[criddell]

Maybe you can answer this then.

Back in the early 80’s, Radio Shack made the TRS-80 Model 100 laptop. It ran for 20+ hours on 4 AA batteries.

A few years later, Psion came out with a series of small devices that ran on 2 AA batteries and got 30+ hours of runtime.

With modern electronics and displays, could something like a model 100 be made that could run for hundreds or even thousands of hours on 4 AA batteries?

[iancmceachern]

As others have noted, its the "modern display" that does it.

From the wiki here:

"Display: 8 lines, 40 characters LCD, twisted nematic (gray) monochrome, with 240 by 64 pixel addressable graphics. The screen is reflective, not backlit.[3] The screen was made by Sharp Electronics.[4] The LCD controllers are by Hitachi: (10) HD44102CH column controller ICs and (2) HD44103CH row driver ICs; the HD44102CH's provide the programmable hardware interface to software. The refresh rate is about 70 Hz (coarsely regulated by an RC oscillator, not a crystal)."

It's not even backlit.

[criddell]

Surely a display of similar specs made today would draw a fraction of the power the similar panel from 1983 did, no?

[iancmceachern]

Not really. Fundamentally things like this are driven by physics, not engineering or cleverness.

We've had solar powered calculators with LCD displays for decades. We're not really going to get much lower power without changing Fundamental technologies at the material and physics level. Much of what we have material and physics wise "is what it is", on this planet anyway.

[reaperducer]

With modern electronics and displays, could something like a model 100 be made that could run for hundreds or even thousands of hours on 4 AA batteries?

The biggest problem is the screen. People aren't going to tolerate a 40x8 (320px x 64px) screen with no backlight and limited contrast.

Putting a modern screen on it is going to eat power beyond your budget.

The M100's refresh rate wasn't great, so replacing the LCD with an e-ink display would be comparable, except it would far more expensive.

[mananaysiempre]

> With modern electronics and displays

Wouldn’t the second part work against the first? There’s a lot of pixels you need to push to refresh a good modern display. I guess you could use a bad (as in low-res) modern display, but I wouldn’t expect those to be particularly concerned with energy efficiency either, just cheap.

[criddell]

A low-res display would be fine. In fact the same display as the original Model 100 would be great.

A sibling mentioned e-ink and that might be ideal. With a fast enough CPU and race-to-sleep scheduling, the machine would mostly be in a low power idle mode.

I think the temptation for a lot of designers here would be to use Linux and I think that would be a big mistake. A custom, basic OS with a few simple programs like the Model 100 or Psion 5 had would be ideal, at least for me. Or maybe even something like FreeRTOS (like the Flipper uses) if it is low power enough.

[reaperducer]

A low-res display would be fine. In fact the same display as the original Model 100 would be great.

Use one for a while before you decide.

I still use mine every couple of weeks for distraction-free writing, and to read the news. The display updates VERY slowly. So slowly that you don't have to be a very strong typist to get way ahead of it.

[criddell]

The display worked better 40 years ago. They lose contrast and responsiveness with age.

My favorite calculator is an HP-28s and it too has become slow and hard to see.

[ac29]

Yeah, the above referenced TRS-80 Model 100 had a 240x64 monochrome display with no backlight. No surprise it didnt use much power.

[raddan]

I would kill for an e-ink version. For a palmtop I don’t think a high-res color display is necessary.