; ; CROMEMCO DAZZLER KALEIDOSCOPE ; WRITTEN BY LI-CHEN WANG ; ; Reformated and commented Oct.2022 H.Franke ;------------------------------------------- ; Memory Structure ; 0100..017F Program ; 0180..01FF Stack (6 bytes used) ; 0300..0AFF Video Buffer TOP@ST EQU 100H VID@BF EQU 200H ; Dazzler Video Registers ; Address Register at I/O Address 0Eh ; Bit 8 = On/Off ; Bit 6..1 = Address of Video Buffer DAZ@A EQU 0EH ; Dazzler Address Port Address DAZ@ON EQU 80H ; On/Off Bit ; Mode Register at I/O Address 0Fh ; Bit 8 = unused ; Bit 7 = Resolution ; 0 = Normal Resolution: 32x32x4 or 64x64x4 ; 1 = High Resolution: 64x64x1 or 128x128x1 ; Bit 6 = Memory Size ; 0 = 512 Bytes ; 1 = 2 KiB ; Bit 5 = Colour or B&W ; 0 = B&W ; 1 = Colour ; Bit 4..1 = IBGR or Grey Level for set pixel in High Resolution (Bit 7 set) ;[Nowadays one would combine bit 7..5 into a video mode number like ; 0 (000) = 32 x 32 x 16 grey level per pixel ; 1 (001) = 32 x 32 x 16 colour per pixel ; 2 (010) = 64 x 64 x 16 grey level per pixel ; 3 (011) = 64 x 64 x 16 colour per pixel ; 4 (100) = 64 x 64 B&W with one predefined grey level and black ; 5 (101) = 64 x 64 colour with one predefined colour and black ; 6 (110) = 128 x 128 B&W with one predefined grey level and black ; 7 (111) = 128 x 128 colour with one predefined colour and black ;] DAZ@M EQU 0FH ; Dazzler Address Port Address DAZ@HR EQU 40h ; High Resolution (1) DAZ@ML EQU 20h ; Memory Size 512 Bytes (0) or 2 KiB (1) DAZ@CO EQU 10h ; Colour (1) or B&W (0) ; Synchronisation Register at I/O Address 0Eh ;[Added for completeness, not used here] ; Bit 8 = Even/Odd video line ; Bit 7 = End of Frame - Set during vertical retrace ; Bit 6..1 = Undefined DAZ@S EQU 0EH ; Dazzler Synchronization Port Address DAZ@SL EQU 40h ; Line Synchronisation DAZ@SF EQU 40h ; Frame Synchronisation ORG 0000H ; Program Start at Reset ; Initialize Stack LXI SP,TOP@ST ; Set Top of Stack to 100h ; Switch Dazzler output on and set address to 0200h MVI A,DAZ@ON+(VID@BF SHR 9) ; Enable Dazzler and set the video buffer start to 0200h (=081h) OUT DAZ@A ; Send to address port ; Set Dazzler Video Mode to 64x64 @ 16 Individual Colours MVI A,DAZ@ML+DAZ@CO ; (=30h) OUT DAZ@M ; Send to mode port ; Main Loop HKS: ; Register usage during main loop: ; H = Colour, cycles from 1Fh down to 01h ; Every odd cycle uses black ; Every even will produce a colour from F down to 1 (Black (0) will not be reached) ; D = Mask (0..FFh) used to 'randomize' the next address ; E = loop counter, counts down from 03FH to 0 ; B = X coordinate * 8 ; C = Y coordinate * 8 ; Note: ; **No register is initialized prior to first iteration** ; They may contain random values after RESET. ; This will result in start at some location with some colour. ; Generate next 'random' pixel coordinate ; New Y = Last Y + ((Last X >> 2) AND MASK) MOV A,B ; Last X >> 2 RRC RRC ANA D ; AND Mask ADD C ; plus Last Y MOV C,A ; -> New Y ; New X = Last X - ((New Y >> 2) AND MASK) RRC ; New Y >> 2 RRC ANA D ; AND Mask MOV L,A MOV A,B ; Last X SUB L MOV B,A ; -> New X ; Start drawing PUSH B ; Save registers to free them for data during drawing PUSH D PUSH H LXI D,0 ; Clear colour(s) (setting to black) in DE MOV A,H ; Extract colour from H and prepare test for draw or clear ANI 01FH RAR ; Low bit defines if black or other colour is used JC DBLACK ; Bit was 0 -> draw pixel as black ; If it was not black, copy the 4-bit value into E and D MOV E,A ; Colour to E for low pixel RLC ; Shift colour to high nibble for upper pixel RLC RLC RLC MOV