System Description; Memory Map; At Power On; Bootstrap - Sharp MZ-700 Service Manual

4. SYSTEM DESCRIPTION
4-1. Memory map
a) At power on
$0000
$1000
$1200
$0000
$0800
$EOoo
$FOoo
MONITOR
(ROM)
MONITOR WORK
SYSTEM
and
TEXT AREA
(DRAM)
V·RAM<CHARACTER>
(SRAMI
V·RAM<COLORDATA>
(SRAMI
KEY and TIMER PORT
FLOPPY CONTROLLER
Enable
$0000
$1000
$0000
SYSTEM (DRAM)
and
TEXT AREA
SYSTEM
and
TEXT AREA
(DRAM)
Disable
• Shown above is the memory map at the time of power
on.
VRAM
contents from$DOOO to $DFFF differ from
the MZ·80K.
• The monitor (ROM) has the same entry point as that of
the MZ·80K.
b) Bootstrap (loading of system program)
$0000 $0000
MONITOR
Ir--
(ROfv\)
1'-
SYSTEM
$1000
LOAD
SYSTEM
$7EOD
Boot PROGRAM ~
' 1 1
$0000
$0000
V·RAM
V·RAM
$EOoo
KEY and TIMER PORT
SYSTEM
Eneble
Disable
• With the input of the LOAD command of the monitor,
the BASIC loading program is transferred to the system
area composed of the RAM and starts to bootstrap.
(Only the cassette tape is subject to bootstrapping in
this case).
4
• Boot command: L
• With the entry of the boot command
L,
only the tape
loading program is transferred to the system area and the
system program is loaded to the system area designated
in the DRAM.
NOTE: The boot program shown in the figure is the
program loaded from the tape and is not the
program from the monitor (ROM).
c) System initiation
$0000
$1000
MONITOR
(ROM)
.$0000 , - - - - - - - ,
V·RAM
V·RAM
$Eooo
I--KE-Y-ond-TI-M-ER-P-OR-T-l
:$Fooo
1 - - - - - - - - 1
Disable
$0000 , - - - - - ,
SYSTEM
$1000 ----------------------
$0000 ---------------------------
Enable
• The above memory map is valid upon completion of
system program loading.
• The system program is programmed to switch the
memory depending upon what is accessed, VRAM,
keyboard, or timer.
d) At the time of manual reset
$0000
$1000
MONITOR
(ROM)
$0000
I
SYSTEM
$1000
~-----~
SYSTEM
$0000
$0000 , - - - - - - - ,
V·RAM
V-RAM
$EOoo
KEY and TIMER PORT
SYSTEM
$FOoo
Enable
Disable