Apple II

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Apple II

The Apple II is an 8-bit home computer and one of the world's first highly successful mass-produced microcomputer products. It was designed primarily by Steve Wozniak.

Setting up

Compilation can be done as follows (master.dsk can be found with applewin) 

acme hl.asm
java -jar AppleCommander-1.3.5.jar -d master.dsk hl
java -jar AppleCommander-1.3.5.jar -p master.dsk hl B 24576 < hl.bin

Memory Map

   0-255	 $0-$FF     ZERO-PAGE SYSTEM STORAGE
  256-511      $100-$1FF    SYSTEM STACK
  512-767      $200-$2FF    KEYBOARD CHARACTER BUFFER
  768-975      $300-$3CF    OFTEN AVAILABLE AS FREE SPACE FOR USER PROGRAMS
  976-1023     $3D0-3FF     SYSTEM VECTORS
 1024-2047     $400-$7FF    TEXT AND LO-RES GRAPHICS PAGE 1 <--- !!!
 2048-LOMEM    $800-LOMEM   PROGRAM STORAGE
 2048-3071     $800-$BFF    TEXT AND LO-RES GRAPHICS PAGE 2 OR FREE SPACE
 3072-8191     $C00-$1FFF   FREE SPACE UNLESS RAM APPLESOFT IS IN USE
 8192-16383   $2000-$3FFF   HI-RES PAGE 1 OR FREE SPACE <--- !!!
16384-24575   $4000-$5FFF   HI-RES PAGE 2 OR FREE SPACE
24576-38999   $6000-$95FF   FREE SPACE AND STRING STORAGE
38400-49151   $9600-$BFFF   DOS
49152-53247   $C000-$CFFF   I/O HARDWARE (RESERVED)
53248-57343   $D000-$DFFF   APPLESOFT IN LANGUAGE CARD OR ROM
57344-63487   $E000-$F7FF   APPLESOFT OR INTEGER BASIC IN LANGUAGE CARD OR ROM
63488-65535   $F800-$FFFF   SYSTEM MONITOR

Display

Graphics Modes

Text Mode 40x24, for Apple IIe available 80x25 - use PR#3 for switch mode, or hardware switch
LowRes 40x48, 16 colors: https://en.wikipedia.org/wiki/Apple_II_graphics
Hires mode 280x192,6 colors: https://www.xtof.info/blog/?p=768

https://mrob.com/pub/xapple2/colors.html https://archive.org/details/HiRes_Color_Graphics_on_the_Apple_II_Computer_by_Wozniak

However for sizecoding, you almost never want to do direct-access to graphics for Apple II in size-coding because the Apple II graphics modes are horrible. The only fast way to do things is with large lookup tables. To do hires you need to divide by 7 which as you can imagine is a bit difficult to do compactly on 6502. Double-hires is even crazier on top of that. Deater did manage a color-bar style effect in double-hires in 128B but that was doing some crazy tricks with the firmware BASIC routines, definitely not direct-access.

Lores and Hires can be mixed modes and full-graphics The screen structure is called memory holes(https://retrocomputing.stackexchange.com/questions/2534/what-are-the-screen-holes-in-apple-ii-graphics). The GBASCALC($F847) procedure is used to calculate the address of the horizontal line : IN:reg.A=Y, out : GBASL/GBASH($26/$27)=address. See also https://www.callapple.org/uncategorized/use-of-apple-ii-color-graphics-in-assembly-language/

Getting something on screen

Here is an example of a XOR texture, created by g0blinish 

 *=$6000
 !to "HL.bin", plain	; set output file and format
 !cpu 6502		; set processor type

GBASL	=	$26
GBASH	=	$27
SETGR    =     $FB40 ; setup LoRes
GBASCALC = $F847 ; calc Address

CLRTEXT =  $C050 ;display graphics 
SETTEXT =  $C051 ;display text 

CLRMIXED = $C052 ;clear mixed mode- enable full graphics 
SETMIXED = $C053 ;enable graphics/text mixed mode 

PAGE1 =    $C054 ;select text/graphics page1 
PAGE2 =    $C055 ;select text/graphics page2 

