RE: [stella] Displaying scores - how?

Subject: RE: [stella] Displaying scores - how?
From: Robert "A." Colbert <colbertb@xxxxxxxxxxxx>
Date: Tue, 11 Mar 1997 08:41:07 -0600

	You may want to check out the source code for Cheetah.  It uses the 6 digit
	code necessary.  Please note that I wrote this code before I knew what I was doing
	so the movit routine is missing since it is ugly.  It is basically just a delay loop and then
	a RESP0 and a RESP1.  Here is an excerpt from the code:

    lda  #$03           ; set both players to 3 copies
    sta  NUSIZ0
    sta  NUSIZ1
    lda  #$01           ; set vertical delay on for both players
    sta  VDELP0
    sta  VDELP1
    ldx  #$6            ; move players 12 columns over
    ldy  #$0
    jsr  movit
    lda  #$f0           ; set player 0 to move left 1 pixel
    sta  HMP0
    sta  WSYNC
    sta  HMOVE          ; move player 0
    lda  SCANLINE       ; adjust scanline count
    sbc  GRHEIGHT
    sta  SCANLINE

    ldy  GRHEIGHT
    lda  ($AA),y        ; get player0 copy1 data
    sta  GRP0          
    sta  WSYNC
    lda  ($AC),y        ; get player1 copy1 data
    sta  GRP1
    lda  ($AE),y        ; get player0 copy2 data
    sta  GRP0
    lda  ($B0),y        ; get player1 copy2 data
    sta  $E9
    lda  ($B2),y        ; get player0 copy3 data
    lda  ($B4),y        ; get player1 copy3 data
    lda  $E9
    sta  GRP1
    stx  GRP0
    sty  GRP1
    sta  GRP0
    dec  GRHEIGHT
    bpl  loop2          ; loop until done
    lda  #$00           ; clear player graphics
    sta  GRP1
    sta  GRP0

>Reply to your message of 3/11/97 7:54 AM
	>Before I spend a week barking up the wrong tree, can someone reveal how
	>2600 games display scores?  (not playfield like Combat, I mean high-res
	>like Missile Command, Millipede, Defender, Pac-man, etc.)  I suspect its
	>three copies of each player, rewriting GRP0 and GRP1 between display of
	>each copy.. am I right?  This would account for the six-digit limit on
	>all 2600 games I've seen except Dark Cavern, which had three dummy zeroes
	>If I'm right, is there any easy way to rip the font used in one of those
	>games so I don't have to reinvent the wheel?  (also, using the same
	>typeface might lend an air of classic-game credibility to the program.)
>End of message

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