mirror of
https://github.com/deater/dos33fsprogs.git
synced 2024-11-01 01:06:33 +00:00
239 lines
5.3 KiB
ArmAsm
239 lines
5.3 KiB
ArmAsm
; This took a while to track down
|
|
; On Apple II/II+ the horiz blanking addr are $1000 higher than on IIe
|
|
; So on II+ were outside video area, so unlikely to be our set value
|
|
; (unless I foolishly use $ff which some uninitialized mem is set to)
|
|
; Lots of this color fiddling is to make sure you don't accidentally
|
|
; get runs of colors on IIe due to the horiz blank
|
|
|
|
; 0-5 aqua 6-12 = grey, 13 - 20 = yellow, 21-23 = aqua rainbow 14
|
|
;
|
|
;
|
|
;16 0 YA
|
|
;17 1 YA
|
|
;18 2 YA
|
|
;19 3 YA
|
|
;20 4 YA
|
|
;21 5 AA
|
|
;22 6 AG
|
|
;23 7 AG
|
|
;0 8 AG
|
|
;1 9 AG
|
|
;2 10 AG
|
|
;3 11 AG
|
|
;4 12 AG
|
|
;5 13 AY ****
|
|
;6 14 GY RAINBOW
|
|
;7 15 GY
|
|
;8 16 GY
|
|
;9 17 GY
|
|
;10 18 GY
|
|
;11 19 GY
|
|
;12 20 GY
|
|
;13 21 YA
|
|
;14 22 YA
|
|
;15 23 YA
|
|
|
|
|
|
|
|
;==============================
|
|
; setup graphics for vapor lock
|
|
;==============================
|
|
vapor_lock:
|
|
|
|
; Clear Page0
|
|
lda #$0
|
|
sta DRAW_PAGE
|
|
lda #$ee ; full screen white $ff
|
|
jsr clear_gr
|
|
|
|
lda #$dd
|
|
ldy #40
|
|
jsr clear_page_loop ; make bottom half yellow $dd
|
|
|
|
lda #$aa
|
|
ldy #24
|
|
jsr clear_page_loop ; make middle grey2 $aa
|
|
|
|
lda #$ee
|
|
ldy #10
|
|
jsr clear_page_loop ; make top half aqua $ee
|
|
|
|
; set up a rainbow to aid in exact lock
|
|
|
|
ldy #00
|
|
rainbow_loop:
|
|
tya
|
|
sta $728+20,Y
|
|
iny
|
|
cpy #20
|
|
bne rainbow_loop
|
|
|
|
;btt:
|
|
; jmp btt
|
|
|
|
|
|
;=====================================================
|
|
; attempt vapor lock
|
|
; by reading the "floating bus" we can see most recently
|
|
; written value of the display
|
|
;=====================================================
|
|
; See:
|
|
; Have an Apple Split by Bob Bishop
|
|
; Softalk, October 1982
|
|
|
|
; Challenges: each scan line scans 40 bytes.
|
|
; The blanking happens at the *beginning*
|
|
; So 65 bytes are scanned, starting at adress of the line - 25
|
|
|
|
; the scan takes 8 cycles, look for 4 repeats of the value
|
|
; to avoid false positive found if the horiz blanking is mirroring
|
|
; the line (max 3 repeats in that case)
|
|
|
|
vapor_lock_loop:
|
|
|
|
; first make sure we have a full line of $aa
|
|
|
|
lda #$aa ; 2
|
|
zxloop:
|
|
ldx #$04 ; 2
|
|
wiloop:
|
|
cmp $C051 ; read the floating bus ; 4
|
|
bne zxloop ; if not, start from scratch ; 2/3
|
|
dex ; we were, dec ; 2
|
|
bne wiloop ; if not 4 of them, restart ; 3/2
|
|
|
|
; if we get here we read 4 proper pixels, 11 apart (2+4+2+2+3)
|
|
; 0 11 22 33, clock at 34
|
|
; 1 12 23 34, clock at 35
|
|
; 2 13 24 35, clock at 36
|
|
; 3 14 25 36, clock at 37
|
|
; 4 15 26 37, clock at 38
|
|
; 5 16 27 38, clock at 39
|
|
; 6 17 28 39, clock at 40
|
|
|
|
|
|
; X X X X
|
|
; X X X X
|
|
; X X X X
|
|
; X X X X
|
|
; X X X X
|
|
; X X X X
|
|
; X X X X
|
|
; 0123456789012345678901234 0123456789012345678901234567890123456789
|
|
; 1 2 1 2 3
|
|
; hsync pixels
|
|
; XXXXXXXXXXXXXXXXXXXXXXXXX 4444444444444444444444444444440123456789
|
|
|
|
; now look for the color change that
|
|
; happens at line 13*8 = 104
|
|
|
|
lda #$dd ; 2
|
|
zloop:
|
|
ldx #$04 ; 2
|
|
qloop:
|
|
cmp $C051 ; read floating bus ; 4
|
|
bne zloop ; 2/3
|
|
dex ; 2
|
|
bne qloop ; 3/2
|
|
;============
|
|
; 11
|
|
|
|
; Found it!
