REX: Difference between revisions

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[[Image:Red_logo_small.png||center]]<br/>
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== What Is REX ==
<big> '''REX Products for Model T laptops! '''</big>


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 16
<table border="0">
in-circuit selectable option roms. That means, you can have 16 different
<tr><td>[[Image:REXCPM.PNG]]       </td><td>    All of REX + CP/M support!    ---></td><td>[[REXCPM]]    </td><td>[[Image:rexcpm.jpg]]</td></tr>
software packages on one Option ROM, and select between them without
<tr><td></td><td></td><td></td></tr>
physically unplugging anything.
<tr><td>[[Image:REXsharp.PNG]]      </td><td>    Next Gen Flash based REX     ---></td><td>[[REXsharp|REX#]] </td><td>[[Image:rexsharp.jpg]]</td></tr>
 
<tr><td></td><td></td><td></td></tr>
In addition, REX is in-circuit, software
</table>
reprogrammable. That means you can change, patch, or replace an Option ROM image
without any special hardware or physically unplugging REX.
 
An additional feature is a facility for freezing/thawing up to 16 RAM images to/from flash. This offers an easy way to quickly backup all RAM to flash, or switch between multiple snapshots of RAM. This is similar to the "fast switch environments" on Remem: it would be like having multiple laptops in the same case!
 
For advanced users, 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.
 
[[Media:Rex_OverviewV4.2.pdf|REX Overview PDF]]
 
== REX Manager ==
 
REX comes pre-programmed with REX Manager software. REX
Manager allows you to pick which of the ROM or OS images is the one
currently in use, and also supports management of RAM images.
 
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).
 
REX Manager is started by running the program REXMGR.BA from Menu.
 
== Advanced BASIC ROM Replacement Mode (OPTIONAL) ==
 
For users 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, power cycle the laptop and the simply type
<code><pre>CALL 63012</pre></code>
 
will install the REX system.
 
You should see a program in the Menu called REXMGR.BA.  Running this program will always start the REX Manager software.
 
== Additional Utilities ==
 
REXUPG.CO is a utility that allows the user to upgrade the internal REX Manager software.
 
REXMR.CO is a utility that allows the user to program upgraded main rom images into REX for use in "ROM Replacement" installations.
 
== Future Roadmap ==
 
REX2 will be available in the near future.  It provides additional blocks of SRAM, allowing an all RAM mode of operation, for CP/M support.
 
 
== Rel. 4.3 Beta testing: bug reports/fixes ==
 
I should not have sent out the "4.3 beta" a few weeks ago as it was too alpha.
 
I found a number of bugs that were subtle and affected stability.  Now that those are resolved, and the TPDD routines are robust to TPDD problems, I now have a candidate final load.  All the features I have considered have been implemented.
 
R4.3b supports M100/T102 only right now.  I will have a T200 R4.3b shortly.
 
== Rel. 4.2 Beta testing: bug reports/fixes ==
 
1)  DONE R4.3 - found error in code - Year bug - the year data is not correctly preserved by REX when RAM images are saved and loaded.  Solution - implement a mechanism that maintains the year data properly.
 
2)  directory bug with entry for block 31 - it appears that the name entry for block 31 is not displayed correctly, investigation continuing.
 
3)  DONE R4.3 - sound is disabled - sounds - currently REX uses audible clicks to indicate progress, which can be annoying. Solution - disable audio, replace with some other mechanism.
 
4)  DONE R4.3 - directories are now sorted in descending order of date/time - directory order - current directory entries are displayed in order of block number, which is problematic since this causes reordering whenever REX garbage collection forces an image to be moved from one block to another. 
 
5)  Overall stability - there may be some bugs lurking still regarding ram image swapping and stability.  Still under investigation.


