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1000EX Possible Alternate Monitor?

ross.dykes said:
I also have a Tandy 1000EX and needed a monitor, so I decided to come up with a somewhat period correct and far worse alternative than using an RGB2HDMI converter =). I picked up an arcade monitor (LCD in this case, so not quite period correct) that supports 15kHz, and then built a small circuit to convert the digital RGB signal to something the arcade display would be happy with.

View attachment 1249586View attachment 1249587

It is conceptually similar to some of the other RGB to analog methods floating around out there, I've attached a schematic in case anyone wants to have a look. It's just 2 n-channel FET's to adjust dark yellow down to brown, 6 Schottky diodes and 8 resistors. I used 2k pots to adjust the 5v TTL signals down to 1v (the schematic doesn't show this correctly due to laziness), and to adjust the pull-down for the intensity signal. The other resistors were somewhere in the 10-30 ohm range.

As I understand it the correct way to produce brown is to watch for the RGBI bit pattern to be 1100, and to attenuate the green signal accordingly to get the color you want. I couldn't work out a way to do this without components requiring external power, so I cheated and cobbled together an OR gate with FETs driven by the blue and intensity signals. The FETs steal power for the drain from the red and green signals via diodes and a resistor, and are not being used properly as the source is connected to the "load" (green pull-down) and a resistor to ground. This effectively pulls down green unless blue or intensity are on, so it also affects low-intensity green. I actually like the way this looks as it's less washed out, so it turned out to be a "feature". It's not perfect as green is always going to be pulled down a little bit, but it looks OK when playing Kings Quest!
Click to expand...
Oh wow! Very cool. Have to be honest you all are allot better at that stuff than I am. I did end up buying a CM-5 on eBay, good condition and works. Thanks for the reply my friend!
 
Ooh, CM-5, nice! Did the monitor arrive in one piece? I tried that once and it arrived in many pieces, so I've been gun shy about it since.
 
Not really related to the alternate monitor discussion, but I decided to dust off the EX and play with it a bit, poor thing has been sitting idle for a while.

Picked up a RGB to HDMI hat for the rPi so I can get this connected to my office flat panel TV (not enough space for everything to have its own display sadly), a new 3-in-adapter for the EX that has 2 serial ports: https://github.com/rkrenicki/Tandy-EX-HX-3in1-V2

and a serial wifi module: https://www.tindie.com/products/theoldnet/rs232-serial-wifi-modem-for-vintage-computers-v4/. Time to get this thing on the Internet!
 
Someday I'll fix my CM-11.... which is disassembled on my workbench.

But, for my 1000RL, I use an "Ezpix 85 Covid" converter, which converts CGA, EGA and VGA to 15khz analog RGB. I have that going out to a 15khz RGB CRT: an AppleColor RGB that originally shipped with the Apple IIGS.

Right now the Ezpix 85 can be found on Ebay for around $30.

I love the way it looks. Here are some action shots:
Bean ansi art
LORD
Lemmings
dos text
desktop action
 
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