Difference between revisions of "ANTA 64K Memory Expansion"

Revision as of 08:59, 5 November 2015

A 64KB memory expansion by MHT Ingenieros.

Pictures

• 

  Unit front

• 

  Unit back

• 

  PCB top

• 

  PCB bottom

Technical

• Uses port &F8F8 to latch data (read/write)
• Uses memory address to define where in 64KB ram to read/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 NBUFF PEEK POKE SCREENSWAP BSAVE BLOAD CSAVE CLOAD OPEN GET CLOSE PUT MKILL MCAT MRENAME FREDSK RAMDSK CC

ROM

• MHT Ingenieros ANTA 64K.3 ROM (zipped .ROM file)