REX Classic module

The Classic version of the ubiquitous REX module for the M100 family of computers.
Manufacturer: StarDust


Note: Thanks to 48KRAM for donating the FLASH chips for these. This allowed us to keep the price low.

Original design by Steven Adolph, this PCB version by Brian K. White

The REX name is a concatination of a few previous projects by its creator, Steven Adolph. ReMem, a flash memopry device + EXZTRAM OPTION ROM (RAM) memory card. REX is a plug and play flash memory upgrade for TRS-80 Model 100, Tandy 102, Tandy 200*. REX plugs into the Option ROM socket, with no soldering or modifications required and no necessity to open the laptop case.

This 'REX Classic' is a PCB revision by Brian K. White which was made to plug into a slick PCB carrier of his design and bring out the signals needed for programming. The REX Classic is no longer being made or supported, but is a well known, stable device that is a 'must have', IMHO, for the M100 family owner. There are two newer versions the REX# and REXCPM the links to these are in the Links tab that offer more and different features.

Primary features: (From Steve's site linked below)

  • REX allows for storage and quick, easy switching between OPTION ROM images. Once the binary software images are loaded into REX, the user can easily jump back and forth between different applications.
  • REX provides the ability to backup and swap working RAM images. At the press of a key, your current RAM contents are saved in REX. Furthermore, you can reload any saved RAM image for use. This creates a library of RAM images, which has a number of uses. This offers an easy way to quickly backup all RAM to flash, or switch between multiple snapshots of RAM. It is like having multiple laptops in the same case!
  • REX includes an interface to TPDD devices (like TPDD, NADSbox, LaddieCon, Backpack etc) for loading and saving binary images to external storage.
  • R_EX modifies they way MENU displays the date, effectively fiing the Y2K 'bug'.
    In addition, REX is in-circuit, software reprogrammable. That means you can change, patch, or replace an Option ROM image without any special hardware or physically unplugging REX.
For advanced users, REX provides some additional features:
  • REX distinguishes between traditional OPTION ROM software, and alternative OS software which runs from the option rom memory location. This allows for some interesting future capabilities like CP/M or a FORTH based system.
  • REX also supports "Main ROM Replacement". This means that, with the addition of a single wire, the main rom on the laptop may be replaced by a version stored in REX. This allows for flash-upgradeable main ROM images, to support patches, custom Menu and character sets, LOMEM patch, Y2K patch etc. Facility is included to support dual Main ROM images, and the ability to switch between them.

*Compatible with: TRS-80 Model 100, Tandy 102. It 'will' work with the Model 200 but requires reprogramming and the hardware to do the programming. Our suggestion is not to buy one for a M200 unless you can do this programming yourself.



Links to both Steve and Brian's websites

Main REX webpage (Steve):
REX Classic main page (Steve):
PCB Files for Brian's design:
Brian's build page:


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