+⇧ALPHAENTERΣ+√x1/xLOGLNΣ+Σ+√xENTER⇧x²√x⇧πR↓×⇧PGM.FCN31/x⇧PRGMR/SEXITEXIT

   

2. Run it with radius 5: XEQ, then the name.

   5XEQ⇧ALPHAENTERΣ+√x1/xLOGLNΣ+Σ+√xENTER

Example 16.3

Hypotenuse from two legs

1. Record HYP: square, swap, square, add, square root. (EXIT closes the PGM.FCN menu so that the square-root key is not read as a menu key.)

   ⇧PRGMR/S⇧PGM.FCN3Σ+⇧ALPHAENTER1/x√xXEQ√xLOG√xENTER⇧x²√xx⇄y⇧x²√x+EXIT√x⇧PGM.FCN31/x⇧PRGMR/SEXITEXIT

2. Enter 3 and 4 and run it.

   3ENTER4XEQ⇧ALPHAENTER1/x√xXEQ√xLOG√xENTER

Example 16.4

Choose the program from the XEQ menu

1. Record CIRC, then press XEQ and the first menu key.

   ⇧PRGMR/S⇧PGM.FCN3Σ+⇧ALPHAENTERΣ+√x1/xLOGLNΣ+Σ+√xENTER⇧x²√x⇧πR↓×⇧PGM.FCN31/x⇧PRGMR/SEXITEXIT5XEQΣ+

Example 16.5

Running from the CATALOG

1. Open CATALOG, PGM, and press the program name.

   ⇧PRGMR/S⇧PGM.FCN3Σ+⇧ALPHAENTERΣ+√x1/xLOGLNΣ+Σ+√xENTER⇧x²√x⇧πR↓×⇧PGM.FCN31/x⇧PRGMR/SEXITEXIT2⇧CATALOG+1/xΣ+

See also Record a keystroke programNamed programs with variables

16.4Loops with DSE and ISG#

DSE and ISG use a control number of the form $ccccc.fffii$: the counter, a final value and an increment. ISG adds the increment; DSE subtracts it. After the change, if the counter has passed the final value, the next program line is skipped. This is how a loop ends.

The program below sums the numbers from N down to 1. It stores N in register 00 and a running total in register 01.

1. LBL "SUMN"
2. STO 00
3. 0
4. STO 01
5. LBL 01
6. RCL 00
7. STO+ 01
8. DSE 00
9. GTO 01
10. RCL 01
11. RTN

Example 16.6

Sum 1 to 5

$$\sum_{k=1}^{5}k=15$$

1. Record SUMN, then run it with 5.

   ⇧PRGMR/S⇧PGM.FCN3Σ+⇧ALPHAENTERLN1/xLNLOG√xLOGLOGΣ+ENTERSTO000STO01⇧PGM.FCN3Σ+01RCL00STO+01⇧PGM.FCN3▼XEQ00⇧GTOXEQ01RCL01⇧PGM.FCN31/x⇧PRGMR/SEXITEXIT5XEQ⇧ALPHAENTERLN1/xLNLOG√xLOGLOGΣ+ENTER

Example 16.7

Sum 1 to 10

1. The same program with 10.

   ⇧PRGMR/S⇧PGM.FCN3Σ+⇧ALPHAENTERLN1/xLNLOG√xLOGLOGΣ+ENTERSTO000STO01⇧PGM.FCN3Σ+01RCL00STO+01⇧PGM.FCN3▼XEQ00⇧GTOXEQ01RCL01⇧PGM.FCN31/x⇧PRGMR/SEXITEXIT10XEQ⇧ALPHAENTERLN1/xLNLOG√xLOGLOGΣ+ENTER

16.5Decisions with tests#

A test line (such as X<0?) makes the next line run only if the test is true. If it is false, the next line is skipped. The test menus are X?0 and X?Y on PGM.FCN page 2. Each has six comparisons: =, ≠, <, >, ≤, ≥.

Example 16.8

Absolute value with a test

1. Record AV: if X < 0 then change its sign.

   ⇧PRGMR/S⇧PGM.FCN3Σ+⇧ALPHAENTERΣ+Σ+LNLNENTER⇧PGM.FCN3▼Σ+√x+/−⇧PGM.FCN31/x⇧PRGMR/SEXITEXIT

2. Try it on −4.

   4+/−XEQ⇧ALPHAENTERΣ+Σ+LNLNENTER

Example 16.9

Test from the keyboard

1. From the keyboard a test answers Yes or No: is 5 less than 3? (Y=5, X=3, X<Y? is the third key of X?Y).

   5ENTER3⇧PGM.FCN3▼1/x√x

16.6Subroutines and local labels#

XEQ with a two-digit number calls a local label in the same program; RTN returns to the line after the call. GTO with a label jumps without returning. GTO then . and three digits moves the pointer to a line number; GTO . . goes to the end.

Example 16.10

Call a local subroutine

1. Record SB: call 05, add 1, return; label 05 multiplies by 10.

   ⇧PRGMR/S⇧PGM.FCN3Σ+⇧ALPHAENTERLN1/xΣ+1/xENTERXEQ051+⇧PGM.FCN31/x⇧PGM.FCN3Σ+0510×⇧PGM.FCN31/x⇧PRGMR/SEXITEXIT

2. Run with 3: (3 × 10) + 1.

   3XEQ⇧ALPHAENTERLN1/xΣ+1/xENTER

16.7Ask for input and show results#

INPUT asks for a variable: the screen shows the name and its current value, for example R?0.0000. Type the value and press R/S to continue. VIEW shows name=value. AVIEW shows text from the ALPHA register. PROMPT shows the ALPHA text and stops; press R/S to continue.

