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The Blitz-64 Computer System

“Rethinking Systems Architecture”


Blitz-64 is a complete computer design, including machine architecture, software tools, programming language, operating system, and hardware design files, as well as documentation and additional support material. Blitz-64 is open source and free.

Features Project Datasheet
ISA Reference Card

This is Version 2.1, dated 14 December 2023

What's new? click here (Last updated 14 December 2023.)
Access to the previous version: Version 2.0

Recent Changes:
    • Changes to ISA - 14 December 2023
    • xv6 OS kernel - 14 December 2023
    • Verilog code for FPGA core - 14 December 2023
    • Documentation updates - 14 December 2023


  • ISA Reference Card (6 pages)
    A quick-start overview of the Instruction Set Architecture. pdf

  • Blitz-64: Summary of the Machine Architecture (19 pages)
    An introduction to the Instruction Set Architecture (ISA). Also comments about the overall Blitz-64 project. pdf

  • Blitz-64: Instruction Set Architecture - Reference Manual (342 pages)
    This document describes the Instruction Set Architecture (ISA) for the Blitz-64 processor core. It documents all the machine instructions as well as the assembly code notation for these instructions. pdf

  • Blitz-64: Assembler, Linker, and Object File Format (286 pages)
    This document describes the Assembler and Linker. It also describes tools "dumpobj" and "createlib" and well as the format of object, library, and executable files. pdf

  • KPL: A Kernel Programming Language (207 pages)
    This document describes the KPL programming language, which is an integral part of the Blitz-64 Computer System. KPL has many of the features in Java, C, and C++. pdf

  • KPL Syntax (18 pages)
    This document specifies the syntax of the programming language of the Blitz-64 Computer System. pdf

  • Blitz-64: Software Reference Manual (217 pages)
    This document describes the existing Blitz-64 software, including all the commonly used KPL functions. pdf

  • Blitz-64: Emulator Reference Manual (147 pages)
    This document describes the Blitz-64 virtual machine emulator. It starts with an example debugging session to illustrate the built-in debugging functionality. It also includes detailed descriptions of the commands. pdf

  • Blitz-64: Memory-Mapped I/O Devices (64 pages)
    This document specifies the peripheral devices supported at this time by the Blitz-64 emulator and by the MicroBlitz Verilog/FPGA implementation. pdf

  • MicroBlitz Overview (4 pages)
    MicroBlitz is a hardware implementation of the Blitz-64 processor core, written in SystemVerilog, which runs on an FPGA (the Terasic Cyclone V GX). pdf

  • Blitz-64: Guide to Adding New Instructions (36 pages)
    This document reviews the steps required in order to add a new instruction to the Blitz-64 ISA. pdf

  • The Goals of the Blitz-64 Project (15 pages)
    The size and complexity of modern computing systems is terrifying. A single human mind can no longer understand the machines upon which our population, economy, and future depend. Is reliance on the legacy software monoculture sustainable in the current hostile cyber environment or is speculative innovation crucial for growth and evolution? Is efficiency always the ultimate objective or, for mission-critical applications, is it wiser to emphasize simplicity, reliability, and debugging support? Blitz-64 is a radical challenge to traditional design choices, an experimental foray into unexplored regions of hardware and software design space. pdf

Additional Documentation

  • Thread Scheduling Data Structures: An Empirical Study (50 pages)
    OS kernels employ a number of algorithms to schedule threads using different data structures, such as FIFO lists, sorted linked lists, red-black trees, and multiple run queues with one per scheduling priority. What are the relative costs associated with these different approaches? A number of empirical tests were performed and the results and conclusions are reported here. pdf

  • An Overview of Unicode including ASCII and UTF-8 (21 pages)
    Unicode is introduced and explained. The ASCII character set is listed. The UTF-8 encoding is introduced and explained. pdf

  • An Overview of Floating Point Numbers (65 pages)
    An introduction to floating point; representation of single and double types; ranges; denormalized numbers; special values and special cases; rounding rules; exceptional conditions; comments on implementation. pdf

  • Copyright
    Blitz-64 is free and open. Please use it. Copyright Notice



About the Author

Harry H. Porter III, Ph.D.
Computer Science Department
Portland State University

Short Bio: click here