Difference between revisions of "REXsharp"

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'''under development! stay tuned!'''
= Overview =
= Overview =

Revision as of 10:22, 28 November 2020



What is REX#?

REX# is an add-on memory card that plugs into the Option ROM socket in a supported laptop, augmenting significantly the amount of memory in the laptop as well as what that memory can be used for.

  • REX# provides 1MB of flash memory for the laptop.
  • REX# puts bank switched flash memory into the OPTION ROM memory bank (1x32k bank)
  • The 1MB flash (32 blocks of 32kB) may then be accessed, one 32k block at a time.
  • REXMGR (aka REX Manager) software, loaded into the first 32k block, makes all this memory useful!

Main Features and Functions of REX#

REX# (via REXMGR software) enables several key capabilities for the Model T user.

  • Option ROMs: Applications for Model T laptops were originally distributed as Option ROMs. These ROM images may be loaded into flash blocks, and then quickly switched/activated for use by REX Manager.
  • RAM Images: Users can quickly backup or restore the current working RAM of the laptop into one of the 32k flash blocks. This provides a great way to store data, programs, or quickly recover from a cold boot situation.
  • Quick Menu: the laptop main menu now has some custom keystrokes that speed up REX# usage.
  • Active Optrom display: the main menu also shows the name of the installed option ROM.
  • Additional nice things: REX Manager fixes the Y2K date display problem

Model T variants supported by REX#

  • TRS-80 Model 100
  • Tandy 102
  • Tandy 200
  • NEC PC-8201, 8201A, 8300
  • Olivetti M10
  • KC-85 (well I don't have one but I'm sure it would work!)


Model 100:

  • In Europe and UK, and probably elsewhere, there are newer versions of M100 that have different boards.
  • Model numbers are 26-3801B and 26-3802B.
  • REX# does not function correctly in these models, due to the significantly different main ROM.

Olivetti M10 note:

  • In order to use REX#, the Olivetti M10 must have it's main ROM updated to be "like the M100".
  • The M10 is compatible with standard 27C256 eproms, so it is a matter of obtaining the replacement main ROM image, burning the image and mounting the chip in the main ROM socket.
  • the link to the M10 ROM page --> Olivetti M10 ROM patch


REX Products home page

REX Products ordering information


  * REX# is now generally available, and can be ordered subject to availability.
  * Inventory status will be kept up to date at the Ordering page.

Quick Start

So, you have just received your REX# and want to get going.

1) Power down the laptop. Follow the hardware installation steps.

2) Power on your laptop, enter BASIC, and type



T200 (Bank 1 only):


NEC (Bank 1 only):


REX Manager will check for and install the REXMGR menu entry, and REX Manager will start. REX# ships with TS-DOS pre-loaded, so you can get started with that application immediately.

In the main Menu of the laptop, you will see a program called REXMGR is now installed. You can run that program any time to enter REX Manager, to load and run all the different ROMs you wish, and to allow you to manage your RAM backups.

To load files to/from REX, you MUST have a way of hosting files REX can access over the serial (RS232) port.

To host files for transfer to REX via REX Manager alternatives include

as the best TPDD devices for use with REX Manager.

Hardware Installation

Installation information for Model 100 here ----> REX# M100 install

Installation information for Tandy 102 here ----> REX# T102 install

Installation information for Tandy 200 here ----> REX# T200 install

Installation information for NEC here ----> REX# NEC install

Installation information for M10 here ----> REX# M10 install


REX Manager User Guide for REXsharp

Technical Information

Use with MVT100 external Video

Currently the REX Manbager software is not compatible with the VT100 driver for M100. I am working on integrating this function, but for now they conflict because they both try to use the CHGET hook.

It is possible to use use MVT100 with REXCPM by un-installing the REX hook (CNTL-X at MENU). After REX is inoperative, the VT100 driver can be loaded. But since there is no way to remove the VT100 software once installed, I would suggest caution.

As soon as I have integrated the VT100 driver into REXCPM, I will post an update.



As shipped, REX# contains the currently supported REX Manager ROM image. It also includes TS-DOS. Upgrades to REX Manager ROM will be provided over time to address bugs or possibly add features.

this will be updated when there is an upgrade available

Upgrade Utility for REX#

A tool is available for upgrading REX# to a newer build.

this will be updated when there is an upgrade available

Option ROM Images for Download

Validated OPTROM Images for M100/T102

Validated OPTROM Images for T200

Validated OPTROM Images for NEC


I would like to thank those that have contributed to the project:

John Hogerhuis - for all his technical support, and for this Wiki resource

Kenneth Pettit - for VirtualT as this project would not have happened without it

Brian White - for his innovative PCB2MOLEX carrier design