ECE 2030 J Computer Engineering Fall 2002
4 problems, 5 pages Exam Three Solutions 21 November 2002
1
Problem 1 (3 parts, 28 points) Memory Systems
Imagine using a 16 Mbit DRAM organized as 2 million addresses of 8-bit words to build
memory systems. The following three parts consider memory systems built using this chip.
Part A (10 points) Consider a memory system organized as 16 million addresses of 16-bit words.
number of chips needed in one bank 2 chips/bank
number of banks for memory system 8 banks
number of bits in address 24 bits
memory decoder required (n to m)3-to-8 decoder
number of DRAM chips required 16 chips total
capacity (in Mbits) 256Mbits
Part B (10 points) Consider a memory system organized as 2 million addresses of 32-bit words.
number of chips needed in one bank 4 chips/bank
number of banks for memory system 1 bank
number of bits in address 21 bits
number of DRAM chips required 4 chips total
capacity (in Mbits) 64 Mbits
Part C (8 points) Consider a memory system with 3 chips per bank and a 2-to-4 memory
decoder.
number of addresses 8M addresses
size of a word 24 bits
capacity (in Mbits) 192 Mbits
Problem 2 (1 part, 12 points) Instruction Formats
Suppose a datapath has three operand busses (two source, one destination) and it has the
following I-type instruction format:
Opcode: 8 bits Destination register: 6 bits Source register: 6 bits Immediate: 12 bits
Determine the following parameters of this datapath.
maximum number of different opcodes 256
maximum number of registers in the register file 64
range of possible signed immediate values 2±K
minimum number of bits needed to specify an R-type instruction 26 bits
