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A CPU that aims to be binary compatible with the 8086 ISA, focused on optimisation and flexibility.
102 Commits 2 Branches 4 Tags 1.8 MiB
Verilog 66.9%
Makefile 9.9%
Assembly 9.4%
Shell 6.9%
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(Tim) Efthimis Kritikos df342467c7 Saved a clock cycle from microcode starts and added info in decode to allow saving a cycle on almost every instruction
2023-05-13 13:45:15 +01:00
boot_code Improved DOS char print code 2023-03-14 07:20:30 +00:00
readme_files Added a background to the high level diagram picture to make it viewable on dark mode 2023-05-03 17:48:24 +01:00
system Saved a clock cycle from microcode starts and added info in decode to allow saving a cycle on almost every instruction 2023-05-13 13:45:15 +01:00
.gitignore Wrote a more complete testbench for verilator, switched from lx2 to fst and fixed cpu clock frequency calculation 2023-03-05 00:10:55 +00:00
8086_documentation.md Overhauled cpu frontend. Made memory byte addressable (necessary), cleaned up state machine and fixed small bug with MOV 2023-03-03 06:29:06 +00:00
common.mk Added partial support for the software interrupt INT instruction 2023-03-08 07:26:28 +00:00
COPYING Properly licensed the project and run it through aspell 2023-02-13 16:49:17 +00:00
gtkwave_savefile.gtkw Improved parallelism 2023-05-13 10:52:44 +01:00
Makefile Added the OUT instruction to be able to properly address I/O and moved printing logic to a device on the I/O space. Also added IRET which is basically just a RET in this case 2023-03-09 06:03:13 +00:00
README.md Made execute unit run in parallel with everything else. Still not parallel for most of the time though 2023-05-13 06:51:35 +01:00

README.md

9086 logo

A CPU that aims to be binary compatible with the 8086 and with as many optimisations as possible

Progress

  • 8086
    • Executing code
    • Is Turing complete
    • Can boot up MS-DOS / FreeDOS
    • Is completely binary compatible
    • Is pipelined
    • Is Out of Order
    • Is superscalar
    • Has been successfully synthesized

Simulating it

Both Verilator and Icarus Verilog can be used for simulation. You can select which one you want with the SIM variable on common.mk Specifically this list shows the software needed and the versions used during development (other versions should work as well)

  • Icarus Verilog : version 11.0 OR (preferred) Verilator : 5.008
  • bin86 : 0.16.21
  • GNU Make : 4.4.1
  • xxd : 2022-01-14
  • POSIX coreutils : GNU coreutils 9.3

After that you can run make on the top level directory and it should build everything and start the simulation

High level design overview

9086 logo

License

All parts of this project are licensed under the GNU General Public License version 3 or later

Version names

The version name consist of three numbers:

  1. The CPU that this version aims to be compatible with
  2. The specific milestone
  3. Patch level

For example v1.3.2 aims to support 80186 code, is on the fourth milestone and has 2 bug fixes since the milestone was reached.