Changes
/* Technical */
== Technical ==
* Uses port &F8F8, &FADD and centronics strobe.to latch data (read/write)* Data is Uses memory address to define where in 64KB ram to read one byte at a time using &F8F8* Data is written one byte at a time using &F8F8/write.
* NOT Dk'Tronics compatible.
* More like a ram disc
to write:
LD BC,&F8F8 ;; ram data access
LD A,&34 ;; value to write
LD DE,&4000 ;; where in extra ram to read (0-&ffff)
DI
OUT (C),A ;; latch data for ram
LD A,(DE) ;; perform write into ram
EI
to read:
LD BC,&F8F8
ld de,&4000
di
in a,(c)
ld a,(de) ;; read value from extra ram
ei
each access to the I/O port must be followed by a memory read operation.
ROM uses single byte reads such as LD A,(DE)
* ROM has commands:
|SCREENCOPY,<ram page>,1
copy screen at &c000 to ram page.
numbers can't be 0 or greater than or equal to 6.
PBUFF
PEEK
POKE
SCREENSWAP
BSAVE
