Arithmetic Logic Unit $($ALU$)$ project

Objectives: To design an $8-$bit ALU

An Arithmetic unit does the following task:

$-$ Addition

$-$ Addition with carry

$-$ Subtraction,

$-$ Subtraction with borrow,

$-$ Decrement

$-$ Increment

$-$ Transfer function.

A Logic unit does the following task:

$-$ Logical AND

$-$ Logical OR

$-$ Logical XOR

$-$ Logical NOT operation.

$-$ Shift right

$-$ Shift left

The ALU circuit provides eight arithmetic operation, four logic operations, and two shift operations. Each operation is selected with the five variables $\backslash ($ S$\_\{3\},$ S$\_\{2\},$ S$\_\{1\},$ S$\_\{0\}\backslash ),$ and

Function of ALU

$\backslash$begin$\{$tabular$\}\{|$c$|$c$|$c$|$c$|$c$|$c$|$c$|\}$

$\backslash$hline S$3$ & $\backslash (\backslash$mathrm$\{$S$\}\_\{2\}\backslash )$ & S$1$ & So & $\backslash (\backslash$mathrm$\{$C$\}\_\{\backslash$text $\{$in $\}\}\backslash )$ & Result & Operation $\backslash \backslash$

$\backslash$hline $0$ & $0$ & $0$ & $0$ & $0$ & $\backslash ($ A$+$B $\backslash )$ & Addition $\backslash \backslash$

$\backslash$hline $0$ & $0$ & $0$ & $0$ & $1$ & $\backslash ($ A$+$B$+1\backslash )$ & Addition with carry $\backslash \backslash$

$\backslash$hline $0$ & $0$ & $0$ & $1$ & $0$ & $\backslash ($ A$+\backslash$bar$\{$B$\}\backslash )$ & Subtraction with borrow $\backslash \backslash$

$\backslash$hline $0$ & $0$ & $0$ & $1$ & $1$ & $\backslash ($ A$+\backslash$bar$\{$B$\}+1\backslash )$ & Subtraction $\backslash \backslash$

$\backslash$hline $0$ & $0$ & $1$ & $0$ & $0$ & A $-1$ & Decrement $\backslash \backslash$

$\backslash$hline $0$ & $0$ & $1$ & $0$ & $1$ & A & Transfer $\backslash \backslash$

$\backslash$hline $0$ & $0$ & $1$ & $1$ & $0$ & A & Transfer $\backslash \backslash$

$\backslash$hline $0$ & $0$ & $1$ & $1$ & $1$ & A$+1$ & Increment $\backslash \backslash$

$\backslash$hline $0$ & $1$ & $0$ & $0$ & x & $\backslash ($ A $\backslash$cdot B $\backslash )$ & AND $\backslash \backslash$

$\backslash$hline $0$ & $1$ & $0$ & $1$ & x & $\backslash ($ A$+$B $\backslash )$ & OR $\backslash \backslash$

$\backslash$hline $0$ & $1$ & $1$ & $0$ & x & $\backslash ($ A $\backslash$oplus B $\backslash )$ & XOR $\backslash \backslash$

$\backslash$hline $0$ & $1$ & $1$ & $1$ & X & NOTA & Complement $\backslash \backslash$

$\backslash$hline $1$ & $0$ & $0$ & x & x & LSR A & Logical Shift Right $\backslash \backslash$

$\backslash$hline $1$ & $0$ & $1$ & x & x & LSL A & Logical Shift Left $\backslash \backslash$

$\backslash$hline

$\backslash$end$\{$tabular$\}$