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Why the original Macintosh had a screen resolution of 512×324

512pixels.net

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Re: Why the original Macintosh had a screen resolution of 512×324

#121

Post by rasz »

p_l wrote: post #109
hulitu wrote: post #99

Earlier quoted context omitted.

And marketing said, when LCDs were pushing CRT out of the market, that you don't need to send the whole image to change a pixel on an LCD, you can change only that pixel.

except DVI is essentially VGA without Digital-to-Analog part, and original HDMI is DVI with encryption, some predefined "must have" timings, and extra data stuffed into empty spaces of blasting a signal designed for CRT. I think partial refresh capability only came with some optional extensions to DisplayPort.

Im not even sure if partial refresh is a thing outside of e-Paper displays. The best we can do on DP is Variable Refresh going all the way down to Panel Self-Refresh.

Re: Why the original Macintosh had a screen resolution of 512×324

#122

Post by rasz »

perching_aix wrote: post #32
bluGill wrote: post #28

Earlier quoted context omitted.

Have you ever seen something running at 30 Hz? Or even 15? The difference in flicker between 30 and 60 is much much larger than the difference between 60 and 120! Yeah 60 isn't flicker free, any finite number is not (there is probably quantum limits), but realistically you reach a point where you can't really tell. For most purposes 60Hz is close enough, though you can still tell.

I don't remember frankly. For what it's worth, TV sets would always be 50 Hz here (PAL) (unless they did some tomfoolery I'm not aware of and ran at 100 Hz "in secret" or something) and evidently I could watch those on end without too many holdups for years and years, so clearly it wasn't a dealbreaker. But on monitors, yeah, I just wouldn't tolerate it, whereas 85 Hz felt perfect (no discernible flicker for me that…

> TV sets would always be 50 Hz here (PAL)

but only half the screen at a time so in effect every other line was flickering at 25Hz

Re: Why the original Macintosh had a screen resolution of 512×324

#123

Post by rasz »

badc0ffee wrote: post #97

It doesn't say exactly why 512x342 was chosen. But I'm more interested in why it was changed to 512x384 on later Macs. Is it just to fill the full 4:3 screen? Beyond that, this article really wants to tell you how amazing that resolution was in 1984. Never mind that you could get an IBM XT clone with "budget" 720x348 monochrome Hercules graphics that year and earlier.

Both MDA and Hercules were 50 Hz. Real mid eighties king of cheap crisp displays would be 12 inch 640x400@71Hz Atari SM124 monitor. You could buy Atari ST + SM124 + Atari SLM804 laser printer + Calamus DTP package for the price of just the Apple laser printer alone :)

Re: Why the original Macintosh had a screen resolution of 512×324

#124

Post by monkeyelite »

account42 wrote: post #117
monkeyelite wrote: post #83

Earlier quoted context omitted.

4k jumped the gun. It’s just too many pixels and too many cycles. And unfortunately was introduced when pixel shaders starting doing more work. Consequently almost nothing actually renders at 4k. It’s all upscaling - or even worse your display is wired to double up on inputs. Once we can comfortably get 60 FPS, 1080p, 4x msaa, no upscaling, then let’s revisit this 4k idea.

WTF are you talking about, 60 FPS for 4K isn't even that challenging for reasonably optimized applications. Just requires something better than a bargain bin GPU. And 120+ FPS is already the new standard for displays.

I’m telling you that even if those are the numbers on paper, the software and hardware are using tricks to achieve it which lower the overall quality.

So yes you get 4k pixels lit up on your display, but is it actually a better image?

And yes there may be high end hardware which can handle it, but the sw still made design choices for everyone else.

There are also image algorithms which are not as amenable to GPUs which are now impossible to compute effectively.

Re: Why the original Macintosh had a screen resolution of 512×324

#125

Post by badc0ffee »

rasz wrote: post #123
badc0ffee wrote: post #97

It doesn't say exactly why 512x342 was chosen. But I'm more interested in why it was changed to 512x384 on later Macs. Is it just to fill the full 4:3 screen? Beyond that, this article really wants to tell you how amazing that resolution was in 1984. Never mind that you could get an IBM XT clone with "budget" 720x348 monochrome Hercules graphics that year and earlier.

