Applesoft BASIC High Resolution Graphics

High Resolution (HiRes) modes

HGR and HGR2 both set hi-resolution graphics mode.
HGR sets a mixed mode of text and graphics (280x160 pixels).
HGR2 sets full-screen graphics mode (280x192 pixels).
When the screen is in HGR mixed mode there are four TEXT-mode lines on the bottom of the screen.

HGR  = hires with text, 1st page starting at memory location `$2000`
HGR2 = hires no text, 2nd page starting at memory location `$4000`
POKE 49234,0 = switch to full-page without text
Poke -16299,0 Switch from high-res page 1 to page 2
Poke -16300,0 Switch from high-res page 2 to page 1
Poke -16302,0 Full screen graphics - no text

Memory Locations

There are two pages of HiRes graphics.
The first page, HGR, starts at $2000
The second page, HGR2, starts at $4000

$E000-FFFF - Monitor ROM / Extended RAM 8 / 8 kB 
$D000-DFFF - BASIC ROM / RAM bank 1 and 2 4 / 4 / 4 kB 
$C800-CFFF - Shared slot ROM memory 2 kB 
$C100-C7FF - Permanent Slot ROM memory 256 per slot 
$C000-C0FF - Softswitches 256 bytes
$6000-BFFF - Free memory 24 kB 
$4000-5FFF - Free memory / Hi-Res page 2 8 kB 
$2000-3FFF - Free memory / Hi-Res page 1 8 kB
$0C00-1FFF - Free memory 5 kB 
$0800-0BFF - Free memory / Text page 2 1 kB 
$0400-07FF - Text page 1 1 kB 
$03D0-03FF - Interrupt vectors 48 bytes 
$0300-03CF - Free memory 208 bytes 
$0200-02FF - Input prompt character buffer 256 bytes 
$0100-01FF - CPU stack 256 bytes 
$0000-00FF - Zero page

High Resolution (HiRes) graphics mode colors

Hi-res modes have just eight colors.

0: black 1
1: green
2: magenta
3: white 1
4: black 2
5: red
6: blue
7: white 2

High Resolution (HiRes) graphics mode BASIC commands

HGR Set display to mixed/high resolution ("hires") graphics mode
HCOLOR= aexpr
HPLOT [TO] aexpr, aexpr [ TO aexpr, aexpr ]

HCOLOR=2 : HPLOT 0,0 : CALL 62454 : REM fill screen with last hcolor

HGR Mixed-Mode Screen Dimensions

     ______________________________
    |(0,0)                  (279,0)|
    |                              |
    |                              | GRAPHICS
    |                              |
    |(0,159)              (279,159)|
    |------------------------------|
    |HTAB  1                       | TEXT
    |VTAB 21                       | 4 rows
    |______________________________|

HGR/HGR2 Full-Screen Screen Dimensions

     ______________________________
    |(0,0)                  (279,0)|
    |                              |
    |                              | GRAPHICS
    |                              |
    |                              |
    |                              |
    |                              |
    |(0,192)              (279,192)|
    |______________________________|

0 HGR : HOME

10 HCOLOR=5
20 HPLOT 0,0 TO 279,0
30 HPLOT TO 279,159
40 HPLOT TO 0,159
50 HPLOT TO 0,0

60 HCOLOR=2
70 HPLOT 0,0   TO 279,159
80 HCOLOR=1
90 HPLOT 0,159 TO 279,0

100 HOME : HTAB 1 : VTAB 21
120 PRINT "Press any key to continue"
130 GET ANS$

140 HOME : HTAB 1 : VTAB 21
160 PRINT "Thank you for playing"

210 HCOLOR=6
220 HPLOT 0,0 TO 279,0
230 HPLOT TO 279,159
240 HPLOT TO 0,159
250 HPLOT TO 0,0
260 HPLOT 0,0   TO 279,159
270 HPLOT 0,159 TO 279,0

Print random balls on the screen

In a not so random way.

0 HGR : POKE 49234,0 : HOME
05 DEF FN RANDOM(X) = (INT(RND(1) * X) + 1)

10 FOR I=1 TO 20

30 LET C = FN RANDOM(7) : HCOLOR=C : LET HPAD= FN RANDOM(250)  : LET VPAD= FN RANDOM(170)  : GOSUB 500
40 LET C = FN RANDOM(7) : HCOLOR=C : LET HPAD= FN RANDOM(250)  : LET VPAD= FN RANDOM(170)  : GOSUB 500
50 LET C = FN RANDOM(7) : HCOLOR=C : LET HPAD= FN RANDOM(250)  : LET VPAD= FN RANDOM(170)  : GOSUB 500
60 LET C = FN RANDOM(7) : HCOLOR=C : LET HPAD= FN RANDOM(250)  : LET VPAD= FN RANDOM(170)  : GOSUB 500
70 LET C = FN RANDOM(7) : HCOLOR=C : LET HPAD= FN RANDOM(250)  : LET VPAD= FN RANDOM(170)  : GOSUB 500

80 NEXT
99 END

500 REM HPAD subroutine
510 IF (C = 0) THEN HCOLOR=1 : REM no black circles
515 IF (C = 4) THEN HCOLOR=5 : REM no black circles
520 HPLOT HPAD + 14,VPAD +  8 TO HPAD + 17,VPAD +  8
525 HPLOT HPAD + 13,VPAD +  9 TO HPAD + 18,VPAD +  9
530 HPLOT HPAD + 12,VPAD + 10 TO HPAD + 19,VPAD + 10
540 HPLOT HPAD + 11,VPAD + 11 TO HPAD + 20,VPAD + 11

550 HPLOT HPAD + 11,VPAD + 12 TO HPAD + 20,VPAD + 12

560 HPLOT HPAD + 11,VPAD + 13 TO HPAD + 20,VPAD + 13
570 HPLOT HPAD + 12,VPAD + 14 TO HPAD + 19,VPAD + 14
580 HPLOT HPAD + 13,VPAD + 15 TO HPAD + 18,VPAD + 15
590 HPLOT HPAD + 14,VPAD + 16 TO HPAD + 17,VPAD + 16
999 RETURN