42
4.2
Memory
configurations
4.2.1 Memory map for IPL state
When the
IPL (Initial Program Loader) in the
boot
ROM
starts,
the
file (cassette tape file or
diskette file)
is
read automatically. The memory
at
this time is
as
shown in
the
map in FIGURE 4.2.
Address
$0000~-------------c--~,
$07FF
t----------,
$8000
empty
RAM(I)
32k
bytes
Initial
Program Loading
FIGURE
4.2
Memory map for IPL operation
Program File
Boot
ROM
addresses range from $0000 to $07FF. This IPL loads a system program (for example,
BASIC interpreter,
PASCAL
or
Assembler)
to
the
head
of
RAM
(I)
(the standard 32k-byte package).
In this state, the
RAM
(I) addresses range from $8000
to
$FFFF.
After loading,
the
addresses are
inverted from the
IPL state
to
the
normal state so
that
the system program is activated.
When
the
IPL RESET switch (one
of
two reset switches provided
on
the
back
of
the
MZ-80B)
is
pressed, IPL is performed in
the
same manner
as
described above.
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