Download You are asked to interface a 32 KB RAM to an 8086

College of Computer and Information Sciences
Department of Computer Engineering
First Semester 1428-1429H
Homework #3
CEN 433: Digital Systems Design
-----------------------------------------------------------------------------------------------------------(30 Points) Answer the following questions:
You are asked to interface an additional 256 KB RAM and 128 KB EPROM to an 8086-2
microprocessor in the minimum mode. Answer all of the following questions:
(a) ( 4 Points) The 256 KB RAM consists of four RAM chips. If the starting address
of the RAM is 00000H, fill-in the boundary addresses on the following memory
map.
64k x 8
RAM 1
128k × 8
RAM 4
32k x 8
RAM 2
32k x 8
RAM 3
(b) (4 Points) The 128 KB EPROM consists of three EPROM chips. If the last
address of the EPROM is FFFFFH, fill-in the boundary addresses on the
following memory map.
64k × 8
EPROM 3
32k x 8
EPROM1
32k x 8
EPROM2
(c) (2 Points) The memory space of 8086-2 microprocessor is divided into 2
segments. One of them is assigned completely to the 256 KB RAM and the other
is assigned completely to the 128 KB EPROM. Show the basic and foldback
blocks for each segment and their boundary addresses.
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(d) (8 Points) Using ORCAD, design the decoding circuit based on the above
assumptions to generate chip selects for the RAM chips (RAM1CS/,
RAM2CS/, RAM3CS/, and RAM4CS/) and for the EPROM chips
(EPROM1CS/, EPROM2CS/, and EPROM3CS/).
(e) (6 Points) Compute the propagation delay for the RAM and EPROM chip
select signals.
(f) (6 Points) Interface these five RAM chips and three EPROM chips to the
buffered 8086-2 system according to the above mapping.
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