[Coco] Dragon Slayer - Black Border Patch!

Steven Wallis stevenw890 at gmail.com
Mon May 11 22:29:19 EDT 2020


                  DRAGON SLAYER - BLACK BORDER PATCH!
                  -----------------------------------
            Start, End and Exec Addresses (original ones):
            400-5FF, E00-7EFF, 182-184, 4000

https://drive.google.com/open?id=1rcntcYtw51tCF5yIYHgqcGLC4tGo1_dH


This was a hard game to patch, it has 3 load addresses and it
automatically executes.

NOTE1: This is not a perfect patch, I put my "video mode & RGB colors"
code on the opening text screen.  It's not really a problem though.

NOTE2: The letters & the sword do not look as good with this patch.
The game still looks alot better patched than the original does with
the white border!  Do the letters look better on a real CoCo 3??


Changes to the original Dragon Slayer:
--------------------------------------
I edited the .dsk file with HxD hex editor.

$1A5-1DE   I added my "video mode & RGB colors" code here (see the
           VM.ASM code below).

$14B10     Changed to $5A0.  I think these 3 bytes get loaded into
           $182-184, which makes the game auto-execute at $400.
           (Was $4000)

$14B15     Changed to $5A0.  This is the Exec Address, I changed it to
           the Exec Address of my code.  (Was $4000)
           (I don't think this gets used, since it gets forced above.)


The colors can be changed at:
-----------------------------
$24  Black
$29  Blue
$2E  Red (now Orange)
$33  White



"VM.ASM"
--------
THIS SETS THE COCO3 VIDEO MODE TO 256X192 4 COLORS.
Changes to my original:
* The colors are closer to the original Dragon Slayer.
* The Vertical Offset.
* Thee jump address at the end jumps to $4000 (the normal Dragon Slayer
  Exec Address).

00010 ORG $5A0
00020 BEGIN JMP START
00030 FDB DONE-BEGIN
00040 * COCO COMPAT MODE
00050 START LDA #$7E
00060 STA $FF90
00070 * MMU-DON'T NEED THIS
00080 LDA #$00
00090 STA $FF91
00100 * BIT PLANE GRP-NOT ALPHA TEXT
00110 LDA #$80
00120 STA $FF98
00130 * VIDEO MODE-256X192 4 COLORS
00140 LDA #$09
00150 STA $FF99
00160 * VERTICAL OFFSET 1
00170 LDA #$E1
00180 STA $FF9D
00190 * VERTICAL OFFSET 2
00200 LDA #$C0
00210 STA $FF9E
00220 * RGB PALETTE - BLACK
00230 LDA #$00
00240 STA $FFB0
00250 * RGB PALETTE - BLUE
00260 LDA #$09
00270 STA $FFB1
00280 * RGB PALETTE - RED (WAS RED=24 NOW ORANGE=26)
00290 LDA #$26
00300 STA $FFB2
00310 * RGB PALETTE - WHITE
00320 LDA #$3F
00330 STA $FFB3
00340 * BORDER COLOR!
00350 LDA #$00
00360 STA $FF9A
00370 * EXEC DRAGON SLAYER...
00380 JMP $4000
00390 DONE EQU *
00400 END START


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