Rev. 1.0, 09/02, page 49 of 568
3.2.2
System Control Register (SYSCR)
SYSCR is an 8-bit readable/writable register that selects saturating or non-saturating calculation
for the MAC instruction, selects the interrupt control mode and the detected edge for NMI, and
enables or disables on-chip RAM.
Bit Bit
Name Initial
Value
R/W Descriptions
7 MACS 0
R/W MAC
Saturation
Selects either saturating or non-saturating calculation
for the MAC instruction.
0: Non-saturating calculation for the MAC instruction
1: Saturating calculation for the MAC instruction
6
0
Reserved
This bit is always read as 0 and cannot be modified.
5
4
INTM1
INTM0
0
0
R/W
R/W
These bits select the control mode of the interrupt
controller. For details of the interrupt control modes,
see section 5.6, Interrupt Control Modes and Interrupt
Operation.
00: Interrupt control mode 0
01: Setting prohibited
10: Interrupt control mode 2
11: Setting prohibited
3
NMIEG
0
R/W
NMI Edge Select
Selects the valid edge of the NMI interrupt input.
0: An interrupt is requested at the falling edge of NMI
input
1: An interrupt is requested at the rising edge of NMI
input
2,
1
All
0
Reserved
These bits are always read as 0 and cannot be
modified.
0 RAME 1
R/W RAM
Enable
Enables or disables on-chip RAM. The RAME bit is
initialized when the reset status is released.
0: On-chip RAM is disabled
1: On-chip RAM is enabled
Summary of Contents for H8S/2627
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