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PGM_BYTE
; programs byte to the given location
; address in EHL (512kB only)
; byte in A
; preserves BC,DE,HL
; returns carry=1 if error
PUSH DE
PUSH HL
PUSH AF
LD E,0X00
LD HL,0X0555
LD A,0XAA
CALL WRBYTE
LD HL,0X2AA
LD A,0X55
CALL WRBYTE
LD HL,0X555
LD A,0XA0
CALL WRBYTE
POP AF
POP HL
POP DE
CALL WRBYTE
JP ERR_END ; wait for end/error as always
sendCmd:
ld bc,0xfff7
ld a,0x3f & (~(1))
out (c),a
ld a,0xaa
ld (0x1555 + 0xc000),a
ld a,0x3f & (~(0))
out (c),a
ld a,0x55
ld (0x2aaa + 0xc000),a
ld a,0x3f & (~(1))
out (c),a
ld a,e
ld (0x1555 + 0xc000),a
ret
rom_read_id ; out: hl - ChipID
ld e,0xf0
call sendCmd
ld e,0x90
call sendCmd
LD A,87
DEC A
JR NZ,$-1
ld hl,(0xc000)
ld e,0xf0
call sendCmd
ret
erase_all_chip
ld e,0xf0
call sendCmd
ld e,0x80
call sendCmd
ld e,0x10
call sendCmd
;now wait 100uS @ 14MHz to start actual block erase
LD A,87
DEC A
JR NZ,$-1
ld hl, 0xc000
ERASE_ALL_LOOP
ld a,(hl)
xor (hl)
jr nz,ERASE_ALL_LOOP
ld e,0xf0
call sendCmd
ret
ERASE_BLK
; erases 64kB block of ROM.
; block address is given in EHL (any addr in block)
; returns carry=1 if error
; BC,DE,HL are preserved
PUSH DE
PUSH HL
LD E,0X00
LD HL,0X0555
LD A,0XAA
CALL WRBYTE
LD HL,0X2AA
LD A,0X55
CALL WRBYTE
LD HL,0X555
LD A,0X80
CALL WRBYTE
LD A,0XAA
CALL WRBYTE
LD HL,0X2AA
LD A,0X55
CALL WRBYTE
POP HL
POP DE
LD A,0X30
CALL WRBYTE
;now wait 100uS @ 14MHz to start actual block erase
LD A,87
DEC A
JR NZ,$-1
; then wait for erase end
ERR_END
CALL WAIT_END
RET NC ; if no error - return
; send read/reset command to ROM
LD A,0XF0
CALL WRBYTE
;then wait 10uS @ 14MHz
LD A,9
DEC A
JR NZ,$-1
SCF
RET ; set error condition
WAIT_END;wait for ROM to end op or to indicate error
PUSH BC
WE_REPEAT
CALL RDBYTE
LD B,A
CALL RDBYTE
XOR B
BIT 6,A
JR Z,WE_END ; no toggle - end! (carry is clear)
BIT 5,A
JR NZ,WE_REPEAT ; if toggle and error bit toggles -
; repeat reading
BIT 5,B ; toggle, error bit is set - error!
JR Z,WE_REPEAT ; otherwise - just toggle, wait more
;WE_ERROR
SCF
WE_END POP BC
RET
WRBYTE ; writes given in A byte to rom at address EHL
; in a range 0..512kB
; assumes shadow ports are on
; uses paging in 0XC000..0XFFFF window
; preserves A,BC,DE,HL
PUSH BC
PUSH AF
LD A,E
AND 7 ; 512kB only
LD B,A
LD A,H
AND 0XC0
OR B
RLCA
RLCA
CPL
AND 0X3F
;;;;;;;;OR 0X00
LD BC,WIN_A3;0XFFF7
OUT (C),A ; page is done
LD A,H
OR 0XC0
LD B,A
LD A,L
LD C,A
POP AF
LD (BC),A
POP BC
RET
RDBYTE ; read byte (same as WRBYTE), reads in A
PUSH BC
LD A,E
AND 7 ; 512kB only
LD B,A
LD A,H
AND 0XC0
OR B
RLCA
RLCA
CPL
AND 0X3F
;;;;;;;;OR 0X00
LD BC,WIN_A3;0XFFF7
OUT (C),A ; page is done
LD A,H
OR 0XC0
LD B,A
LD A,L
LD C,A
LD A,(BC)
POP BC
RET