1000EX Possible Alternate Monitor?

[jfriordan]

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!

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!

 

[ross.dykes]

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.

 

[Torch]

How's it all working out? Any upgrades planned?

 

[ross.dykes]

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!

 

[indyjoenz]

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

 

[ross.dykes]

Very cool! Kind of makes me want to keep looking for something like an IBM 5153. =)

 

[shirsch]

Just finished setting up an MCE2VGA with my newly acquired Tandy 1000EX. Display is stable and clear but it's too tall to fit on my bench monitor which, naturally, has no height or width adjustments available (only positioning). Is anyone aware of alternate firmware for this device that shrinks vertical size?

 

[Plasma]

Just finished setting up an MCE2VGA with my newly acquired Tandy 1000EX. Display is stable and clear but it's too tall to fit on my bench monitor which, naturally, has no height or width adjustments available (only positioning). Is anyone aware of alternate firmware for this device that shrinks vertical size?

There are many different versions here. The CGA output resolution was changed a few times.

I have instructions for updating the firmware here but some of the links are dead due to age.

 

[shirsch]

Thanks, but it doesn't look like any of those specifically changed the display size. Still, I ordered a USB Blaster on eBay (Waveshare brand) and will see if I can get anywhere.

 

[vwestlife]

Tandy 1000s use 225-line text mode, to make the text more readable adding a gap line between each row so that the bottoms of descenders don't touch the tops of descenders. This may cause the image to go off the edge of the screen on some TVs and monitors, so if you're using an official Tandy version of MS-DOS, you can type MODE 200 to switch it into 200-line mode (or MODE 225 to go back to 225-line mode).

Also there's MODE TV which will set it to 200-line mode, switch to 40-column text, and enable the composite color burst. Pressing F2 during POST does the same thing.

Post in thread 'Tandy Text Modes'

May 13, 2008

I've never touched those. All I can tell you is that I own a Tandy 1000, 1000HD, and TL/2 and they all use 8x8.

I have an original Tandy 1000 (with BIOS ROM version 01.00.00) and it uses 225-scan-line text mode by default. If you hit F12 during the startup memory check, it will boot up in 40-column, 200-scan-line text mode with the composite color burst enabled. Otherwise, you get 80-column, 225-scan-line text mode with the color burst disabled. You can also enter "MODE TV" (or "MODE 200") in Tandy DOS to switch to 200-scan-line text mode. "MODE 225" reverts back to...

• vwestlife

 

[Plasma]

Thanks, but it doesn't look like any of those specifically changed the display size. Still, I ordered a USB Blaster on eBay (Waveshare brand) and will see if I can get anywhere.

The switch to 480 line output added support for Tandy's 225 line mode. With only 400 line output it will be cut off. So you can either switch the Tandy to 200 line or change the firmware on the MCE2VGA.

 

[Eudimorphodon]

Tandy 1000s use 225-line text mode, to make the text more readable adding a gap line between each row so that the bottoms of descenders don't touch the tops of descenders. This may cause the image to go off the edge of the screen on some TVs and monitors, so if you're using an official Tandy version of MS-DOS, you can type MODE 200 to switch it into 200-line mode (or MODE 225 to go back to 225-line mode).

FWIW, this actually caused issues with some real CGA monitors, with the top or bottom being a little cut off with the default vertical height/position. (And not all monitors had knobs to adjust those.) It might also somewhat problematic with some other scalers (the default bad firmware in the GBS8220 boards would cut it off a bit), but yeah, it's critical on the MCE2VGA because the default mode just *exactly* fits the 400 horizontal lines of plain VGA.

 

[SeaHawk8802]

You can also use a more modern computer monitor like a Dell 2005FPW. I had a Dell 2005 FPW back in high school and college, and this is how I know that they have a composite video jack on them. However, you'll need to look for one with a sound bar to just make you aware.

You can also entertain the idea of getting a reasonably priced modern DVI or HDMI-driven monitor. I currently use a Gigabyte M32Q monitor that can be driven with either DisplayPort or HDMI. You'd most likely have a better chance of using a retro tin or internal video up-scaler . The RGB to HDMI is maybe a suitable alternative to up-convert the digital TTL signal from your Tandy 1000EX.

 

[Torch]

You'd most likely have a better chance of using a retro tin or internal video up-scaler . The RGB to HDMI is maybe a suitable alternative to up-convert the digital TTL signal from your Tandy 1000EX.

1000EX composite output will look terrible no matter what you use for a monitor.

What is a retro tin or an internal video up-scaler in regards to a CGA based computer? Google ain't helping me out on those terms.

 

[Istarian]

1000EX composite output will look terrible no matter what you use for a monitor.

What is a retro tin or an internal video up-scaler in regards to a CGA based computer? Google ain't helping me out on those terms.

I suspect he is referring to a retroTINK branded product, maybe whatever the original one was?

 

[vwestlife]

1000EX composite output will look terrible no matter what you use for a monitor.

If you're willing to sacrifice color, composite will look fine if you disable the color burst (MODE BW80) and run it through either the luma (Y) pin of an S-Video input or the green Y jack of a component video input.