OMEN Bravo

As-easy-as-possible, but still expandable single board computer with 65C02 CPU.

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Do you know the OMEN Alpha? Bravo is a 65C02-based brother of this SBC. It was made to educational purposes, so it is kept as simple as possible.


  • 65C02 CPU by Rockwell operated at 3.6864 MHz (You can use the WDC version too)
  • 32 kB of static RAM
  • 8 kB of EEPROM
  • ACIA 6551 for serial port, provides serial communication up to 19.200 Bd
  • VIA 6522 for parallel port and counter/timer functions
  • A "System Bus Connector" with data bus, address lines, control lines and decoded I/O addresses.


Eagle Schematics

sch - 1.08 MB - 11/10/2018 at 14:38



Eagle board

brd - 341.49 kB - 11/10/2018 at 14:38




Portable Network Graphics (PNG) - 214.13 kB - 11/10/2018 at 14:38


Portable Network Graphics (PNG) - 65.25 kB - 11/10/2018 at 14:38


  • 1 × R65C02 Microprocessors, Microcontrollers, DSPs / Microprocessors (MPUs)
  • 1 × R6551 Connectors and Accessories / Connector Accessories
  • 1 × 3.6864 crystal
  • 1 × push button
  • 6 × 100 nF capacitor

View all 13 components

  • Become a supporter!

    Martin Maly08/30/2019 at 11:43 0 comments

    new support page on Patreon is available now. Check your tiers and rewards...

  • Issue 3, Issue 4

    Martin Maly11/10/2018 at 14:33 0 comments

    Issue 3 added the VIA chip - Versatile Interface Adapter R6522. It provides two serial ports, two 16bits counters / timers and a shift register for parallel-to-serial conversion and vice versa.

    Unfortunatelly, Issue 3 has an error - ground was not connected together and there were missing place for the resonant capacitor and load, so some CPUs won't work. You can solder one wire and a two parts directly to the PCB, but it is not a solution, so I designed an Issue 4 PCB with all of those bugs fixed.

  • OMEN Bravo runs BASIC

    Martin Maly10/27/2018 at 15:36 0 comments

  • Ah, the brave old 6502...

    Martin Maly09/04/2018 at 20:31 0 comments

    It seems to be totally simple, but this was my first 6502 construction I ever designed.

    So I have made a design, have prepared a PCB, the last few wires by autorouter (keep it in mind!) and have sent to fab.

    A few days ago I have connected the whole design. And then: nothing. No single tick. It was very strange... When I have removed the 7400 (RD/WR and address decoder), the oscillator worked. 7400 back, frequency: 0.

    Totally bad dream. Later I have found the one line from CPU is routed directly through the Xtal, just between its two pins. I have cursed myself. Twice.

    The second PCB version works on the first attempt. So design was right. My mistake was the autorouting. All other PCBs are now manually routered until the last via...

    (Don't worry, the piece I am selling on Tindie is the Issue 2)

View all 4 project logs

  • 1
    Solder sockets for the integrated circuits
  • 2
    Test all soldered connections
    • Test if all pins are well connected
    • Check if GND is not short connected to Vcc
    • Check if each IC has properly connected GND and Vcc
  • 3
    Solder all passive parts

    Pay attention, the Bravo contains two crystals, one for CPU,

    marked Q1 with value 3.6864, one for serial port, marked “1.8432”

View all 10 instructions

Enjoy this project?



hardrive9000 wrote 12/11/2018 at 14:39 point

Hi Martin! I must compliment you for your project. Excelent! I have a question about it and I hope you can help me. I was trying to compile cmon.a65 from your GitHub repository by executing:

ca65 --listing -DSINGLESTEP cmon.a65

And I get the following errors:

cmon.a65(24): Error: `.ENGINE' is not a recognized control command
cmon.a65(24): Error: `:' expected
cmon.a65(26): Error: `:' expected
cmon.a65(26): Error: Unexpected trailing garbage characters
cmon.a65(28): Error: `:' expected
cmon.a65(28): Error: Unexpected trailing garbage characters
cmon.a65(30): Error: `:' expected
cmon.a65(30): Error: Unexpected trailing garbage characters
cmon.a65(31): Error: `:' expected
cmon.a65(31): Error: Unexpected trailing garbage characters
cmon.a65(32): Error: `:' expected
cmon.a65(32): Error: Unexpected trailing garbage characters
cmon.a65(33): Error: `:' expected
cmon.a65(33): Error: Unexpected trailing garbage characters
cmon.a65(35): Error: `:' expected
cmon.a65(35): Error: Unexpected trailing garbage characters
cmon.a65(36): Error: `:' expected
cmon.a65(36): Error: Unexpected trailing garbage characters
cmon.a65(37): Error: `:' expected
cmon.a65(37): Error: Unexpected trailing garbage characters
cmon.a65(38): Error: `:' expected
cmon.a65(38): Error: Unexpected trailing garbage characters
cmon.a65(48): Error: `.ENDM' is not a recognized control command
cmon.a65(52): Error: `.ENDM' is not a recognized control command
cmon.a65(525): Error: `.ENDMACRO' expected

Which compiler version are you using?

Can you upload the bin file to your repo or send me the file by email?

Thanks in advance. Best regards. Greetings from Argentina!

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