Label Maker

Label Maker is a utility that prints centered cassette tape labels on a full-size printer using LPRINT statements. The program collects up to four lines of text (each capped at 32 characters), centers each line using a TAB calculation of 16 minus half the string length, previews the layout on screen, then prints the requested number of copies with blank lines to simulate a label gap. Lines 200–290 form a self-contained documentation section that describes setup instructions, compatible printer interfaces, and label suppliers, which the user reaches by breaking out of the run-time flow. A POKE to system variable 23617 and repeated POKEs to 23692 (the scroll counter) manage display behavior during the informational section.

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Program Structure

The program is divided into two logically separate sections. Lines 5–180 form the operational label-making loop, while lines 200–350 constitute a standalone documentation and setup guide that is only reached by manually breaking program execution and entering GO TO 200. This split means a normal run never visits the instructions block.

Line Range	Purpose
5	Initialization: BORDER, PAPER, INK, CLS, POKE 23617
10–44	Input four label lines with length validation and screen preview
50–56	Confirmation prompt with FLASH and keypress loop
100–132	LPRINT loop for requested number of copies
140–154	“More copies?” and “Another title?” decision trees
160–180	Exit messages and STOP statements
200–290	Documentation / instructions (manual entry only)
300	SAVE with LINE autorun, then VERIFY
350	REM placeholder for disc SAVE command

Input and Validation

Each of the four label lines (a$, b$, c$, d$) is collected with INPUT … LINE, which accepts the full string including spaces without treating commas or colons as delimiters. After each INPUT, the length is tested against 32 characters — the practical maximum for a centered label on a 32-column-wide field — and control loops back to re-prompt if exceeded.

Line 30 embeds raw character codes \{17}\{3}\{17}\{2}\{17}\{7} inside the INPUT prompt string. These are INK and PAPER color-change control characters (17 = INK, 3 = magenta; 17 = PAPER, 2 = red; 17 = INK, 7 = white), adding a colored prompt for the third input field.

Centering Algorithm

All four lines are centered on both screen and printer using the same formula:

• TAB 16-(LEN x$/2)

This assumes a 32-character-wide output medium (half = 16) and works correctly for even-length strings. For odd-length strings, integer division truncates the result, shifting the text one column to the right of true center — a minor cosmetic quirk inherent to integer BASIC arithmetic.

Keypress Handling and Confirmation Loop

Lines 50–56 implement a FLASH confirmation prompt. The idiom used is a tight INKEY$="" spin-loop at line 52 to wait for any key, followed by explicit checks for "n"/"N" and "y"/"Y". If neither matches, control returns to line 52. This same pattern is repeated at lines 140–154 for the “More copies?” and “Another title?” prompts, with PAUSE 5 calls inserted to debounce the keypress and prevent the same keystroke from immediately triggering the next prompt.

LPRINT Output

The printing section (lines 120–132) mirrors the screen layout exactly. Five blank LPRINT statements between the body lines and the bottom line simulate the blank space in the middle of a cassette label. Two additional blank lines after the bottom line provide inter-label spacing for continuous form-feed label stock.

System Variable POKEs

Two system variable POKEs are used:

• POKE 23617,236 at line 5 — address 23617 is BORDCR, setting the border color and also influencing the lower screen area’s paper/ink attributes.
• POKE 23692,255 at lines 240, 260, 270 — address 23692 is SCR_CT, the scroll counter. Setting it to 255 suppresses the “scroll?” prompt during the lengthy documentation printout, allowing text to scroll freely without user intervention.

Documentation Section (Lines 200–290)

Lines 200–290 form a self-contained instruction manual displayed entirely in BASIC PRINT statements. It describes how to load a printer interface driver before this program, how to chain-save both programs to tape, and where to purchase form-feed cassette labels. Line 283 uses an overprint trick to draw an underline: a forward loop prints CHR$ 8 (backspace) five times, then uses OVER 1 to print CHR$ 95 (underscore) over existing text, simulating a formatting effect for the word “BREAK”.

SAVE and Disc Lines

Line 300 saves the program with LINE 200 and immediately verifies it, then jumps to 200 to redisplay the instructions. Line 350 is a REM statement containing a commented-out disc SAVE command (OUT 244,1:MOVE "Labels.BAS",200), suggesting AERCO disc interface syntax, preserved as a reminder for users with that hardware.

Notable Anomalies

• Lines 170 and 180 are redundant STOP statements that are never reached in any normal execution path.
• The INPUT "" at lines 240 and 275 acts as a “press ENTER to continue” pause alongside PAUSE 0, providing a belt-and-suspenders approach to halting output.
• The variable X is reused across multiple unrelated FOR loops in the documentation section (lines 200, 210, 283) without conflict since each loop completes before the next begins.