Difference between revisions of "ANTA 64K Memory Expansion"

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== Technical ==
 
== Technical ==
  
−
* Uses port &F8F8, &FADD and centronics strobe.
+
* Uses port &F8F8 to latch data (read/write)
−
* Data is read one byte at a time using &F8F8
+
* Uses memory address to define where in 64KB ram to read/write.
−
* Data is written one byte at a time using &F8F8.
+
 
* NOT Dk'Tronics compatible.
 
* NOT Dk'Tronics compatible.
 
* More like a ram disc
 
* 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:
 
* 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
 
PBUFF
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PEEK
 
PEEK
 
POKE
 
POKE
−
SCREENCOPY
 
 
SCREENSWAP
 
SCREENSWAP
 
BSAVE
 
BSAVE

Revision as of 09:51, 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

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