UPD77016 NEC, UPD77016 Datasheet - Page 10

• Manufacturer Part Number: UPD77016
• Description: 16 bits/ Fixed-point Digital Signal Processor
• Manufacturer: NEC

Note 1. DA15 to DA0 pins are located on Pin No. 21 - 24, 27 - 34, 37 - 40.
Remark The state of the pins added 3S becomes high impedance when the external memory is not accessed or bus release signal
10
X/Y
DA15 - DA0
D15 - D0
MRD
MWR
WAIT
HOLDRQ
BSTB
HOLDAK
• External data memory interface
2. D15 to D0 pins are located on Pin No. 41 - 44, 47 - 54, 57 - 60.
Symbol
(HOLDAK = 0) is output.
20
Note 1.
Note 2.
17
16
6
7
18
19
Pin No.
(3S)
(3S)
(3S)
(3S)
(3S)
I/O
I/O
O
O
O
O
O
O
I
I
Memory select signal output
• 0: X memory is used.
• 1: Y memory is used.
Address bus to external data memory
•
• During the external memory is not accessed, these pins
16 bits data bus to external data memory
• External data memory is accessed.
Read output
• Reads external memory
Write output
• Writes external memory
Wait signal input
•
Hold request signal input
• Input low level when external data memory bus is
Bus strobe signal output
• Outputs low level while the PD77016 is occupying
Hold acknowledge signal output
• Outputs low level when the PD77016 permits external
keep the previous level.
These pins are set to low level; 0x0000, by reset.
They continue outputting low level until the first external
memory access.
1: No wait
0: Wait
expected to use.
external memory bus.
device to use external data memory bus.
External data memory is accessed.
Wait cycle is input when external memory is read.
Function
PD77016