penguin86/pato-z80-home-computer
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This commit is contained in:
Daniele Verducci (ZenPenguin)
2021-01-01 17:50:52 +01:00
parent b1f9788772
commit df49f62d3d
3 changed files with 44 additions and 12 deletions
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2
assembly/bios/drivers/sn76489.asm
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@ -40,7 +40,7 @@ Snd_beep:
ld a,%00001000
out (SND_DATA_REG),a
; wait
ld bc, (TIME_DUR_MILLIS * 100)
ld bc, (TIME_DUR_MILLIS * 10)
call Time_delay55
; silence ch1
ld a,%10011111

6
assembly/bios/libs/time.asm
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@ -1,14 +1,16 @@
; Time library
; @author Daniele Verducci
; Duration in cpu cycles / 55 (change these values based on CPU frequency)
TIME_DUR_SECOND: EQU 2545
TIME_DUR_MILLIS: EQU 3
TIME_DUR_SECOND: EQU 1818
TIME_DUR_MILLIS: EQU 2
; Wait bc * 55 states
; Use 1 iteration as delay between I/O bus writes
; @param bc The number of iterations. Each iteration is 55 states long.
Time_delay55:
ret
bit 0,a ; 8
bit 0,a ; 8
bit 0,a ; 8