You could use the U1MB Rom Builder
or The ROM Generator to manipulate the OS (or BASIC or GAMES)
ROMs within the U1MB Flash memory and flash the resulting ROM file to the flash chip. However at least one version of the chip used in Lotharek's U1MB units is not supported by the flasher (which is in fact the currrent SDX flasher for U1MB but happens to flash the whole flash chip if a 512K ROM file is given as input)
. We just found about that problem chip recently. (Please see this thread for details)
I've recently updated the flasher in ROM builder to the latest but, even the latest apparently still does not support SST39SF040 (It has 4K sector size instead of 64 as it is in other chips)
, it recognizes the chip but if you proceed with the flash it will brick your U1MB. if your chip is not SST39SF040
then you are OK, but I would still suggest checking the datasheet for your brand of chip before flashing to make sure it has 64K sector size.
Trub apparently will update the flasher some time soon to add support for 4K sector size.
Edited by atari8warez, Mon Mar 18, 2013 12:30 AM.