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; This ROM is a simple example of how to use serial connections.
; It will wait to receive text via the serial connection, save the text in memory until it encounters a new line (without overflow check), then send back in ASCII "Astatin" and a new line followed by the text that was received.
.PADTO 0x0058
JP =Serial_Recv
.PADTO 0x0100
Entry:
JP =Start
.PADTO 0x0104
Nintendo_Logo: ; The Nintendo logo must be stored in bytes 0x104-133
.DB $CE,$ED,$66,$66,$CC,$0D,$00,$0B,$03,$73,$00,$83,$00,$0C,$00,$0D
.DB $00,$08,$11,$1F,$88,$89,$00,$0E,$DC,$CC,$6E,$E6,$DD,$DD,$D9,$99
.DB $BB,$BB,$67,$63,$6E,$0E,$EC,$CC,$DD,$DC,$99,$9F,$BB,$B9,$33,$3E
.PADTO 0x0134
Checksum: ; The bytes 0x134-0x14d need to add up to 0xe7 (= 0xff - 0x19)
.DB $00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00
.DB $00,$00,$00,$00,$00,$00,$00,$00,$00,$e7
Start:
LD SP, $fffe
LD A, $00
LD ($40), A
LD A, $08
LD ($ff), A
LD HL, $c000
EI
Lock:
HALT
EI
JR =Lock
Serial_Recv:
LD A, ($01)
CP $0a
CALL Z, =Read_back
LD (HL+), A
RETI
Read_back:
LD (HL), $00
LD HL, =Astatin_ASCII
CALL =Print
LD HL, $c000
CALL =Print
JP =Start
Astatin_ASCII:
.DB $41, $73, $74, $61, $74, $69, $6e, $0a $00
Print:
.send_loop:
LD A, (HL+)
CP $00
RET Z
LD ($01), A
LD A, $81
LD ($02), A
.wait_transfer:
LD A, ($02)
BIT 7, A
JR NZ, =.wait_transfer
JR =.send_loop
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