D,A ; DBLACK: ; Draw a pixel mirrored 4 times ; ; In: ; B/C = X/Y 0..31 in top 5 bits ; D/E = Prepared colour value ; Works out quite easy, as the Dazzler memory in 2Ki mode ; is organized as 4 pages of 512 Bytes, each holding 1/4th ; of the display, 32x32 pixel in the selected mode. They ; are positioned as: ; ; 0200h I 0400h ; Page 1 I Page 2 ... I ... ; I 03FFh I 05FFh ; --------+-------- -------+------- ; I 0600h I 0800h ; Page 3 I Page 4 ... I ... ; 07FFh I 09FFh ; ; Due to this organization in 4 quadrants it's quite easy ; to mirror a pixel's coordinates along both axis by simply ; negating each axis. ; ; Drawing is done clockwise starting in the lower right quadrant ; Draw Pixel in lower right quadrant MVI H,08H ; H = Base Address Page 4, B/C=X/Y pixel within that page CALL OUTPX ; Set pixel at X/Y ; Draw Pixel in lower left quadrant MOV A,B ; Complement B to flip along X axis CMA MOV B,A MVI H,06H ; H = Base Address Page 3, B/C=X/Y pixel within that page CALL OUTPX ; Set pixel at -X/Y ; Draw Pixel in upper left quadrant MOV A,C ; Complement C to flip along Y axis CMA MOV C,A MVI H,02H ; H = Base Address Page 1, B/C=X/Y pixel within that page CALL OUTPX ; Set pixel at -X/-Y ; Draw Pixel in upper right quadrant MOV A,B ; Complement B (again) to flip (back) along X axis CMA MOV B,A MVI H,04H ; H = Base Address Page 2, B/C=X/Y pixel within that page CALL OUTPX ; Set pixel at X/-Y ; Drawing complete, main loop continues POP H ; Restore registers for main loop POP D POP B DCR E ; Have we done this 64 times? JNZ HKS ; No -> back to the top of the loop ; Every 64th cycle, bump the colors, locations and mask to randomize drawing INR B ; X = X + 1/8th INR C ; Y = Y + 1/8th MVI E,03FH ; Prepare another 64 rounds DCR H ; But use the next colour (1Fh..1h) ; Lowest bit flips between black and colour 0..F JNZ HKS ; Unless Black -> Do next iteration INR D ; Increment mask for 'randomness' MVI H,01FH ; Restart with colour 0Fh again JMP HKS ; Start over ; Output a Pixel subroutine ; In: ; H High byte page base (2/4/6/8) ; L --- ; B X coordinate within page (Bit 8..5 -> A3..A0 bit 4 -> selects high/low pixel) ; C Y coordinate within page (Bit 8..4 -> A8..A4) ; D Prepared Colour for Low Pixel (in bit 4..1) ; E Prepared Colour for High Pixel (in bit 8..5) ; Out: ; Pixel Set ; A,H,L destroyed ; B,C,D,E unchanged ; Step one: ; Turn 5+5 bit x/y address into 9 bit address ; plus high/low pixel marker OUTPX: MOV A,C ; Upper 5 bits of pixel address ANI 0F8H ; Extract under Mask RAL ; Move high bit to Carry MOV L,A ; Save to low byte of HL pointer MOV A,H ; Get page base ACI 00H ; Add high bit to high byte of HL pointer MOV H,A ; Save to high byte of HL pointer MOV A,B ; Lower 5 bit of pixel address ANI 0F8H ; Extract under Mask RAR ; Move top 4 to lower nibble, lowest to carry RAR RAR RAR PUSH PSW ; Preserve Carry Flag holding the pixel 'address' ADD L ; Add lower nibble to low byte of HL pointer MOV L,A ; Save to low bye of HL pointer POP PSW ; Restore Carry flag containing the lowest pixel address ; CY=0 Low Pixel; CY=1 High Pixel ; Step two: ; Set high or low Pixel, according to the carry bit, to the drawing colour MOV A,M ; Read existing pixel pair JC OUTHPX ; CY set -> go do high pixel ; CY cleared -> do low pixel ; Output Low Pixel ANI 0F0H ; Mask out (clear) old low pixel ADD E ; Insert new low pixel MOV M,A ; Store in video buffer RET ; Output High Pixel OUTHPX: ANI 0FH ; Mask out (clear) old high pixel ADD D ; Insert new high pixel MOV M,A ; Store in video buffer RET END