Both MDA and Hercules were 50 Hz. Real mid eighties king of cheap crisp displays would be 12 inch 640x400@71Hz Atari SM124 monitor. You could buy Atari ST + SM124 + Atari SLM804 laser printer + Calamus DTP package for the price of just the Apple laser printer alone :)

I had a XT clone + Hercules at the time (and SIMCGA for games), and the 50Hz refresh wasn't as bad as you'd think - the MDA CRTs were designed with slow decay phosphors to reduce flicker.

I actually had no idea that Atari made a laser printer. Everyone I knew with a ST (admittedly, not many people) was either doing MIDI or playing video games.

Re: Why the original Macintosh had a screen resolution of 512×324

#126

Post by badc0ffee »

fredoralive wrote: post #104
badc0ffee wrote: post #97

It doesn't say exactly why 512x342 was chosen. But I'm more interested in why it was changed to 512x384 on later Macs. Is it just to fill the full 4:3 screen? Beyond that, this article really wants to tell you how amazing that resolution was in 1984. Never mind that you could get an IBM XT clone with "budget" 720x348 monochrome Hercules graphics that year and earlier.

The 512x384 models are Macintosh LC adjacent, so the original LC monitor (the LC itself can do 640x480), or the Colour Classics. AFAIK it was partly in order to making the LC work better with the Apple IIe card (although the IIe software uses a 560x384 mode). A Hercules card, whilst nice does suffer from the same non-square pixels issue as the Lisa, so not as nice for creating a GUI.

> although the IIe software uses a 560x384 mode

Nice, that's line doubled from the //e's 560x192 and would probably look crisp.

Re: Why the original Macintosh had a screen resolution of 512×324

#127

Post by kwertyoowiyop »

kragen wrote: post #82
nothercastle wrote: post #63

Earlier quoted context omitted.

Why did they need 60hz? Why not 50 like Europe? Is there some massive advantage to syncing with the ac frequency of the local power grid?

Conventional wisdom a few years after the Macintosh was that 50Hz was annoyingly flickery. Obviously this depends on your phosphors. Maybe it was already conventional wisdom at the time? I feel like the extra 16% of screen real estate would have been worth it.

A white background at 50hz was pretty flickery, at least to my NTSC-experienced eyes, on a TV. Maybe they could have used longer persistence phosphors in their monitor, but then motion and animation would blur.

Re: Why the original Macintosh had a screen resolution of 512×324

#128

Post by justinrubek »

monkeyelite wrote: post #83
stefan_ wrote: post #45

Earlier quoted context omitted.

Displays are still bandwidth killers today, we kept scaling them up with everything else. Today you might have a 4k 30bpp 144hz display and just keeping that fed takes 33Gbit/s purely for scanout, not even composing it.

4k jumped the gun. It’s just too many pixels and too many cycles. And unfortunately was introduced when pixel shaders starting doing more work. Consequently almost nothing actually renders at 4k. It’s all upscaling - or even worse your display is wired to double up on inputs. Once we can comfortably get 60 FPS, 1080p, 4x msaa, no upscaling, then let’s revisit this 4k idea.

Make it 120fps and I could agree.

Re: Why the original Macintosh had a screen resolution of 512×324

#129

Post by jecel »

jdswain wrote: post #93
silvestrov wrote: post #21

Earlier quoted context omitted.

No, this is very wrong. The 68000 is 32 bit internally and it has 32 bit registers: https://en.wikipedia.org/wiki/Motorola_68000 Externally it had 16 bits for databus and 24 bits for addresses. That is why we later got the 32 bit clean ROMs as Apple used the upper unused 8 address bits for flags.

It has 32-bit registers, but it has a 16-bit ALU, so it's a matter of opinion if that makes it a 16 or 32-bit processor. I'd go with 32-bit in that it's instruction set gives the impression to the programmer that they are working with a 32-bit system. And for more evidence, the Z80 is referred to as an 8-bit processor but has a 4-bit ALU.

The 68000 actually had three 16 bit ALUs, so could munch a peak of 48 bits per clock cycle. Only one could do all operations while the other two were basically just add. These days we would say there were part of the AGU (address generator unit) but one of them was shared with the data register operations.

Re: Why the original Macintosh had a screen resolution of 512×324

#130

Post by jhallenworld »

CRTs are very forgiving- 512x342 vs x384 would have made very little difference. You could still get square pixels by minor adjustments to vertical and horizontal size.

My question is what is the htotal and vtotal times in pixels and lines? Maybe there was a hardware savings to have vtotal exactly equal to 384 (which is 128 times 3). Perhaps they saved one bit in a counter, which may have resulted in one fewer TTL chip.

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