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REX is an on-board virtual option rom library and ram backup device invented and designed by Steven Adolph.
REX is an on-board virtual option rom library and ram backup device designed by Steven Adolph.


[http://bitchin100.com/wiki/index.php?title=REX REX Documentation]
There are a few different types of REX now: [http://bitchin100.com/wiki/index.php?title=REXclassic REX Classic], [http://bitchin100.com/wiki/index.php?title=REXsharp REX#], and [http://bitchin100.com/wiki/index.php?title=REXCPM REXCPM].
 
REX# and REX Classic provide mostly the same functionality.
 
* On-board, software controlled, multiple option rom library. Option roms are loaded from a PC over serial cable, and activated/selected/deleted all from software.<br>
* On-board multiple full ram image backup & restore. You can snapshot your entire system and restore it later. This can serve as both a recovery after a hard reset or crash or total battery drain, or can be used merely for more storage like ram expansion banks, where you keep more apps & data in multiple ram images than the computer can hold by itself, and switch between them.
 
The differences are:
 
:REX# is newer and currently sold and supported by the creator. The firmware and software are newer and receiving more updates.
 
:REX Classic provides one feature that REX# does not, which is the [http://bitchin100.com/wiki/index.php?title=Main_ROM_Management_Feature Main ROM Management Feature]. It allows you to boot from a main rom image on the REX instead of the internal main rom, and manage & modify the main rom image purly from software once the hardware install is done one time. See also [[FlexROM_100]] which adds more hook-up convenience and a 3rd fall-back boot option still without re-opening the case even if you bork both main rom images in the REX.


[[Building a REX|Build your own REX]]
REXCPM is a very different beast. The headline feature of REXCPM is CP/M. It provides a way to run CP/M on the 100.<br>


[https://drive.google.com/open?id=0Bys6eLbSbYyhU01uYjFYNnpkTmM A few more ROMs]
:It also provides all of the REX# functions, at least outwardly. But the basic REX/REX# functionality isn't really the same because it is a purely volatile RAM device. When it loses power, it loses it's virtual "firmware", rom images, and ram backup images.
:These are mostly the same as the roms zip file from the REX docs.
* Disk+2.0 is from a commercial rom I found in one of my machines. It hasn't been uploaded anywhere else yet that I know of.
* MFORTH is a newer version than in the zip file.
* AZ23 and AZ24 are AlphaZ 2.3 and 2.4
* HOOT2C is from an EME Systems "OWL" (Online Weather Logger) machine.


Some roms in the roms zip from the REX docs have been patched to work better with REX, so generally you want to use these copies specifically rather than other copies of the same roms.
:You can still use a REXCPM to recover from a hard reset, as long as the computers memory battery hasn't died and as long as the REXCPM hasn't been removed from the computer for more than a few minutes. But if the computer sits on the shelf for more than a few weeks or if you remove the REXCPM from the machine for more than a few minutes, you will need a PC and serial connection and go through the entire setup process again.


==REX Hacking==
:The contrast is, the old REX and new REX# are flash devices which never die. They are actually useful for storing rom images and ram backup images, and you can restore from them with nothing else needed even after the computer has fully died. For instance you don't have to bootstrap over serial to get TS-DOS installed, you have it in rom the same as if you had an original TS-DOS option rom.
Work in progress. Current version c8


This is a version of REX1 that I have modified to address a few things with the original REX1:
:There is a [https://github.com/bkw777/REXCPM_UPS battery backup for REXCPM], but Steve didn't make it and doesn't sell them. You have to buy the parts and build it yourself. But it adds a battery to the REXCPM and allows the REXCPM to be removed from the computer and still retain it's data for at least a few years.
* Let the pcb manufacturer pre-castellate the pcb edge contacts, so the pcb comes from the manufacturer almost ready to use, needing only a little light sanding to clean up the panelization break-off points.
* Provide a practical and safe way to supply 5vdc to the board during CPLD programming.
* Provide a practical and safe way to hold PORT_EN high during CPLD programming.
* Fit into a 3d-printed carrier that fits the option rom socket.
* Cosmetic clean up: remove un-used component footprints, arrange remaning components into a symmetrical arrangement, remove the 0-ohm resistor, silk screen text.


* PCB: https://oshpark.com/shared_projects/DKF7eN1c
[http://bitchin100.com/wiki/index.php?title=REX REX Documentation]
* Sled: https://www.thingiverse.com/thing:3723135
<gallery>
rex-bkw-c8-1.png
rex-bkw-c8-2.png
rex-bkw-c8-3.png
rex-bkw-c8-4.png
</gallery>


[https://photos.app.goo.gl/aNfjvB1XucSehPGB9 Version c6 is tested and verified.]<br>
[[Building a REX|Build your own REX Classic]]
The electronics have not changed between c6 and c8.


The c6 photos show the new 5v and PORT_EN connections for the initial CPLD programming.
[[ModelT_roms|roms]]

Latest revision as of 22:52, 4 January 2024

REX is an on-board virtual option rom library and ram backup device designed by Steven Adolph.

There are a few different types of REX now: REX Classic, REX#, and REXCPM.

REX# and REX Classic provide mostly the same functionality.

  • On-board, software controlled, multiple option rom library. Option roms are loaded from a PC over serial cable, and activated/selected/deleted all from software.
  • On-board multiple full ram image backup & restore. You can snapshot your entire system and restore it later. This can serve as both a recovery after a hard reset or crash or total battery drain, or can be used merely for more storage like ram expansion banks, where you keep more apps & data in multiple ram images than the computer can hold by itself, and switch between them.

The differences are:

REX# is newer and currently sold and supported by the creator. The firmware and software are newer and receiving more updates.
REX Classic provides one feature that REX# does not, which is the Main ROM Management Feature. It allows you to boot from a main rom image on the REX instead of the internal main rom, and manage & modify the main rom image purly from software once the hardware install is done one time. See also FlexROM_100 which adds more hook-up convenience and a 3rd fall-back boot option still without re-opening the case even if you bork both main rom images in the REX.

REXCPM is a very different beast. The headline feature of REXCPM is CP/M. It provides a way to run CP/M on the 100.

It also provides all of the REX# functions, at least outwardly. But the basic REX/REX# functionality isn't really the same because it is a purely volatile RAM device. When it loses power, it loses it's virtual "firmware", rom images, and ram backup images.
You can still use a REXCPM to recover from a hard reset, as long as the computers memory battery hasn't died and as long as the REXCPM hasn't been removed from the computer for more than a few minutes. But if the computer sits on the shelf for more than a few weeks or if you remove the REXCPM from the machine for more than a few minutes, you will need a PC and serial connection and go through the entire setup process again.
The contrast is, the old REX and new REX# are flash devices which never die. They are actually useful for storing rom images and ram backup images, and you can restore from them with nothing else needed even after the computer has fully died. For instance you don't have to bootstrap over serial to get TS-DOS installed, you have it in rom the same as if you had an original TS-DOS option rom.
There is a battery backup for REXCPM, but Steve didn't make it and doesn't sell them. You have to buy the parts and build it yourself. But it adds a battery to the REXCPM and allows the REXCPM to be removed from the computer and still retain it's data for at least a few years.

REX Documentation

Build your own REX Classic

roms