Memory Map For V-Ram Accessing State - Sharp MZ-80B Owner's Manual

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4.2.3 Memory map for V-RAM accessing state
Memory addresses are changed when the V-RAM is accessed. The RAM addresses in the normal
state range from $0000 to $7FFF for RAM
(1),
and from $8000 to $FFFF for RAM (II) . When the
V-RAM is accessed, addresses $DOOO to $FFFF of RAM (II) are disabled so that the V-RAM will be
access object.
This changeover is effected by A
7
of PIO . When two pages of graphic V-RAM are used, selection
of graphic pages
(I)
and (II) is made by OUT port $F4. This operation is shown in FIGURE 4.4.
Address
$0000
$7FFF
$8000
$CFFF
$DOOO
$DFFF
$EOOO
RAM I
RAM IT
(Option)
RAM IT
RAM IT
'
Addr.
Addr.
~:Switching by PIO A,
I
Addr.
I
V-RAM
, , ~ ddr.,
Character
~
/Switching
by
OUT port
$F4
Addr.
Addr.
$FFFFL_ ________
~~
V-RAM
Graphic I
(Option)
V-RAM
Graphic IT
(Option)
Page 1
Page 2
FIGURE 4.4 Switching of main memory and V-RAM ( 1)
Address switching of the V-RAM as shown above is effected by monitor subroutine PRINT or the
like.