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The XSOC Project Version Beta 0.93 README

Copyright (C) 1999, 2000, Gray Research LLC.  All rights reserved.
The contents of this file are subject to the XSOC License Agreement;
you may not use this file except in compliance with this Agreement.
See the LICENSE file.

Dear intrepid student, educator, hobbyist, or researcher,

Thank you for your interest in the XSOC Project.  The XSOC Project
is an unsupported collection of experimental hardware and software
designs and specifications, cited in the Circuit Cellar magazine
series, "Building a RISC System in an FPGA", and providing an
example for the noble purpose of teaching computer design.

XSOC consists of the XSOC System-on-a-Chip design, including the
xr16 RISC processor core, and an on-chip bus and peripherals.
It is accompanied by a port of the lcc4.1 retargetable C compiler
that targets xr16, and a simple xr16 assembler and simulator.

Please be sure to carefully review the XSOC License Agreement
(see the LICENSE file).

Also be sure to visit for the latest news
and to check that you have the current version of the XSOC Project.
This is version Beta 0.93.

To begin, read the Getting Started Guide (doc\started.pdf).

If you do try the XSOC Project, please let us know what you think
of it, either by sending a message to or
by filling out the Survey and sending it to

I do hope you enjoy working with the XSOC Project and that it inspires
you to pursue further hands-on study of computer design and FPGAs.

Jan Gray
President, Gray Research LLC


The XSOC Project distribution consists of these files and directories.

1. Documents
    LICENSE: XSOC License Agreement
    README: this file
    FAQ: frequently asked questions about XSOC
    contrib: list of third party contributions
    survey: XSOC User Survey 1.0
    doc\started.pdf: Getting Started Guide
    doc\xspecs.pdf: Various xsoc/xr16 specifications
    doc\schematics.pdf: A Tour of the XSOC/xr16 Schematics
    doc\xsoc-talk.pdf: Slides of a talk on FPGA CPUs and XSOC/xr16

2. Project Issues
    issues\issues: issues database
    issues\issues-list: issues list summary
    issues\issues-howto: how to report new issues

3. Tools
    lcc-xr16\: C compiler for xr16
    src\xr16\: xr16 assembler and simulator
    src\lfsr\: linear feedback shift register counter generator

4. Schematics Design
    xsoc.pdf(*), xsoc\: XSOC/xr16 Foundation 1.5 XSOC 1.0 design

5. Verilog Design
    xsocv.pdf(*), xsocv\: XSOC/xr16 1.0 Verilog design

6. Configuration Bitstreams
    Schematics version
        xsoc\xsoc-05xl-1.2-093.bit:    12   MHz XSOC 1.0 for XS40-005XL v1.2
        xsoc\xsoc-05xl-1.3-093.bit:    12.5 MHz XSOC 1.0 for XS40-005XL v1.3
        xsoc\xsoc-05xl-1.4-093.bit:    12.5 MHz XSOC 1.0 for XS40-005XL/+ v1.4
        xsoc\xsoc-10xl-1.2-093.bit:    12   MHz XSOC 1.0 for XS40-010XL v1.2
        xsoc\xsoc-10xl-1.3-093.bit:    12.5 MHz XSOC 1.0 for XS40-010XL v1.3
        xsoc\xsoc-10xl-1.4-093.bit:    12.5 MHz XSOC 1.0 for XS40-010XL/+ v1.4
    Verilog version
        xsocv\xsocv-05xl-1.3-093.bit:  12.5 MHz XSOC 1.0 for XS40-005XL v1.3
        xsocv\xsocv-05xl-1.4-093.bit:  12.5 MHz XSOC 1.0 for XS40-005XL/+ v1.4
        xsocv\xsocv-10xl-1.3-093.bit:  12.5 MHz XSOC 1.0 for XS40-010XL v1.3
        xsocv\xsocv-10xl-1.4-093.bit:  12.5 MHz XSOC 1.0 for XS40-010XL/+ v1.4

7. Demos
    demos\fib.c: Fibonacci demo source
    demos\sim.s: simulator preamble assembly source
    demos\end.s: simulator epilog source
    demos\gr.c: Graphics demo source
    demos\glyphs.c: Glyphs (font) table source
    demos\makeglyphs.c: Build glyphs.c source

8. Tests
    tests\: xr16 instruction set test suite

(*) not an Acrobat PDF document.  Unfortunately Foundation projects
are also given the .pdf filename extension.


1.  Through the XSOC files, most email addresses have been camoflaged
    ( -> or foo to help prevent
    spammers from scrubbing email addresses from the project or the
    web site.
You can’t perform that action at this time.