6)  Robustness for TPDD routines - under investigation


7) DONE R4.3 - included choice for refresh or revert - Restore from current ram image - there is no easy way to restore from the current backup image.  Solution TBD. work around is to copy the backup image to a new block, and then install that image.
<big> '''How to order --->[[Ordering Information]] '''</big>


8)  DONE R4.3 - non-blank block recovery - it is possible that REX attempts to copy an image to a non blank block.  This situation is indicitive of a problem with the system since this should never happen.  If it does occur, the system gets in a deadlock condition.  Solution - make sure REX has no bugs in this functionality first, but an option to "name" or "delete" the offending block would be a nice safety system.


9) DONE R4.3 - enter function displayed on line 2 - state function of <enter> for cursor item on screen somewhere - don't leave it to memory only
{| class="wikitable"
|'''Type'''||'''Supported Models'''||'''Memory type'''||'''Memory permanent?'''||'''CP/M?'''||'''Option ROMs?'''||'''RAM backups?'''||'''PCB2MOLEX Carrier?'''||'''Robustness improvements?'''
|-
|REXCPM||M100, T102||Static RAM, 2MB or 4MB||NO - SRAM||YES||YES||YES||YES||YES
|-
|REXsharp||M100, T102, T200, NEC||Flash, 1MB||YES- FLASH||NO||YES||YES||YES||YES
|-
|}


10) DONE R4.3 - <TAB> is included in top line now - indicate <tab> is used to toggle groups.
  Memory permanenance:  After using REXCPM, if you were to remove it from the laptop, it would eventually discharge
  and the memory contents would degrade. So, you have the extra work of backing up REXCPM if you want to remove it,
  with a subsequent restore when you want to use it again.
  REX#, being flash based, does not have this issue.


11) DONE R4.3 - order is now RAM ROM OS (SYS) (SYS is a superuser feature) - change group display order to avoid tabbing past OS type.


== Enhancement Requests ==


<table border="1">
No longer orderable (from me), and end-of-support:
<tr><td>Status</td><td>Description</td><td>Requester / Date</td></tr>
<table border="0">
<tr><td>Unknown</td><td>Support import of file from frozen RAM image to the thawed RAM image. RAM images can be used in a way similar to subdirectories. Therefore it is useful to be able to retrieve files from frozen RAM images</td><td>[[User:Jhoger|Jhoger]] 08:16, 16 April 2009 (PDT)</td></tr>
<tr><td>[[Image:REXclassic.PNG]]   </td><td>   Classic Flash based REX      ---></td><td>[[REXclassic]]</td></tr>
<tr><td>Done R4.3</td><td>Suggestion: make the TAB order OptROM, RAM image, Main ROM since Main ROM switch will be significantly less used. (order is now RAM ROM OS SYS)</td><td>[[User:Jhoger|Jhoger]] 19:54, 18 April 2009 (PDT)</td></tr>
<tr><td>Unknown</td><td>Add a visual progress indicator for flash functions.</td><td>[[User:Sadolph|Sadolph]] 04:36, 19 April 2009 (PDT)</td></tr>
</table>
</table>


nb: to put a username+datestamp just type 4 tildes <nowiki>~~~~</nowiki>


[[Category:Model T Hardware]]
[[Category:Model T Hardware]]

Latest revision as of 06:28, 1 April 2022

Red logo small.png


REX Products for Model T laptops!


REXCPM.PNG All of REX + CP/M support! --->REXCPM Rexcpm.jpg
REXsharp.PNG Next Gen Flash based REX --->REX# Rexsharp.jpg


How to order --->Ordering Information


Type Supported Models Memory type Memory permanent? CP/M? Option ROMs? RAM backups? PCB2MOLEX Carrier? Robustness improvements?
REXCPM M100, T102 Static RAM, 2MB or 4MB NO - SRAM YES YES YES YES YES
REXsharp M100, T102, T200, NEC Flash, 1MB YES- FLASH NO YES YES YES YES
  Memory permanenance:  After using REXCPM, if you were to remove it from the laptop, it would eventually discharge 
  and the memory contents would degrade.  So, you have the extra work of backing up REXCPM if you want to remove it,
  with a subsequent restore when you want to use it again.
  REX#, being flash based, does not have this issue.


No longer orderable (from me), and end-of-support:

REXclassic.PNG Classic Flash based REX --->REXclassic