CLRHIRES = $C056 ;select Lo-res 
SETHIRES = $C057 ;select Hi-res 

TMP= $FA

	JSR   SETGR      ;GR
	BIT CLRMIXED ; full screen

	LDA #0 ; A=0
	STA TMP ; POKE $FA,A

YLP ;
	LDA TMP ; A=PEEK($FA)
;	LSR ; A=A/2
	JSR GBASCALC
	LDY #0;Y=0

XLP TYA ; A=Y
	EOR TMP ; A=A xor PEEK($FA)
	and #$0F ; A=A and 15
	TAX ; X=A
	LDA COLORS,X ;A=PEEK(COLORS+X)
	STA(GBASL),Y ; POKE PEEK($26)+256*PEEK($27)+Y,A
	INY ; Y=Y+1
	CPY #40 ; Y=40?
	BNE XLP
	INC TMP ; POKE $FA,PEEK($FA)+1
	LDA TMP ; A=PEEK($FA)
	CMP #24 ; A=24?
	BNE YLP
	
M1 JMP M1 ; replace to RTS

COLORS ;N*17, pixel format is AAAABBBB, AAAA - upper dot, BBBB - lower dot
!byte $00,$11,$22,$33,$44,$55,$66,$77
!byte $88,$99,$AA,$BB,$CC,$DD,$EE,$FF

Sound

Here is an example for using the speaker, based onthe following basic program: 

; 50  POKE 768,V: POKE 769,P - 255 *  INT (P / 256): POKE 800,1 + P / 256
; 60  CALL 770: RETURN 
; 95  FOR K = 1 TO N: READ V(K),P(K): NEXT K
; 100  FOR K = 1 TO N:V = V(K):P = P(K)
; 110  GOSUB 50
;!byte 173,48,192,136,208,5,206,1,3,240,9,202,208,245,174,0,3,76,2,3,206,32,3,208,240,96

 *=$6000
 !to "HL.bin", plain	; set output file and format
 !cpu 6502		; set processor type

;start
; 95  FOR K = 1 TO N: READ V(K),P(K): NEXT K
; 100  FOR K = 1 TO N:V = V(K):P = P(K)
ini:
	lda #70
	sta cnt+1
	lda #music&255
	sta gotbyte+1
	lda #music/256
	sta gotbyte+2

lop:
;V
	jsr gotbyte
	sta L300
	jsr gotbyte
;P
	jsr gotbyte
	sta L301
	jsr gotbyte
	clc
	adc #1
	sta L320
	jsr beep
	
	dec cnt+1
cnt lda #70
	bne lop
; 110  GOSUB 50
; 50  POKE 768,V: POKE 769,P - 255 *  INT (P / 256): POKE 800,1 + P / 256
; 60  CALL 770: RETURN 
	jmp ini
gotbyte
	lda music
	inc gotbyte+1
	bne noinch
	inc gotbyte+2
noinch
	rts
;!byte 173,48,192,136,208,5,206,1,3,240,9,202,208,245,174,0,3,76,2,3,206,32,3,208,240,96
beep:
	ldy #1
	ldx #1
loc_302:
		LDA	$C030

loc_305:
		DEY
		BNE	loc_30D
		DEC	L301
loc_30B:
		BEQ	loc_316

loc_30D:
		DEX
		BNE	loc_305
		LDX	L300
		JMP	loc_302
loc_316:
		DEC	L320
		BNE	loc_30B
		RTS
L301 !byte 0
L300 !byte 0
L320 !byte 0
music
 !word 76,192,85,64,96,64,102,64,114,128,114,64,96,64,102,64,114,64,128,64
 !word 114,64,152,64,171,64,152,512,76,192,85,64,96,64,102,64,114,128,114,64
 !word 96,64,102,64,114,64,128,64,114,64,152,64,171,64,152,512,85,64,85,64
 !word 85,64,96,64,144,128,144,64,128,64,76,128,85,64,96,64,144,128,114,64
 !word 96,64,102,128,114,64,128,64,128,128,114,64,128,64,114,512,85,64,85,64
 !word 85,64,96,64,144,128,144,64,128,64,76,128,85,64,96,64,144,128,114,64
 !word 96,64,102,128,114,64,128,64,128,64,128,128,96,64,85,64,96,64,102,64,114,64,114,64

Additional Resources

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