Reading Tanenbaum's Structured Computer Organization? Build it live
Structured Computer Organization, by Andrew S. Tanenbaum (6th edition, Pearson, 2012), explains a computer as a stack of levels, each built on the one below: digital logic, microarchitecture, instruction set architecture, operating system and assembly language. Its contents run from gates and Boolean algebra, basic logic circuits, memory, CPU chips and buses (section 3), through an example microarchitecture, the Mic-1, that implements the IJVM instruction set with microinstructions, and faster designs from the Mic-2 to the pipelined Mic-4 (section 4), to the ISA level, virtual memory, assembly language and on-chip parallelism, with the Intel Core i7, the TI OMAP4430 and the Atmel ATmega168 as running examples. This page maps those levels to lessons and live circuits you can try in digiwleea's free browser lab, as a hands-on companion to the reading.
What the book does best
Its level-by-level structure makes the whole machine understandable: you see why each layer exists and how it hides the one below. The microarchitecture chapter is unusually concrete, walking a real data path and microprogram (the Mic-1 running IJVM) step by step and then speeding it up with prefetching and pipelining, and the three example chips keep it tied to real hardware. (digiwleea is an independent project, not affiliated with Pearson or the authors.)
Where digiwleea helps
The book's lowest level is gates; digiwleea starts one level lower, at the transistor, and lets you build upward yourself. In the browser you wire CMOS transistors into gates, then the circuits of the digital logic level (adders, latches, flip-flops, registers, memory, buses) and finally a small 8-bit CPU that runs a stored program, plus the assembly language behind it, with every part checked against its truth table. It is far smaller than the Mic-1 or the Core i7, but you can watch every wire of it.
| Structured Computer Organization | digiwleea | |
|---|---|---|
| Format | A textbook (print and e-book) | A browser lab, theory lessons and a guided course |
| Lowest level | Gates and Boolean algebra | CMOS transistors |
| Example machine | The Mic-1 microarchitecture running IJVM, plus real CPUs | A small 8-bit CPU you build and program |
| Control | Microprogrammed (the Mic-1), then pipelined designs | Hardwired and microprogrammed control, as live circuits |
| Price | Paid textbook | Free lab and Act I; Premium for the full course |
Level by level: what to try live
The section titles are the 6th edition's; next to each, the digiwleea lessons and live circuits on the same topics:
- 3.1 Gates and Boolean Algebra. Gates from transistors in the CMOS inverter and CMOS NAND, Boolean algebra, circuit equivalence with De Morgan's laws, and practice with the Boolean algebra problems.
- 3.2 Basic Digital Logic Circuits. Multiplexers, decoders, comparators, adders, the ALU and the shifter, and clocks.
- 3.3 Memory. The SR and D latches, flip-flops, registers, RAM and ROM, and the memory simulator.
- 3.4 CPU Chips and Buses, 3.7 Interfacing. A shared bus with tri-state buffers, the MAR and MDR, and address decoding with the 74LS138.
- 4.1 An Example Microarchitecture. The data path and microinstructions: the datapath and microcode lessons and a live microprogrammed control unit, next to a hardwired one.
- 4.2 An Example ISA: IJVM. Stacks in hardware: the live stack and stack pointer.
- 4.4 and 4.5: speed. Pipelining, cache memory and a live direct-mapped cache.
- 5.1 The ISA Level, 7.1 Assembly Language. Machine code, addressing modes and assembly, with the instruction register and the CPU simulator.
- 6.1 Virtual Memory. The virtual memory lesson.
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.
More comparisons: Books, courses and projects
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 a simulator for Tanenbaum's Mic-1?
Mic-1 and IJVM simulators exist as separate programs. To see the gate-level pieces the Mic-1 is built from (registers, an ALU, a shifter, a control store), digiwleea runs them as live circuits in the browser, including a small microprogrammed control unit.
What are the levels in Structured Computer Organization?
The book builds a computer as layers: the digital logic level, the microarchitecture level, the instruction set architecture level, the operating system level and the assembly language level, each implemented by the one below it.
Is digiwleea's CPU like the Mic-1?
It is much smaller, an 8-bit accumulator machine with its own instruction set rather than a stack machine running IJVM, but it is built from the same kinds of parts, and its control can be studied in both hardwired and microprogrammed form.
Should I read Tanenbaum or Patterson and Hennessy?
Both are standard. Tanenbaum organizes the machine as levels and includes a microprogrammed example; Patterson and Hennessy centers on one instruction set (RISC-V, MIPS or ARM) and its pipelined processor. This site has a Patterson and Hennessy companion page too.