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The Amiga, Circa 2010 — Dead and Loving It
Orion Blastar writes "While many Amiga users have moved on to Linux, Mac OS X, and even, gasp shock, Microsoft Windows, some of us don't want to give up so easily. There are two open source projects that are keeping the Amiga legacy alive even if Amiga Inc. seems to be deader than a doornail and not really doing much but selling old Classic Amiga games for new platforms. Like WINE, there was a project to run AmigaOS 3.1 software for Linux and other platforms, but it evolved instead into an open source operating system named Amiga Research OS, or AROS. AROS is best run inside an emulator, and while it is not a modern OS like Linux, it can be downloaded and run inside of Linux (and the downloads section has more). While it is not ready for prime time yet, it is a promising OS that is being ported to many platforms and uses the user friendly Amiga GUI we Amiga users grew up with." Read on for more.
"OK — maybe AROS is not modern enough for you, and you like Linux instead. Then you might like Anubis OS, as it is a hybrid of AROS and Linux. Much like when Apple took NextStep (based on *BSD Unix and the MACH kernel) and the classic Mac OS to make Mac OS X, this project wants to take Linux and AROS and do the same thing.
For those who want the classic Amiga, there is UAE, the Universal Amiga Emulator, which needs kickstart ROMs and boot disk images to work. You can buy them from Amiga Forever; the emulator comes with all the files you need plus other goodies.
For the classic Amiga 68K series, it is recreated via the Minimig, which uses SD cards instead of floppy disks; a must for retro computer hobbyists. AmigaOS 4.1 exists for PowerPC based SAM 440EP systems like the SAM 440Ep systems and parts sold here. (I am not associated with Amiga Kit or Amiga Inc. or any Amiga company. I am just an Amiga user since 1985 and very much into retro computing.)"
For those who want the classic Amiga, there is UAE, the Universal Amiga Emulator, which needs kickstart ROMs and boot disk images to work. You can buy them from Amiga Forever; the emulator comes with all the files you need plus other goodies.
For the classic Amiga 68K series, it is recreated via the Minimig, which uses SD cards instead of floppy disks; a must for retro computer hobbyists. AmigaOS 4.1 exists for PowerPC based SAM 440EP systems like the SAM 440Ep systems and parts sold here. (I am not associated with Amiga Kit or Amiga Inc. or any Amiga company. I am just an Amiga user since 1985 and very much into retro computing.)"
It sounds like you are talking about auto-stretch scaling. That the monitor is at 800x600, the game is 320x240 and is automatically up-scaled to 800x600 by the OS.
There were only two basic horizontal resolutions on a standard Amiga - 320 and 640. There was hardware to switch resolutions (and palettes and bit depths) on a scan line by scan line basis. There were no aliasing problems because there was no real scaling done, the graphic chip just output pixels at one of two different rates (albeit with different palettes and bit depths), potentially on a line by line basis.
So you could grab the menu bar at the top of the screen and pull it down (vertically) to reveal another screen behind it. Separate frame buffers - one program (games and paint programs especially) could write all over the frame buffer of a screen that was invisible or only partially visible on the screen. All this vertical screen motion didn't involve moving any bits around in memory, so it was instantaneous - no waiting for anything to redraw.
The Amiga allowed you to dedicate back buffers (so called "smart refresh") to ordinary windows as well, to avoid redraws when a part of a window was exposed or brought to the front. Screen level double buffering, hardware line drawing, pixel blitting, bitmap movement, vertical palette changes, hardware sprites, all par for the course.
With a hardware sprite, for example, you could have a mouse pointer that moved around without ever touching the underlying frame buffer. The application didn't care, didn't worry, the mouse pointer was just an operating system controlled sprite that was overlaid on the video output in hardware. None of this "hide the mouse pointer", then draw, then restore (or XOR) the mouse pointer stuff that was common in competing operating systems at the time.
Similar hardware, by the way, was used to implement many of the early Atari game machines, inexpensive consoles that often implemented very nice games with only 4K of RAM (albeit typically 16 or more kilobytes of game cartridge ROM on top of that). On Atari game consoles there was usually no bitmap at all, just a bunch of hardware tiles and sprites. Can't fit much of a bitmap in 4K of RAM (or less in some cases).
In any case, the Atari graphics hardware guy ended up at Amiga, and the remaining Atari folks designed an Amiga competitor (the Atari ST) with very conventional frame buffer support and none of the exotic graphics hardware goodness Atari had a considerable reputation for, let alone as implemented on steroids in the Amiga hardware design, at very low cost.