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Elite on the BBC Micro

Keyboard: DKS1 [Elite-A, Flight]

Name: DKS1 [Show more] Type: Subroutine Category: Keyboard Summary: Scan the keyboard for a flight key Deep dive: The key logger
Context: See this subroutine in context in the source code References: This subroutine is called as follows: * DK4 calls DKS1 * DKJ1 calls DKS1 * DOKEY calls DKS1 * b_14 calls entry point b_pressed

Scan the keyboard for the flight key given in register Y, where Y is the offset into the KYTB table above (so we can scan for Space by setting Y to 2, for example). If the key is pressed, set the corresponding byte in the key logger at KL to &FF. Arguments: Y The offset into the KYTB table above of the key that we want to scan on the keyboard Other entry points: b_pressed Store &FF in the Y-th byte of the key logger at KL, to indicate that key is being pressed
.DKS1 \ --- Mod: Code added for Elite-A: --------------------> LDA BSTK \ If BTSK is negative, then the Delta 14b joystick is BMI b_14 \ configured, so jump to b_14 to check the Delta 14b \ joystick buttons \ --- End of added code -------------------------------> LDX KYTB,Y \ Get the internal key number from the Y-th byte of the \ KYTB table above JSR DKS4 \ Call DKS4, which will set A and X to a negative value \ if the key is being pressed \ --- Mod: Original Acornsoft code removed: -----------> \ BPL DKS2-1 \ The key is not being pressed, so return from the \ \ subroutine (as DKS2-1 contains an RTS) \ --- And replaced by: --------------------------------> BPL b_quit \ The key is not being pressed, so return from the \ subroutine (as b_quit contains an RTS) .b_pressed \ --- End of replacement ------------------------------> LDA #&FF \ Store &FF in the Y-th byte of the key logger at KL STA KL,Y \ --- Mod: Code added for Elite-A: --------------------> .b_quit \ --- End of added code -------------------------------> RTS \ Return from the subroutine