HD6412320 RENESAS [Renesas Technology Corp], HD6412320 Datasheet - Page 72

• Manufacturer Part Number: HD6412320
• Description: Renesas 16-Bit Single-Chip Microcomputer H8S Family H8S-2300 Series
• Manufacturer: RENESAS [Renesas Technology Corp]

Section 2 CPU
Free area
SP (ER7)
Stack area
Figure 2.6 Stack
2.4.3
Control Registers
The control registers are the 24-bit program counter (PC), 8-bit extended control register (EXR),
and 8-bit condition-code register (CCR).
(1) Program Counter (PC)
This 24-bit counter indicates the address of the next instruction the CPU will execute. The length
of all CPU instructions is 2 bytes (one word), so the least significant PC bit is ignored. (When an
instruction is fetched, the least significant PC bit is regarded as 0.)
(2) Extended Control Register (EXR)
This 8-bit register contains the trace bit (T) and three interrupt mask bits (I2 to I0).
Bit 7—Trace Bit (T): Selects trace mode. When this bit is cleared to 0, instructions are executed
in sequence. When this bit is set to 1, a trace exception is generated each time an instruction is
executed.
Bits 6 to 3—Reserved: These bits are reserved. They are always read as 1.
Bits 2 to 0—Interrupt Mask Bits (I2 to I0): These bits designate the interrupt mask level (0 to
7). For details, refer to section 5, Interrupt Controller.
Operations can be performed on the EXR bits by the LDC, STC, ANDC, ORC, and XORC
instructions. All interrupts, including NMI, are disabled for three states after one of these
instructions is executed, except for STC.
Rev.6.00 Sep. 27, 2007 Page 42 of 1268
REJ09B0220-0600