Macintosh SE resolution?

cbmeeks

Hello all! Been a while since I've been around.

I've been messing around with a few Macintosh SE's lately (the B/W ones) and I started wondering if the Propeller could emulate the same graphics mode.

The SE uses a resolution of 512x342x1 with a contiguous layout (giant frame buffer). That would be 175,104 bits = 21,888 bytes = 21.375KB.

In terms of the Propeller, would the math break down as such?: 512 bits wide = 512/32 bits = 16 longs * 342 lines = 5,472 longs.

Way too big for a single COG but that seems doable in hub RAM.

I imagine I would need a few COGs for the mouse pointer, drawing boxes, text, etc.

So, would you think all of this is well within the Propeller's abilities?

Thanks!

pedward

Yep, there is already the 1bpp mode in the prop video hardware. This is no different than 2 color VGA on the prop. You could start with any of the 640x480 demos and modify it from there.

ericball

While the Prop can do 1bpp easily, the oddball resolution is going to present some challenges for modern monitors. Easiest would be to generate 640x480 with wide borders followed by 1024x768 using double wide pixels and line doubling + letterboxing. Both will show some vertical squeeze due to different pixel aspect ratio. This could be avoided by tripling every fourth line for the 1024x748 display.

Of course, if you are using the Macintosh 9" display then that's a whole different story. The original 128K Mac used LSI logic to generate the display, which the Propeller should be able to emulate. You'd need to reuse the high voltage section of the monitor, and you'd need a 'scope to see what the original low voltage hardware is generating.

However, while you could fit the bitmap into HUB RAM, that doesn't leave much space for actual programs.

Ale

There is a ready to use 512x384 driver, of course you can modify it to only display only 342 lines of data and the rest as blank, if your plan is to use a normal VGA monitor.
I read somewhere that the vertical refresh of the original Mac monitors where not 60 Hz but something close like 58 (I don't remember the exact number) , they didn't seem to like any other frequency, at all...

cbmeeks

Thanks for the info!

@Ale

I don't know the exact frequency, but the monitors were "60-ish" Hz. All the docs say 60 but that's probably because it was easier to round up.

But, interesting fact, the monitor's refresh rate wasn't tied to the AC mains frequency like most other monitors and TV's. This was to all the Macs to work unaltered in either Europe or North America and with no need for PAL/NTSC versions.