Upgrading RomWBW

RomWBW firmware can be updated by ‘flashing’ the ROM.

WARNING: This process appears to be reliable, BUT if anything goes wrong it could leave the ROM corrupt and the system inoperable. In such a case the ROM would need to be reprogrammed with an EPROM programmer.

First download the required .rom file. These are available at GitHub and can also be found on the product pages of this website:

Ensure the jumper on the retro system is set to enable writing to the Flash memory chip. The retro system can be run with the Flash chip write enabled as the sequence required to write to it is unlikely to happen in normal use. However, for peace of mind, it might be best to write protect the Flash chip after the update.

Transfer the .rom file to the retro computer’s SD card or Compact Flash card using XMODEM (or similar) and then install the new firmware with the FLASH command. For example, using XMODEM and Tera Term:

  • Enter the command: xm r d:sc131.rom
  • Select File, Transfer, XMODEM, Send…
  • Select the required .rom file
  • Enter the command: flash write d:sc131.rom

Below is the terminal session for this example.

B>xm r d:sc131.rom

XMODEM v12.5 - 07/13/86
RBC, 28-Aug-2019 [WBW], ASCI

Receiving: D0:SC131.ROM
8176k available for uploads
File open - ready to receive
To cancel: Ctrl-X, pause, Ctrl-X

Thanks for the upload

B>flash write d:sc131.rom
FLASH4 by Will Sowerbutts will@sowerbutts.com version 1.2.3

Using RomWBW (v2.6+) bank switching.
Flash memory chip ID is 0xBFB7: 39F040
Flash memory has 128 sectors of 4096 bytes, total 512KB
Write complete: Reprogrammed 0/128 sectors.


Homebrew 8-bit retro computing