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89 lines
2.1 KiB
89 lines
2.1 KiB
;==================================================================================================
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; MEMORY BANK MANAGEMENT
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;==================================================================================================
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;
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; SELECT THE REQUESTED 32K BANK OF RAM/ROM INTO THE LOWER 32K OF CPU ADDRESS SPACE.
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; LOAD DESIRED BANK INDEX INTO A AND CALL BNKSEL.
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;______________________________________________________________________________________________________________________
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;
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#IF ((PLATFORM == PLT_N8VEM) | (PLATFORM == PLT_ZETA))
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BNKSEL:
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OUT (MPCL_ROM),A
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OUT (MPCL_RAM),A
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RET
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#ENDIF
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;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
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; ZETA SBC V2 USES 16K PAGES. ANY PAGE CAN BE MAPPED TO ONE OF FOUR BANKS:
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; BANK_0: 0K - 16K; BANK_1: 16K - 32K; BANK_2: 32K - 48K; BANK_3: 48K - 64K
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; THIS BNKSEL EMULATES N8VEM / ZETA BEHAVIOR BY SETTING BANK_0 and BANK_1 TO
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; TWO CONSECUTIVE PAGES
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#IF (PLATFORM == PLT_ZETA2)
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BNKSEL:
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BIT 7,A
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JR Z,BNKSEL_ROM ; JUMP IF IT IS A ROM PAGE
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RES 7,A ; RAM PAGE REQUESTED: CLEAR ROM BIT
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ADD A,16 ; ADD 16 x 32K - RAM STARTS FROM 512K
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;
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BNKSEL_ROM:
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RLCA ; TIMES 2 - GET 16K PAGE INSTEAD OF 32K
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OUT (MPGSEL_0),A ; BANK_0: 0K - 16K
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INC A
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OUT (MPGSEL_1),A ; BANK_1: 16K - 32K
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RET
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#ENDIF
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;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
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#IF (PLATFORM == PLT_N8)
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BNKSEL:
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BIT 7,A
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JR Z,BNKSEL_ROM
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;
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BNKSEL_RAM:
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RES 7,A
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RLCA
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RLCA
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RLCA
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OUT0 (CPU_BBR),A
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LD A,DEFACR | 80H
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OUT0 (ACR),A
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RET
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;
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BNKSEL_ROM:
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OUT0 (RMAP),A
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XOR A
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OUT0 (CPU_BBR),A
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LD A,DEFACR
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OUT0 (ACR),A
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RET
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;
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#ENDIF
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;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
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#IF (PLATFORM == PLT_MK4)
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BNKSEL:
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RLCA
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RLCA
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RLCA
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OUT0 (CPU_BBR),A
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RET
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#ENDIF
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;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
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;
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; NOTE: S2I HAS NO BANKED MEMORY!
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; ALL FUNCTIONALITY IS NULLED OUT HERE.
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;
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#IF (PLATFORM == PLT_S2I)
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BNKSEL:
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RET
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#ENDIF
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;;;;;;;;;;;;;;;;;;;;
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; EOF - MEMMGR.ASM ;
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;;;;;;;;;;;;;;;;;;;;
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