Hacker News Reader

Comment by jwells89 | Hacker News Reader

Classic Mac OS all the way up through OS 9 handles 1-bit and grayscale displays quite well.

I’ve thought for some time now that if one were build a System 7.5/Mac OS 8 laptop with an e-ink or high quality transflective display (like that found on the Playdate[0]) and new 68k/PPC SoC built on a modern node with a modern battery, the resulting device would be surprisingly useful even if lacked connectivity. It’d sip power, with battery life likely measured in weeks or months and could probably be kept charged with a lid-sized solar panel.

[0]: https://play.date/

View on HN

> It’d sip power

Are you sure? I think Classic MacOS effectively always busy-looped (WaitNextEvent would block, but only if the OS could run another event loop), never sleeping its (single) CPU.

https://developer.apple.com/library/archive/documentation/ma...:

“The Event Manager reports a null event when your application requests an event and your application’s event stream does not contain any of the requested event types”

If that’s true, that modern node CPU would not sleep most of the time, but just loop a lot faster.

Would a 68k on a modern node running at a fraction of its potential max speed burn through very much power? Apple managed to get multiple hours of battery life out of 68k chips on classic MacOS PowerBooks...

Note that that function has a sleep parameter. It doesn't return until an event has arrived or the sleep time has elapsed.

I may be mistaken, but I don’t think Apple ever stopped the CPU (a 68000 could be stopped and continue running on an interrupt, but I don’t think they ever used that)

Yeah, it might not have saved power, but it did allow the machine to spend time on useful things.

So the CPU on a PowerBook never went into a low power state? The maximum power draw of a 68020 apparently was 1.75W, so I guess it's possible.

Does the 68020 even have low power states? I couldn’t find a definitive answer, but did find https://www.manualslib.com/download/1342088/Motorola-Mc68020... and https://www.nxp.com/docs/en/data-sheet/MC68020UM.pdf, which dont’t seem to mention them.

Would it be any different than, say, battery-powered portables like the TRS-80 Model 100?

As described at the time, the contemporary Sinclair Z88 had a separate bit of management logic that kept the Z80 CPU asleep until there was some interaction, in order to get ludicrous runtimes on 4xAA. (I wouldn't be surprised if the Model 100 did similarly, but there was no point in doing it on machines that plugged into the wall...)

You could do this to an emulated 68k Mac as well, software written after the PowerBooks shipped should all be ok with being held in sleep most of the time. A few things would need hacks like cursor blink (don't do it) and updating displays like clocks (wake every minute?). Interesting.

I have 9.2.2 on an old imac with an SSD on it, it’s lovely.

Reply on news.ycombinator.com