NEC PD754144 - Manual (Page 104)

CHAPTER 6 PERIPHERAL HARDWARE FUNCTION
104 User’s Manual U10676EJ3V0UM
Figure 6-14. Block Diagram of Clock Generator (2/2)
(b)
µPD754244 Crystal/Ceramic Oscillation
X1
X2
System
clock
oscillator
Oscillation stops
1/2 1/4 1/16
f X
Divider
1/4 Φ
HALT F/F
S
R Q
S
R
Q
STOP F/F
PCC0
PCC1
PCC2
PCC3
PCC2,
PCC3
clear
HALT Note
STOP Note
Wait release signal from BT
PCC
4
· Basic interval timer (BT)
· Timer counter
· INT0 noise eliminator
1/1 to 1/4096
· CPU
· INT0 noise
eliminator
Divider
Selector
Internal bus
Reset signal
(selectable by mask option)
Standby release signal from
interrupt controller
Note Instruction execution
Remarks 1. f X : System clock frequency
2. Φ = CPU clock
3. PCC: Processor Clock Control Register
4. One clock cycle (t
CY
) of the CPU clock is equal to one machine cycle of the instruction.