# Quiz 2 -- 10 April, 1995

This is an open book, open notes exam; however, the use of
calculators is forbidden. The exam is to be turned in by 8:30
PM.

## Problem 1. (15 points)

Show how to construct a 4×16 decoder out of five 2×4
decoders with enable inputs.

## Problem 2. (8 points)

How many address lines and data lines are needed for a 4M
× 8 memory?

## Problem 3. (8 points)

Convert the decimal number 185 into a binary number.

## Problem 4. (8 points)

Convert the binary number 100011101 into a decimal number.

## Problem 5. (8 points)

Convert -254 into a ten-bit two's complement binary number.

## Problem 6. (10 points)

Convert the decimal number 47.375 into a floating point number
with one sign bit, an eight-bit exponent expressed using excess-127
notation, and a 23-bit mantissa.

## Problem 7. (8 points)

Represent the following Pascal statement in register transfer
language:

IF (NOT Q) THEN S := T
ELSE IF (NOT P) THEN S := T+1

## Problem 8. (10 points)

If registers `S` and `T` have the following
values:

`S = 1010101011`
`T = 1100010110`

what are their values after each of the following RTL statements
are performed

`S <- S+T, T <- T+1`
`S <-` *shr* `T`

where *shr* is logical shift right.

## Problem 9. (15 points)

Show the hardware needed to implement the following RTL
statements for eight-bit registers `S` and `T`:

*p q* : `S <- T, T <- S + T`
*p' q* : `T <- 1`

You may use eight-bit adders, eight-bit multiplexers, eight-bit
registers and assorted logic gates in your solution.