mirror of
https://github.com/JohnSnape/6502code.git
synced 2025-01-06 04:30:13 +00:00
Add files via upload
This commit is contained in:
parent
7dff84abb3
commit
c28a0bd5ac
38
source/new_bell.txt
Normal file
38
source/new_bell.txt
Normal file
@ -0,0 +1,38 @@
|
|||||||
|
1 * The standard Apple II "Air-raid" bell has
|
||||||
|
2 * been replaced with a gentler tone. Use it
|
||||||
|
3 * to give users some aural feedback that
|
||||||
|
4 * they are using a ProDOS program.
|
||||||
|
5 * The code for it follows.
|
||||||
|
6 *
|
||||||
|
7 SPKR EQU $C030 ;this clicks the speaker
|
||||||
|
8 *
|
||||||
|
8000: 00 9 LENGTH DS 1 ;duration of tone
|
||||||
|
10 *
|
||||||
|
11 * This is the wait routine from the Monitor ROM.
|
||||||
|
12 *
|
||||||
|
8001: 38 13 WAIT SEC
|
||||||
|
8002: 48 14 WAIT2 PHA
|
||||||
|
8003: E9 01 15 WAIT3 SBC #1
|
||||||
|
8005: D0 FC 16 BNE WAIT3
|
||||||
|
8007: 68 17 PLA
|
||||||
|
8008: E9 01 18 SBC #1
|
||||||
|
800A: D0 F6 19 BNE WAIT2
|
||||||
|
800C: 60 20 RTS
|
||||||
|
21 *
|
||||||
|
22 * Generate a nice little tone
|
||||||
|
23 * Exits with Z-flag set (BEQ) for branching
|
||||||
|
24 * Destroys the contents of the accumulator
|
||||||
|
25 *
|
||||||
|
800D: A9 20 26 BELL LDA #$20 ;duration of tone
|
||||||
|
800F: 8D 00 80 27 STA LENGTH
|
||||||
|
8012: A9 02 28 BELL1 LDA #$2 ;short delay...click
|
||||||
|
8014: 20 01 80 29 JSR WAIT
|
||||||
|
8017: 8D 30 C0 30 STA SPKR
|
||||||
|
801A: A9 20 31 LDA #$20 ;long delay...click
|
||||||
|
801C: 20 01 80 32 JSR WAIT
|
||||||
|
801F: 8D 30 C0 33 STA SPKR
|
||||||
|
8022: CE 00 80 34 DEC LENGTH
|
||||||
|
8025: D0 EB 35 BNE BELL1 ;repeat LENGTH times
|
||||||
|
8027: 60 36 RTS
|
||||||
|
|
||||||
|
--End assembly, 40 bytes, Errors: 0
|
Loading…
Reference in New Issue
Block a user