Building a REX

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20190730 232012.jpg

Introduction

Building a REX
Note this isn't the original REX. This is essentially a REX1 with a modified pcb layout from Steven Adolph's original.
It is electrically identical, and uses the same software and firmware.
The PCB layout and shape are modified to snap into a 3d-printed carrier, and provide connections for power and PORT_EN to facilitate programming the CPLD.

Original version of this page, for building the original REX1

Parts & Materials

Other Compatible Flash Chips and how to identify them

Tools

DLC9G Clone.jpg
Cheap Chinese clone is fine.
Look at the pictures for ones that say model DLC9G, or DLC9LP. Don't put "DLC9G" or "DLC9LP" in the search, you will only get the overpriced ones.
Get one that includes a "flying leads" cable, with separate loose individual wires on one end.
Usb-ttl-cable.jpg
A cheap usb-ttl cable is perfect. It's cheap, and already ends in loose wires with female dupont pins.
Just use the red and black wires and ignore the rest.
  • PC with at least one usb port, and a COM port or usb-serial adapter.
  • Sandpaper, medium grit (120 or so), and a hard flat surface like a cutting board.
Do not necessarily need anything fancy. I actually used this exact one to build a few REXs, although now I use a Hakko FX-888D.
Or the strongest reading glasses you can get at a local drug store. 3.00x or higher.
1x6 1x4 shunt.jpg
0.1" (2.54mm) pitch single row male pin header
1x6
1x4
one shunt


  • A Tandy Model 100, 102, or 200.


Software

  • Xilinx ISE 14.7 Lab Tools
Lab Tools is a subset of ISE. You can use either ISE or Lab Tools, but you only need Lab Tools to program the REX.
This software is old and needs special futzing to make it work, no matter what OS you are using.
Installing on Ubuntu Linux
Installing on Windows.
  • A DOS (aka TPDD client) for the M100
There are several dos's, and several ways to get one installed. These are a few options:
Get dlplus and use the "teeny" installer that comes with it to install Teeny.
Get mComm for Windows or Android and use the dos installer that comes with it to install either Teeny or TS-DOS.
Use the TS-DOS MP3 and play it from a phone into the cassette port to install TS-DOS. (SOUND OFF:CLEAR 0,57089:RUNM "CAS:DOS100.CO")
Get a real tpdd and bootstrap it's utility disk to install "Floppy".
The rex firmware updater needs a TPDD server.
dlplus and mComm above are both tpdd servers, which come with tpdd client installers, and previously you used to be able to just use one of those packages for everything.
But there is a bug in the latest REX build 254 files, such that it only works (reliably) with LaddieAlpha as the TPDD server.
But LaddieAlpha does not come with any dos installer.
So, right now it's a bit inconvenient. You have to get one of the above packages just to use it's dos installer, and then you have to get LaddieAlpha also, and use it for the rest of the rex setup process.
Start there, and follow the links to whatever is the latest "REX Release x.x Rebuild Package" zip file.

Procedure

Prep the Bare PCB

Lay a piece of medium grit (100-200) sandpaper face up on a hard flat surface like a cutting board.

Sand the edges of the PCB on the sandpaper just enough to clean off the panelization break-away points.

Castellation flags.jpg

Use magnification to look closely at the castellated edge contacts for copper or gold "flags" hanging on the edge of most contacts. Scrape them off with an xacto knife.

Solder the Electronic Components

Soldered top.jpg
Soldered bottom.jpg

Solder these parts onto the matching labeled locations on the pcb.

U1 = XCR3064XL
U2 = 29F800
U3 = LP2980-3.3
R1 = 10K
C1 = 1uF
TP1 & TP2 = right-angle pin (optional)

Don't be too intimidated by the tiny legs on that TSOP-48 chip.
Just use magnifying glasses, lots of flux, and the DRAG TECHNIQUE.
Another example: https://youtu.be/09qb0KY_IF4

The TP1 and TP2 pins are only needed if you think you will ever perform the hardware modification required to use the main rom management feature.

Clean the Finished PCB

Even "No-Clean" flux should still be removed as much as possible after soldering.

The best is to use an ultrasonic cleaner and Branson EC fluid.

