Reading Digital Design and Computer Architecture? Build its circuits live
Digital Design and Computer Architecture, by Sarah L. Harris and David Harris, is a university textbook that carries one thread from logic gates to a working processor. Its chapters run from From Zero to One through combinational and sequential logic design, hardware description languages and digital building blocks to architecture, microarchitecture and memory systems, with an I/O chapter online. The RISC-V Edition, published by Elsevier in 2021, designs single-cycle, multicycle and pipelined RISC-V processors and gives its designs in both SystemVerilog and VHDL; the authors' site also lists a second edition and an ARM edition. This page maps each chapter to circuits and lessons you can try live in digiwleea's free browser lab, as a hands-on companion to the reading.
What the book does best
It carries a single design thread all the way from a gate to a pipelined processor, and it does so the way hardware is built in practice: in HDLs, with SystemVerilog and VHDL side by side, in simulation and on real boards. The authors' companion site (pages.hmc.edu/harris/ddca/) has lecture slides, lab projects, HDL code, solutions to the odd-numbered exercises, videos and a RISC-V visualizer, and two companion edX courses are free to view, with paid registration for graded work or a certificate. (digiwleea is an independent project, not affiliated with the authors or Elsevier.)
Where digiwleea helps
A textbook figure stands still, and HDL runs in a tool you install. digiwleea is a visual, switch-level simulator in the browser: you build gates from CMOS transistors, then wire adders, multiplexers, decoders, latches, flip-flops, counters and memory, and watch every wire as you flip the inputs, with each part checked against its truth table. That makes it a quick place to get a feel for a chapter's circuits before you write them in HDL. Two honest limits: digiwleea's CPU is a small 8-bit teaching processor with its own instruction set, not RISC-V, and the lab is schematic-based. It can export a circuit to Verilog or VHDL and import a combinational subset of VHDL, but it does not replace an HDL simulator or an FPGA board.
| Digital Design and Computer Architecture | digiwleea | |
|---|---|---|
| Format | A textbook (print and e-book) with a companion site | A browser lab, theory lessons and a guided course |
| How circuits are described | Schematics, SystemVerilog and VHDL | Schematics you wire, from transistors up |
| Processor | Single-cycle, multicycle and pipelined RISC-V | A small 8-bit CPU you build and program |
| Checks your work | Exercises, with odd-numbered solutions online | Every part checked against its truth table |
| Price | The book is paid; the companion site is free | Free lab and Act I; Premium for the full course |
Chapter by chapter: what to try live
The chapter titles are the publisher's (RISC-V Edition); next to each, the digiwleea lessons and live circuits on the same topics:
- 1. From Zero to One. Binary, hexadecimal and two's complement; gates from transistors in the NMOS switch and CMOS lessons, the MOSFET simulator and CMOS power.
- 2. Combinational Logic Design. Boolean algebra, sum of products and product of sums, Karnaugh maps (and the K-map solver, up to 6 variables), multiplexers, decoders, hazards and timing.
- 3. Sequential Logic Design. The SR latch, D latch and D flip-flop, registers, finite state machines (live: a turnstile and a sequence detector) and metastability.
- 4. Hardware Description Languages. Free lessons on Verilog and VHDL, including sequential Verilog and VHDL processes; circuits you build can be exported to either language.
- 5. Digital Building Blocks. Ripple-carry and carry-lookahead adders, the 4-bit ALU, the barrel shifter, multipliers, counters, shift registers, RAM, ROM and PLAs and FPGAs.
- 6. Architecture. Machine code, assembly, addressing modes and branches and loops, on digiwleea's own 8-bit instruction set.
- 7. Microarchitecture. The datapath, control unit, microcode, pipelining and performance; run a CPU step by step in the CPU simulator.
- 8. Memory Systems. The memory hierarchy, caches and virtual memory.
- 9. I/O Systems (online). Memory-mapped I/O.
No sign-up is needed to start: open the lab and place your first transistor, or read the free theory course. The account (and the AI tutor) are optional.
See for yourself: build a logic gate from transistors in the simulator, then follow the path from sand to an 8-bit CPU.
Open the digiwleea lab →Frequently asked
Is there an online simulator for Digital Design and Computer Architecture?
The book's designs are written in SystemVerilog and VHDL, which run in HDL simulators, and the authors' companion site has labs, HDL code and a RISC-V visualizer. To try the gate-level circuits of the early chapters interactively, with nothing to install, a browser logic simulator such as digiwleea works well alongside it.
Does digiwleea use SystemVerilog or VHDL?
You build circuits as schematics, from transistors and gates up. digiwleea has free lessons on Verilog and VHDL, can export circuits to either, and imports a combinational subset of VHDL, but it does not simulate HDL code directly.
Is digiwleea's CPU a RISC-V processor?
No. It is a small 8-bit teaching CPU with its own short instruction set, built from the parts you make in earlier levels. The ideas carry over to the book's processor chapters: instructions as bits, a datapath, control signals, and fetch, decode and execute.
Is Digital Design and Computer Architecture good for beginners?
It is written for university courses and starts from the basics, number systems and gates, so a motivated beginner can follow it. If you want a gentler, hands-on start first, digiwleea's free lessons begin with a single transistor switch.