ALU 101 case studies
ALU 101 · Put your knowledge to work in context.
ALU 101 is a foundational credential covering the arithmetic logic unit - the circuit block at the center of every processor that performs integer arithmetic and bitwise operations. It suits students in computer engineering, computer science, or digital electronics who have completed introductory logic design and want to demonstrate that they understand how data is represented, manipulated, and routed inside a CPU datapath. The ALU 101 case studies are 5 cases and about 3,175 words.
1Two's Complement Overflow in a Saturating Accumulator
A 12-bit signed accumulator sums 8-bit signed samples. The designer claims that because each sample fits in 8 bits and the accumulator is 12 bits wide, overflow is impossible for any run of fewer than 16 samples.
579 words, about 3 min2Karnaugh Minimization Versus a Cost-Driven Implementation
A 4-input function F(A,B,C,D) is specified by minterms {0,1,2,5,8,9,10,13} with don't-cares at {6,7,14,15}. A junior engineer runs a Karnaugh map, gets a two-level sum-of-products with three product terms, and declares it optimal.
644 words, about 3 min3Pipeline Hazard in a Single-Cycle-to-Pipelined ALU Datapath
A simple datapath executes ADD, SUB, AND, OR, and a conditional branch. Originally single-cycle.
653 words, about 3 min4Shift-and-Add Multiplier Sign Handling
An 8-bit shift-and-add multiplier is built for unsigned operands: it accumulates partial products, shifting the multiplier right each step and the multiplicand left. A designer reuses it for signed two's-complement operands by simply feeding the bit patterns in and ignoring the sign, claiming 'the low 8 bits of the product are the same either way.' Test vectors: (-3) x (5) and (-3) x (-5), expected 8-bit two's-complement products.
649 words, about 3 min5Control Signal Sequencing Under a Stuck Flag
A microcoded control unit drives an ALU with signals ALUop[2:0], a register-file write enable RegWr, and a branch-taken signal BrTaken. The ALU sets a zero flag Z and a carry flag C.
650 words, about 3 min