X-Git-Url: http://git.joshuawise.com/fpgaboy.git/blobdiff_plain/03202f62407e24bd964016dccc06de95df622e3c..39a68cde9f2a76dabfcc9d7654f212ad1d7b356a:/diag.asm

diff --git a/diag.asm b/diag.asm
index 8016400..7f06de0 100644
--- 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