Video RAM cut 1 -- on distributed ram

[fpgaboy.git] / diag.asm

diff --git a/diag.asm b/diag.asm
index 80164004fea23ecde8dc9fcdd67c005c506978de..7f06de0ce42223f19f4dc2b67a74a5497592e8c8 100644 (file)
--- a/diag.asm
+++ b/diag.asm
@@ -32,6 +32,8 @@ main:
        
        ld hl, signon
        call puts
+
+       call putscreen
        
        ei
 
@@ -48,6 +50,25 @@ main:
 signon:
        db $0D,$0A,$1B,"[1mFPGABoy Diagnostic ROM",$1B,"[0m",$0D,$0A,0
 
+putscreen:
+       ld a, $FF               ; Copy two tiles.
+       ld hl, $8000
+       ld [hli], a
+       ld [hli], a
+       xor a
+       ld [hli], a
+       ld [hli], a
+       
+       ld hl, $9800
+.loop: ld a, $FF
+       ld [hli], a
+       xor a
+       ld [hli], a
+       ld a, h
+       cp $9C
+       jp nz,.loop
+       ret
+
 vbl:
        PUSH AF
        PUSH BC
@@ -55,9 +76,8 @@ vbl:
        PUSH HL
        
        xor a
-       ld c, $0F
-       ld [c], a
-       
+       ld [$FF0F], a
+
        ld c, $42       ; SCY
        ld a, [c]
        inc a
@@ -75,8 +95,7 @@ lcdc:
        PUSH BC
        
        xor a
-       ld c, $0F
-       ld [c], a
+       ld [$FF0F], a
        
        POP BC
        POP AF
@@ -90,25 +109,23 @@ tmro:
        PUSH HL
        
        xor a
-       ld c, $0F
-       ld [c], a
+       ld [$FF0F], a
        
        ld c, $45       ; LYC
        ld a, [c]
        inc a
        ld [c], a
        
-       ld hl, $DF82
-       ld a, [hld]
+       ld a, [$DF82]
        cp 0
        jr z, .noprint
        ld a, $41       ; print A
        call putc
 .noprint:
-       inc [hl]
-       ld a, [hl]
-       ld c, $51
-       ld [c], a
+       ld a, [$DF81]
+       inc a
+       ld [$DF81], a
+       ld [$FF51], a
 
        POP HL
        POP DE
@@ -121,7 +138,7 @@ memtest:
        ld hl,memteststr
        call puts
        
-       ld hl, $C001            ; Write loop
+       ld hl, $C000            ; Write loop
 .wr:
        ld a,h
        xor l
@@ -133,7 +150,7 @@ memtest:
        cp $80
        jr nz, .wr
 
-       ld hl, $C001            ; Read loop
+       ld hl, $C000            ; Read loop
 .rd:
        ld a,h
        xor l
@@ -154,7 +171,7 @@ memtest:
        ret
 .memfail:                      ; Say we failed (sadface)
        ; decrement hl the easy way
-       ld a,[hld]
+       dec [hl]
        push hl
        ld hl, failatstr
        call puts