Exidy Experiment

[ClausB]

512 x 240 bitmap graphics:

https://forum.vcfed.org/index.php?threa ... t.1252681/

20250418_092646.jpg (247.66 KiB) Viewed 7206 times

[RedskullDC]

Thanks for the heads up, that's very kool !

Cheers,
Leslie

[ClausB]

Block diagram:

ExBmSche.png (1.72 KiB) Viewed 3579 times

[ClausB]

Z80 code as posted on the VCF thread.

Code: Select all

0078                   ORG     78H
 0078 0000      XCO:    DFB     0,0         ; x coord
 007A 00        YCO:    DFB     0           ; y coord
              
 007B 2A7800            LD      HL,(XCO)    ; Plot pt at x,y
 007E 7D        PLOT:   LD      A,L
 007F E607              AND     #7
 0081 4F                LD      C,A         ; bit index
 0082 7D                LD      A,L
 0083 E6F8              AND     #0F8H
 0085 6F                LD      L,A
 0086 29                ADD     HL,HL
 0087 3A7A00            LD      A,(YCO)
 008A E60F              AND     #0FH
 008C 5F                LD      E,A
 008D 16FC              LD      D,#0FCH
 008F 19                ADD     HL,DE       ; byte ptr
 0090 3A7A00            LD      A,(YCO)
 0093 0F                RRC     A
 0094 0F                RRC     A
 0095 0F                RRC     A
 0096 0F                RRC     A
 0097 3C                INC     A           ; bank 1-15
 0098 E60F              AND     #0FH
 009A 47                LD      B,A
 009B D3FE              OUT     (0FEH),A    ; select bank
 009D 11BF00            LD      DE,#BITS
 00A0 7B                LD      A,E
 00A1 81                ADD     A,C         ; index into bit table
 00A2 5F                LD      E,A
 00A3 1A                LD      A,(DE)      ; pixel on: bit pattern
 00A4 B6                OR      (HL)
 00A5 77                LD      (HL),A      ; OR to screen
 00A6 1A                LD      A,(DE)      ; pixel off:
 00A7 2F                CPL                 ; invert bit pattern
 00A8 4F                LD      C,A
 00A9 2C        DOWN:   INC     L           ; next y down
 00AA 7D                LD      A,L
 00AB E60F              AND     #0FH
 00AD 200B              JR      NZ,POFF
 00AF 7D                LD      A,L
 00B0 D610              SUB     #10H
 00B2 6F                LD      L,A
 00B3 04                INC     B           ; next bank
 00B4 78                LD      A,B
 00B5 E60F              AND     #0FH
 00B7 C8                RETZ
 00B8 D3FE              OUT     (0FEH),A    ; select bank
 00BA 79        POFF:   LD      A,C         ; pixel off
 00BB A6                AND     (HL)
 00BC 77                LD      (HL),A      ; AND to screen
 00BD 18EA              JR      DOWN
 00BF 80402010  BITS:   DFB     80H,40H,20H,10H
 00C3 08040201          DFB     8,4,2,1
              
 00C7 1180F0            LD      DE,#0F080H  ; Fill screen with user chars
 00CA 21C0F0            LD      HL,#0F0C0H
 00CD 018000            LD      BC,#80H
 00D0 79        FILL:   LD      A,C         ; 80-FF
 00D1 12        LOOP:   LD      (DE),A      ; 30 lines of 64 chars   
 00D2 13                INC     DE
 00D3 3C                INC     A
 00D4 77                LD      (HL),A   
 00D5 23                INC     HL
 00D6 3C                INC     A
 00D7 20F8              JR      NZ,LOOP
 00D9 EB                EX      DE,HL
 00DA 09                ADD     HL,BC
 00DB 7C                LD      A,H
 00DC FEF8              CP      #0F8H       ; F080-F7FF
 00DE 20F0              JR      NZ,FILL     ; (512 h x 240 v pixels)
              
 00E0 210000            LD      HL,#0       ; Clear screen
 00E3 44                LD      B,H
 00E4 3E01              LD      A,#1        ; start bank 1
 00E6 ED73F700          LD      (STK+1),SP  ; save SP into instruction at STK below
 00EA D3FE      MOVE:   OUT     (0FEH),A    ; select bank
 00EC F9                LD      SP,HL       ; borrow stack ptr
 00ED E5        CLR:    PUSH    HL          ; user char RAM FC00-FFFF
 00EE E5                PUSH    HL
 00EF 10FC              DJNZ    CLR         ; 256*4
 00F1 3C                INC     A           ; next bank
 00F2 FE10              CP      #16         ; thru bank 15
 00F4 20F4              JR      NZ,MOVE
 00F6 313412    STK:    LD      SP,#1234H   ; restore stack ptr (modified above)
 00F9 C9                RET 
 

[ClausB]

And the BASIC code with output:

20250422_211623.jpg (211.38 KiB) Viewed 954 times