CSC 311 Practice Problem Set #3
- List and count the pins you would expect a 4-bit adder chip to have.
- Imagine a 16-bit ALU made of sixteen 1-bit ALUs. The 1-bit ALU has an add time fo 10ns. If there is an additional 1ns delay for propagation from one ALU to the next, how long would it take for the result of a 16-bit add to appear?
- Consider the 4 x 3 memory circuit. It uses 22 AND gates and three OR gates. If we expanded the circuit to 256 x 8, how many of each would we need?
- Describe the binary instruction that the 1-bit ALU needs to
accomplish the operation of B plus 1. Describe why this instruction
accomplishes the desired operation.
- Using the 8-bit memory chip, describe what pins should
be connected to 5 volts (the power rail) to store the following 8-bit
number: 00101011. Assume that the higher the pin number, the higher the
order of the bit. (Hint: don't forget that the clock is the enable line)
- Using the 4 x 3 memory circuit, describe all the input signals (data and
control) required to store (write) the 3-bit number 110 at Word 1 address.
- Using the 4 x 3 memory circuit, describe all the input and output signals (data
and control) of an operation that loads (reads) a 3-bit number from the Word
2 address.
- With the 4 x 3 memory circuit, why are the buffers a good idea rather than just
plain gates? In your answer, describe why gates might be a bad idea here.
- Imagine we have a memory clip (a circuit board with memory chips) that has
8 memory chips like the 16Mbit DRAM chip. Assume that this clip constitutes the
entire memory (RAM) in the system. Now describe what a typical memory
address would look like in binary and how that address translates to signals
on the clip and for each chip.
Solutions to these problems are available here.