18. mbits
m bits
Address
bus
m bits
2n bits
Control
bus
Data bus
RAM 2m´ 2n
Data
in/out
RAM 2
2m´ n
RAM 1
2m
´ n
Data
in/out
D
D
nbits n bits
(continued)
19.
20. Data
bus
RAM 2M ´ 8
Address
bus
21 bits
Control
bus
20 bits
EN
EN
RAM 2
1M ´ 8
RAM 1
1M ´ 8
8 bits
8 bits
8 bits
20 bits
(continued)
21.
22.
23. 1. Expand the 2Kx8 (2716) EPROM to get 2Kx16
memory size, draw the block diagram.
2. Expand the 2KX8 (2716) EPROM to get 4KX8
memory size, draw the block diagram.
3. Expand the 2KX8 (2716) EPROM to get 8KX16
memory size, draw the block diagram.
4. How many 2716 memory chip are needed for each
case of the above?
24. 0
7 15 8 0
7
Address
BUS (20 bit)
Address
BUS (20 bit)
Data BUS
(16 bit)
Data
BUS
(16
bit) (D8-D15)
(D0-D7)
1MB 512KB 512KB
Byte 0
Byte 1
Byte 2
Byte 3
Byte 4
Byte 5
Byte 0
Byte 1
Byte 2
Byte 3
Byte 4
Byte 5
19 BIT
BHE A0
25. 8086 Byte access on even address ( low)
Address bus
A19 – A1
D15 – D8 D7 – D0
____
BHE ( HIGH )
Y
Y + 1
X + 1 X
A0 (LOW)
A0 is set to 0 to enable low bank
BHE is set to logic 1 to disable high bank
Data is transferred via D0 ( LSB ) – D7 ( MSB )
26. 8086 Byte access on odd address ( high bank)
Address bus
A19 – A1
D15 – D8 D7 – D0
____
BHE ( LOW )
Y
Y + 1
X + 1 X
A0 (HIGH)
A0 is set to 1 to disable low bank
BHE is set to logic 0 to enable high bank
Data is transferred via D8 ( LSB ) – D15 ( MSB )
27. 8086 Word access on even address (lowbank)-aligned
Address bus
A19 – A1
D15 – D8 D7 – D0
____
BHE ( LOW )
Y
Y + 1
X + 1 X
Both A0 and BHE is enabled ; data transferred from both banks at same
time
Data is transferred via D0 ( LSB ) – D15 ( MSB )
Aligned and occurs in 1 bus cycle
A0 (LOW)