Your Turn

The sequence has played. The panels have faded back to normal. Now the screen waits. The player presses a number key and the game checks it against the expected colour — right or wrong, instantly. This is where Colour Flood becomes interactive.

Player Input

Add these lines after the sequence playback code:

 110 PRINT AT 19,7; INK 2; BRIGHT 1;"Your turn!              "
 112 FOR i=1 TO LEN s$
 114 IF INKEY$<>"" THEN GO TO 114
 116 IF INKEY$="" THEN GO TO 116
 118 LET k$=INKEY$
 120 IF k$<"1" OR k$>"4" THEN GO TO 114
 122 LET c=VAL k$
 124 LET e=VAL s$(i TO i)
 126 IF c<>e THEN GO TO 200
 128 GO SUB 500
 130 PAUSE 6
 132 GO SUB 400
 134 NEXT i

Type RUN. Watch the sequence play (still hardcoded as “132”), then repeat it: press 1, then 3, then 2.

Press 1 and the blue panel flashes bright, the same low tone plays — it mirrors what the computer showed you. Press 3 and green floods the screen. Press 2 and red lights up with a mid-range note. Each correct keypress feels right because it looks and sounds exactly like the original playback.

Press the wrong key and the game jumps to line 200 — the game over handler you will build in Unit 7.

How the Check Works

The FOR loop runs through the sequence string one character at a time, just like the playback loop. But instead of flashing automatically, it waits for the player:

• Line 114 — wait for any held key to be released. This prevents one long press from counting as multiple inputs.
• Line 116 — wait for a new keypress. The loop spins here until a key goes down.
• Line 118 — capture the key in k$.
• Line 120 — ignore anything outside “1” to “4”. If the player presses “7” or “q”, go back to waiting.
• Line 122 — convert the key to a number with VAL k$.
• Line 124 — read the expected colour from the sequence string with VAL s$(i TO i).
• Line 126 — compare. If they do not match, jump to the game over code. If they match, flash the panel and continue to the next colour.

The Debounce Pattern

Lines 114-116 form a debounce pattern. Without them, a single keypress could register multiple times — the Spectrum checks INKEY$ thousands of times per second. “Wait for release, then wait for press” ensures each physical keypress counts exactly once.

Try This

• Change the sequence to s$="1234" and play through it. Does the feedback loop feel satisfying — press, flash, tone, next?
• Press the wrong key deliberately. The program tries to jump to line 200. Add 200 PRINT "Wrong!" temporarily so you can see the error path working.

What You’ve Learnt

• INKEY$ for game input — reads whatever key is currently held, returns "" if nothing is pressed
• Debounce — wait for release then press; stops one keypress counting twice
• String comparison — c<>e compares the player’s colour against the expected one
• Immediate feedback — correct keypresses flash the matching panel; wrong keypresses end the game