|
|
; if we get here we read 4 proper pixels, 11 apart (2+4+2+2+3)
|
|
; 0 11 22 33, clock at 34
|
|
; 1 12 23 34, clock at 35
|
|
; 2 13 24 35, clock at 36
|
|
; 3 14 25 36, clock at 37
|
|
; 4 15 26 37, clock at 38
|
|
; 5 16 27 38, clock at 39
|
|
; 6 17 28 39, clock at 40
|
|
|
|
|
|
|
|
|
|
;btt:
|
|
; jmp btt
|
|
|
|
; In theory near end of line 104
|
|
|
|
; now skip ahead 8 lines and read from the rainbow pattern we set
|
|
; up to find our exact location
|
|
|
|
; delay 65 * 8 = 520
|
|
; we back off a few to make sure we're not in the horiz blank
|
|
; try to delay 510
|
|
|
|
; *NOTE* sometimes we end up going one (or rarely, two??) lines too far
|
|
; so instead try going 7 lines ahead, and if still dd then one more
|
|
|
|
; so single step until we get a rainbow color
|
|
|
|
; go to next line, -10
|
|
lda #28 ; 2
|
|
jsr delay_a ; delay 25+28 = 53
|
|
; total delay = 55
|
|
|
|
vl_try_again:
|
|
lda #29 ; 2
|
|
jsr delay_a ; delay 25+29 = 54
|
|
; total delay = 56
|
|
|
|
|
|
|
|
lda $C051 ; 4
|
|
cmp #$dd ; 2
|
|
beq vl_try_again ; 3
|
|
; -1
|
|
|
|
|
|
; now near end of line 112
|
|
;lda $0 ; nop to match old code ; 3
|
|
; nop ; nop to match old code ; 2
|
|
|
|
lda $C051 ; 4
|
|
;kbb:
|
|
; jmp kbb
|
|
|
|
; we are in theory on line $728 = 14*8 = 112
|
|
; so 112*65 = 7280 cycles from start
|
|
|
|
; we are actualy 25+20+A pixels in
|
|
; 7325+A
|
|
|
|
; Our goal is line 114 at 7410 cycles
|
|
; 7410 - 7325 = 85
|
|
|
|
; so kill 85-A cycles
|
|
; -6 to do subtraction
|
|
; -6 for rts
|
|
; -25 for delay_a overhead
|
|
|
|
eor #$ff ; 2
|
|
sec ; 2
|
|
adc #48 ; 2
|
|
|
|
jsr delay_a ; should total 48 cycles
|
|
|
|
|
|
done_vapor_lock:
|
|
rts ; 6
|
|
|
|
|
|
|
|
|
|
; Some random related work
|
|
; Docs:
|
|
; Lancaster
|
|
; Bishop
|
|
; Sather
|
|
|
|
; Vaguely relevant but no help with the Apple II+ issue
|
|
;
|
|
; Eamon: Screen display and timing synchronization
|
|
; on the Apple IIe and Apple IIgs
|
|
;
|
|
; Adams: Visually presented verbal stimuli by assembly
|
|
; language on the Apple II computer.
|
|
; Cavanagh and Anstis: Visual psychophysics on the
|
|
; Apple II: Getting started
|