meulenbr@cstw01.UUCP (Frans Meulenbroeks) (11/22/88)
Hi! I think I have a better proposal for doing graphics under Minix on the ST (perhaps the idea can be used for PC's as well). Writing directly to /dev/mem is not that nice. What if we add a new device /dev/screen or something like that. What this device should do: upon open malloc a chunk of 32000 bytes on a 256? byte boundary to store the screen. This area can be written to using the write call (just like for /dev/mem). A close will release the memory. And now the main difference with Gerry's proposal: add an ioctl call which will allow you to make the device the current screen by tickling the hardware. Of course this ioctl call returns (or perhaps stores) the previous value, since there is another ioctl call which will restore things. This has a major advantage: the text screen is left intact when doing graphics, and one can build a picture offscreen and display it at once. Another possibility is to add minor numbers to this device. This means that you can have several off screen painting areas, even allowing for some kind of animation. Later on people can add graphic primitives for instance to draw a line, a circle or to bitblt an area. (by the way: is there anyone who has already (68k assembly?)code for such primitives? I'd like to hear from you). Perhaps I'll try soon myself. Any suggestions, advice, help & discussion welcome! -- Frans Meulenbroeks (meulenbr@cst.prl.philips.nl) Centre for Software Technology ( or try: ...!mcvax!philmds!prle!cst!meulenbr)