Typewriter User Manual

MOTOROLA MC68340 USER’S MANUAL 4- 3
.
MC68340
RELOCATABLE
MODULE
BLOCK
RAM
(TYPICAL)
$00000000
$XXXXXFFF
MBAR
($0003FF00
FC=0111)
$XXXXX000
$FFF
$07F
$000
$FFFFFFFF
NOTE: $XXXXX is the value contained in the MBAR bits BA31-BA12.
DMA
SERIAL PORTS
TIMER MODULES
SIM 40
$7BF
$780
$721
$67F
$600
$700
Figure 4-1. SIM40 Module Register Block
4.2.2 System Configuration and Protection Operation
The SIM40 allows the user to control certain features of system configuration by writing
bits in the module configuration register (MCR). This register also contains read-only
status bits that show the state of the SIM40.
All M68000 family members are designed to provide maximum system safeguards. As an
extension of the family, the MC68340 promotes the same basic concepts of safeguarded
design present in all M68000 members. In addition, many functions that normally must be
provided by external circuits are incorporated in this device. The following features are
provided in the system configuration and protection function:
SIM40 Module Configuration
The SIM40 allows the user to configure the system to the particular requirements. The
functions include control of FREEZE and show cycle operation, the function of the
CS≈
signals, the access privilege of the supervisor/user registers, the level of interrupt
arbitration, and automatic vectoring for external interrupts.
Reset Status
The reset status register provides the user with information on the cause of the most
recent reset. The possible causes of reset include: external, power-up, software
watchdog, double bus fault, loss of clock, and RESET instruction.
Frees
cale Semiconductor,
I
Freescale Semiconductor, Inc.
For More Information On This Product,
Go to: www.freescale.com
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