Possible Sacrilege

[KeithB]

But fun:
https://spectrum.ieee.org/upcycle-a-vintage-lcd

(An article about re-using a Tandy100 with original LCD with a modern microcontroller

[Maximilian Hohmann]

Hello!

(10-26-2022 06:49 PM)KeithB Wrote:  ... But fun: ...

I guess we associate a different meaning to the word "fun" ;-)

I could understand if someone puts a modern display into an old computer to make it more readable and nicer to look at in general. But a modern computer paired with an old low-contrast display with a very limited viewing angle and overall unpleasant in every respect. Why, just why?

Regards
Max

[Jeff_Birt]

(10-26-2022 06:59 PM)Maximilian Hohmann Wrote:  I could understand if someone puts a modern display into an old computer to make it more readable and nicer to look at in general. But a modern computer paired with an old low-contrast display with a very limited viewing angle and overall unpleasant in every respect. Why, just why?

Regards
Max

The M100 LCD is pretty good, much better than most at the time. It is not a modern 1.21Giga pixel, 27 quadrillion colors though. The keyboard on them is really nice. A very nice feel, many people still like using them for writing to this day.

[mfleming]

As long as the original motherboard is preserved and returnable, I see nothing wrong with this. Consider the 41CL and Classic CPU replacement boards. ACT replacement chip would count too.

Now if only they had an emulator (Z80?) that could run the original ROM image!

[KeithB]

(10-26-2022 07:51 PM)Jeff_Birt Wrote:  The M100 LCD is pretty good, much better than most at the time. It is not a modern 1.21Giga pixel, 27 quadrillion colors though. The keyboard on them is really nice. A very nice feel, many people still like using them for writing to this day.

And the multiple LCD controllers to improve speed sound intriguing.

[Jeff_Birt]

(10-27-2022 12:35 PM)KeithB Wrote:  And the multiple LCD controllers to improve speed sound intriguing.

Not to increase speed, just to have enough drivers and RAM for every pixel. The screen updates are still sent a byte at a time across the bus from the microprocessor.

[Garth Wilson]

(10-27-2022 03:34 PM)Jeff_Birt Wrote:  

(10-27-2022 12:35 PM)KeithB Wrote:  And the multiple LCD controllers to improve speed sound intriguing.

Not to increase speed, just to have enough drivers and RAM for every pixel. The screen updates are still sent a byte at a time across the bus from the microprocessor.

It's my understanding that having each controller handle only a small portion of the display improves the duty cycle on the various rows and columns, improving the contrast. I've never had a 40x8, but I've had 40x2's with excellent contrast, and 40x4's which are handled like two 40x2's in the same LCD module, again with excellent contrast.

I always kind of liked the packaging of the TRS-80 model 100. Packaging is a huge part of the design project of making a product like that, and is undoubtedly a large part of the reason that at least until recent years, a laptop cost twice as much as a desktop with the same capabilities. Anyone who has ever tried to make a compact unit like this in hobby, with lots of I/O connectors accessible around the outside, and not wasting any space, knows it's a challenge that can be very frustrating and cause a lot of false starts and starting over. Been there, done that.

[Jeff_Birt]

(10-27-2022 07:32 PM)Garth Wilson Wrote:  It's my understanding that having each controller handle only a small portion of the display improves the duty cycle on the various rows and columns, improving the contrast. I've never had a 40x8, but I've had 40x2's with excellent contrast, and 40x4's which are handled like two 40x2's in the same LCD module, again with excellent contrast.

Each row/column driver can only drive so many pixels, i.e. each one only has so much 'screen buffer' RAM inside. There is nothing more to it than that.

[Garth Wilson]

(10-27-2022 07:36 PM)Jeff_Birt Wrote:  

(10-27-2022 07:32 PM)Garth Wilson Wrote:  It's my understanding that having each controller handle only a small portion of the display improves the duty cycle on the various rows and columns, improving the contrast. I've never had a 40x8, but I've had 40x2's with excellent contrast, and 40x4's which are handled like two 40x2's in the same LCD module, again with excellent contrast.

Each row/column driver can only drive so many pixels, i.e. each one only has so much 'screen buffer' RAM inside. There is nothing more to it than that.

What I meant is that there's an added benefit, even if that's not why it was done that way.

[Ren]

The article mentions "tossing out" the original motherboard.
THAT (to me) is sacrilege!
(Find another enthusiast who would get that motherboard a loving home.

[BobVA]

The display controller on the M100/102 also included a hardware scroll function that, weirdly, wasn't enabled. (This is particularly evident in the TELCOM app.)

Steve Adolph did some very interesting experimentation with this, culminating in a hardware scroll ROM patch for the 100 / 102.

He posted a nice write up and the patch here.