Morse

This program is a Morse code trainer that teaches, transmits, and tests the user’s knowledge of the international Morse alphabet. It stores all 26 letter codes as a single DATA string at line 1000, using “.” for dots and “-” for dashes, then plays them audibly via BEEP with dashes sounding three times longer than dots (BEEP speed vs. BEEP speed/3). Three modes are offered: an alphabet review that steps through A–Z one letter at a time with visual and audio output, a message sender that encodes arbitrary text input character by character, and a multiple-choice test that randomly selects letters using RND and scores the user’s typed responses. The menu uses PRINT OVER 1 with underscore characters to animate underlines beneath the menu options as a decorative effect.

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Program Analysis

Program Structure

The program is organized into four distinct functional blocks, entered via GO TO from a central menu at line 2000:

1. Menu / initialization — lines 2000–2110: resets score, sets speed, draws the menu, and polls INKEY$ in a tight loop.
2. Alphabet review — lines 8–70: iterates FOR a=1 TO 26, reads each Morse code string, prints and plays it, and waits for a keypress before advancing.
3. Send message — lines 90–320: accepts an INPUT string, encodes each character by scanning the DATA list, and plays the corresponding Morse tones.
4. Test — lines 399–840: prompts for a question count, randomly selects letters via RND, plays their Morse tones, and scores typed answers.

DATA Layout and Access

All 26 Morse code strings are stored in a single DATA statement at line 1000, ordered A–Z. Each routine calls RESTORE before reading so the data pointer is always reset to the beginning. The message-sender at line 130 locates a letter by iterating FOR e=1 TO 26 and comparing e=d-64 (where d is the ASCII code of the input character), then jumps to line 300. However, line 300 does not exist — the jump target is 301, which is a well-known technique relying on the interpreter finding the next available line.

Morse Timing

The speed variable is initialized at LET speed=.2 (line 2005). Dashes are played as BEEP speed,20 and dots as BEEP speed/3,20, correctly maintaining the standard 3:1 dash-to-dot duration ratio. Both use the same pitch (note value 20). The speed value is never exposed to user adjustment in the menu, though the variable name suggests it was intended to be configurable.

Key BASIC Idioms

• PAUSE 0 at line 56 and 800 halts execution until any key is pressed — the standard Sinclair-family keypress-wait idiom.
• RESTORE is called at the top of each mode to reset the DATA pointer, since all three modes share the same single DATA line.
• Menu animation at lines 2091–2096 uses PRINT OVER 1 with underscore characters to draw and redraw underlines beneath menu items, creating a simple visual effect without clearing the screen.
• PRINT OVER 1;AT 3,10;"__________" at line 2012 underlines the title “MORSE CODE” using OVER mode so it overlays without erasing the text above.

Test Mode Logic

The test mode at line 400 randomly selects a Morse code string by reading past INT(RND*26)+1 entries from the DATA list (FOR a=1 TO INT(RND*26)+1 / READ a$ / NEXT a). After playing the tones, the expected answer is computed as LET ans=a+63 — since after the loop a has been incremented one past the selected index by NEXT a, this actually computes CHR$(selected_index + 64), which is the correct uppercase letter. The comparison at line 560 uses CODE n$=ans, meaning only exact uppercase or lowercase matching is accepted depending on the shift state.

Bugs and Anomalies

Line	Issue
2060	The instruction message contains a typographical run-on: "caps shift isin the ON ERR" — the word “is” and “in” are merged, and ON ERR (the { keyword) appears where the word “CAPS LOCK” was probably intended.
840	PRINT 300 appears to be a stray line; it likely should be PAUSE 300 to give the player time to read the score before returning to the menu.
121	IF d=32 THEN NEXT l skips spaces in the message, which works correctly but relies on jumping to the NEXT statement directly — a somewhat unconventional flow-control approach.
2087	GO TO 99 targets a non-existent line; the interpreter will proceed to line 100, the start of the Send Message section — intentional and functional.
560	Case sensitivity: CODE n$=ans compares the raw character code against the uppercase letter code, so lowercase input will fail. The menu warning about caps lock (garbled as it is) addresses this.