Example 16.11

Ask for a radius

1. Record IN: INPUT R, then compute the circle area.

   ⇧PRGMR/S⇧PGM.FCN3Σ+⇧ALPHAENTER1/xLOGLOGΣ+ENTER⇧PGM.FCN3√x⇧ALPHAENTERLNΣ+ENTERRCL⇧ALPHAENTERLNΣ+ENTER⇧x²√x⇧πR↓×⇧PGM.FCN31/x⇧PRGMR/SEXITEXIT

2. Run it: the program stops and asks for R.

   XEQ⇧ALPHAENTER1/xLOGLOGΣ+ENTER

   

3. Type 2 and press R/S.

   2R/S

Example 16.12

Show a variable

1. Record VW: store 42 in Z and VIEW it.

   ⇧PRGMR/S⇧PGM.FCN3Σ+⇧ALPHAENTERLNLNXEQΣ+ENTER42STO⇧ALPHAENTERXEQLOGENTER⇧PGM.FCN3LOG⇧ALPHAENTERXEQLOGENTER⇧PGM.FCN31/x⇧PRGMR/SEXITEXIT

2. Run it.

   XEQ⇧ALPHAENTERLNLNXEQΣ+ENTER

Example 16.13

Prompt with a message

1. Record PR: type HELLO in ALPHA, then PROMPT, then 7.

   ⇧PRGMR/S⇧PGM.FCN3Σ+⇧ALPHAENTERLOG√xLNΣ+ENTER⇧ALPHAENTER1/x√xΣ+LN√x√x√x√xLOG1/xENTER⇧PGM.FCN3▼√x7⇧PRGMR/SEXITEXIT

2. Run it; it shows HELLO and waits.

   XEQ⇧ALPHAENTERLOG√xLNΣ+ENTER

   

3. Press R/S to continue.

   R/S

Example 16.14

Show text with AVIEW

1. Record AW: HELLO text then AVIEW.

   ⇧PRGMR/S⇧PGM.FCN3Σ+⇧ALPHAENTERΣ+Σ+XEQΣ+ENTER⇧ALPHAENTERLOG1/x√x1/xENTER⇧PGM.FCN3LN⇧PRGMR/SEXITEXITXEQ⇧ALPHAENTERΣ+Σ+XEQΣ+ENTER

16.8Flags in a program#

Example 16.15

Set a flag and branch on it

1. Record FL: set flag 01, then if it is set run the next line (100).

   ⇧PRGMR/S⇧PGM.FCN3Σ+⇧ALPHAENTER1/xΣ+√x√xENTER⇧FLAGS6Σ+01⇧FLAGS6√x01100⇧PRGMR/SEXITEXIT

2. Run it.

   XEQ⇧ALPHAENTER1/xΣ+√x√xENTER

16.9Stop, step and interrupt#

Press R/S in PRGM mode to record a STOP line. When it runs, the program stops there and R/S resumes it. Outside PRGM mode, shift ▼ (SST) runs one program line at a time. A program that loops forever stops itself with the message Interrupted after about a million steps.

Example 16.16

Stop and resume

1. Record ST: double X, stop, then add 3.

   ⇧PRGMR/S⇧PGM.FCN3Σ+⇧ALPHAENTERLN1/xLN√xENTER2×R/S3+⇧PRGMR/SEXITEXIT

2. Run it with 5. It stops with 10 in X.

   5XEQ⇧ALPHAENTERLN1/xLN√xENTER

   

3. Press R/S to resume: 13.

   R/S

Example 16.17

An endless loop is interrupted

1. Record IL: label 01 then GTO 01.

   ⇧PRGMR/S⇧PGM.FCN3Σ+⇧ALPHAENTER1/xLOG√x√xENTER⇧PGM.FCN3Σ+01⇧GTOXEQ01⇧PRGMR/SEXITEXIT

2. Run it.

   XEQ⇧ALPHAENTER1/xLOG√x√xENTER

16.10Delete a program#

Use CLP in the CLEAR menu (second key) and choose the label name. It removes that program up to the next global label. Deleting a single line in PRGM mode is done with ←.

Example 16.18

Delete a program by name

1. Record CIRC, then CLEAR, CLP and its name.

   ⇧PRGMR/S⇧PGM.FCN3Σ+⇧ALPHAENTERΣ+√x1/xLOGLNΣ+Σ+√xENTER⇧x²√x⇧πR↓×⇧PGM.FCN31/x⇧PRGMR/SEXITEXIT⇧CLEAR←1/xΣ+

2. Try to run it: the label is gone.

   EXIT5XEQ⇧ALPHAENTERΣ+√x1/xLOGLNΣ+Σ+√xENTER

16.11Read and paste a program listing#

The Data and programs sheet shows the program memory as a numbered listing with one instruction per line, for example:

• 01 LBL "CIRC"
• 02 X↑2
• 03 PI
• 04 ×
• 05 RTN

You can copy this text or paste a listing to replace the program memory. Lines it cannot read are reported so you can fix them.

See also Import and export programs