Instruction manual

0005 d3 03 out (3),a ;write to control port

0007 3e 37 ld a,037h ;enable receive and transmit

0009 d3 03 out (3),a ;write to control port

000b c9 ret

000c ;

000c ;Puts a single char (byte value) on serial output

000c ;Call with char to send in A register. Uses B register

000c 47 write_char: ld b,a ;store char

000d db 03 write_char_loop: in a,(3) ;check if OK to send

000f e6 01 and 001h ;check TxRDY bit

0011 ca 0d 00 jp z,write_char_loop ;loop if not set

0014 78 ld a,b ;get char back

0015 d3 02 out (2),a ;send to output

0017 c9 ret ;returns with char in a

0018 ;

0018 ;Subroutine to write a zero-terminated string to serial output

0018 ;Pass address of string in HL register

0018 ;No error checking

0018 db 03 write_string: in a,(3) ;read status

001a e6 01 and 001h ;check TxRDY bit

001c ca 18 00 jp z,write_string ;loop if not set

001f 7e ld a,(hl) ;get char from string

0020 a7 and a ;check if 0

0021 c8 ret z ;yes, finished

0022 d3 02 out (2),a ;no, write char to output

0024 23 inc hl ;next char in string

0025 c3 18 00 jp write_string ;start over

0028 ;

0028 ;Binary loader. Receive a binary file, place in memory.

0028 ;Address of load passed in HL, length of load (= file length) in BC

0028 db 03 bload: in a,(3) ;get status

002a e6 02 and 002h ;check RxRDY bit

002c ca 28 00 jp z,bload ;not ready, loop

002f db 02 in a,(2)

0031 77 ld (hl),a

0032 23 inc hl

0033 0b dec bc ;byte counter

0034 78 ld a,b ;need to test BC this way because

0035 b1 or c ;dec rp instruction does not change flags

0036 c2 28 00 jp nz,bload