What Is REX
REX is completely plug and play flash memory upgrade. REX plugs into the Option ROM slot, with no soldering or necessity to open the laptop case.
Rex provides support for up to 8 in-circuit selectable option roms. That means, you can have 8 different software packages on one Option ROM, and select between them without physically unplugging anything.
In addition, REX is in-circuit, software reprogrammable. That means you can change, patch, or replace replace an Option ROM image without any special hardware or physically unplugging REX.
REX comes pre-programmed with release 1 REX Manager software. REX Manager allows you to pick which of the 8 ROM images is the one currently in use.
REX Manager operates "behind the scenes" to make sure the currently selected Option ROM image is automatically enabled on every power cycle. This is an impressive trick since REX does not receive power while the laptop is off (unlike the RAM memory circuit).
Also, REX Manager is able to do this while using a minimal amount of RAM space (about 10 bytes)!
Advanced BASIC ROM Replacement Mode (OPTIONAL)
For users that with the do-it-yourself spirit, an optional feature of REX can be enabled.
With a single wire soldered in place, REX permits BASIC ROM replacement!
This means that you can disable the built-in BASIC/TEXT/TELCOM ROM on your motherboard and replace it with a specific block of REX flash memory. Typically, this will be the same BASIC/TEXT/TELCOM ROM image we know and love, with a few changes. So, you can upgrade your Model T with little tweaks like Y2K, the lomem patch, new character sets, put your name on the main menu, etc.
Installing REX Manager - It's Easy
From a cold restart, simply typing
will install the REX system.
To start REX Manager, press reset and hold the ESC key. Then from basic type:
REX Manager will start, allowing you to manage which ROMs stored in REX can be used, and when.
A separately loadable utility allows you to burn ROM images into REX.
Future releases of REX will have a built in file system for managing REX files, TPDD files and RAM files.
There will be approximately 512K of file storage.
A likely future feature is a facility for freezing/thawing RAM images to/from flash. This would offer an easy way to quickly backup all RAM to flash, or switch between multiple configurations of applications and files in RAM.