Zilog Z80230 - Manual (Page 247)

SCC/ESCC
User Manual
UM010903-0515 Application Notes
240
Table lists a “macro” to enable the Z180 to use the Z80 ® Assembler, as well as register defini-
tions.
;external/status interrupt
service routine
ext_stat: ld a,10h
out (scc_cont),a ;reset ext/stat int
in a,(scc_cont) ;read stat
and 00100000b ;mask off bits other than /cts
rra ;shift into D0 loc
rra
rra
rra
rra
set 1,a ;set interrupt fla
ld b,a ;save it
ld a,38h
out (scc_cont),a ;reset highest ius
ei ;enable int
ret ;return from int
;initialization data table for scc
;table format - register number, then value for the register
;and ends with 0ffh - since scc doesn’t have
;register 0ffh...
scctab: db 09h ;select WR9
if scc_a
db 10000000b ;ch a reset
else
db 01000000b ;ch b reset
endif
db 0eh ;select WR15
db 20h ;only enable /cts int
db 01h ;select WR1
db 00000001b ;enable ext/stat int
db 10h ;reset ext/stat int
db 10h ;twice
db 09h ;select WR9
db 08h ;mie, vect not incl. stat
db 0ffh ;end of table
;interrupt vector table
org inttest + 100h
sccvect: dw ext_stat
.block 100h ;reserve area for stack
top_of_sp:
end