Datasheet

Section 2 CPU
Page 60 of 1434 R01UH0166EJ0600 Rev. 6.00
Mar 02, 2011
H8S/2633 Group, H8S/2633 F-ZTAT
TM
,
H8S/2633R F-ZTAT
TM
, H8S/2695
Free area
Stack area
SP (ER7)
Figure 2.9 Stack
2.4.3 Control Registers
The control registers are the 24-bit program counter (PC), 8-bit extended control register (EXR),
8-bit condition-code register (CCR), and 64-bit multiply-accumulate register (MAC).
(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: 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.