The OEL TTX2000 Issue 2.3 ROM
The OEL Issue 2.3 ROM is an earlier version of the firmware.
It uses the same teletext acquisition code, but a different telesoftware downloader.
Code and data from this ROM remains in the Issue 1.2 ROMs but is unreachable and unused. Some of the unused code in the newer ROM differs slightly, suggesting that it was based off a version other than 2.3.
The 4Data telesoftware adaptor ROM Issue 1.2
The 4Data Issue 1.2 ROM is identical to the Volex ROM apart from the data defining the menu screen.