If you don't have that, then at least use 99% isopropyl alcohol and a small paint brush. This will still leave flux trapped under the chips no matter how much you soak it or wash it, but if it's no-clean flux it should be ok to leave it.

Program the CPLD

Now we need to flash the CPLD (Xilinx) with the .jed file. This configures the blank CPLD into a functional circuit that actually does something.

  • Get the .jed file from here.
  • Connect the jtag, 5vdc, and PORT_EN jumper.

Snap the PCB Into the Carrier

Place the end of the PCB without the hole into the carrier first, then snap the rest of it in.

Flash the Firmware

Follow the 4.9 update directions to load the firmware.

The directions for the 4.9 update state that you use any tpdd device to serve the 3 files to the M100/T102/T200, but in fact at least at present, it does not work with actual tpdd1 or tpdd2 drives at all, and is not reliable with just any tpdd server either. You must use specifically LaddieAlpha.

Directions for a Linux PC:

Outline

  • Get a proper serial cable
  • Install Teeny the M100/T102/T200.
  • Get LaddieAlpha onto a PC.
  • Get the 3 update files.
  • Run LaddieAlpha in the dir with the 3 update files.
  • Use Teeny to copy rf149.co to the M100.
  • Run rf149.co on the M100.

Details

Back up any files off of M100. M100 will be wiped.

Cold reset M100 (ctrl+pause+reset)

Power off M100

Install REX into M100

Connect serial cable between M100 and PC

Power on M100

On PC, open a terminal.

$ mkdir ~/trs-80
$ cd ~/trs-80
$ wget http://bitchin100.com/files/linux/dlplus.zip
$ unzip dlplus.zip
$ cd dlplus
$ ./teeny-linux /dev/ttyUSB0

Follow prompts both on PC and on M100 closely.

On M100:

BASIC
RUN "COM:98N1ENN"

On PC:

Enter
wait...

On M100:

Enter
?HIMEM:CALL9643
see that Top: says 62213 (Or whatever it says for you. 32k machine should say 62213)
CLEAR 0,62213
NEW
MENU

On PC:

Enter
should be back at a shell prompt now
$ cd ~/trs-80
$ mkdir LaddieAlpha
$ cd LaddieAlpha
$ sudo apt install mono-complete
$ wget http://bitchin100.com/files/linux/LaddieAlpha.EXE
$ wget http://bitchin100.com/wiki/images/4/4f/R49_M100T102_254_rebuild.zip
$ wget http://bitchin100.com/wiki/images/6/63/M100_OPTION_ROMS.zip
$ unzip R49_M100T102_254_rebuild.zip
$ unzip M100_OPTION_ROMS.zip
$ mono ./LaddieAlpha.EXE /dev/ttyUSB0 6

On M100:

should be at menu
TEENY.CO
> L RF149.CO
> Q
should be at menu
BASIC
CLEAR 0,55000
MENU
should be at menu
RF149.CO
Answer Y
Wait...
should be at menu
ctrl+pause+reset
should be at menu, ram wiped
BASIC
CALL 63012
should be at menu, REXMGR should appear in menu

REX is now ready to use, and empty except for TS-DOS.
Now install a rom. Ex: Ultimate Rom II

REXMGR
press TAB once
screen should say "TS-DOS* ------"
press right-arrow once, highlight should move to "------"
press F2
Loading from image filename: UR2100
Hit any key when TPDD ready.
Loading 0:UR2100.BX     ####
now it should say "TS-DOS* UR2100 ------"

UR2 is now loaded into REX, but not currently active, TS-DOS is.

right-arrow to highlight UR2100
press enter
Y

UR2 is now active, and the equivalent of "CALL 63013,1" to "install" an option rom was already done for you by REX or REXMGR.

F8 back to menu.

Leave LaddieAlpha running on PC while you load more roms.

Ctrl+C to exit LadieAlpha.

Done!

That was the last step. You're done! Consult the REX docs to start using it!

References

Current PCB source is maintained on github

Version c6 pcb This version of the pcb is obsolete, but has pics of the firmware flashing procedures.

Version c8 pcb This version is also now obsolete, but the only difference is the pcb dimensions and matching carrier.

User Manual

Original sources and support files

Copies of some of the sources and support files, and new sources for some things modified from the originals