This is Something-fishy-with-the-Color-Slab in view mode; [Up]
Date: Sun 18-Nov-1990 07:38:08 From: whelan@huey.uhcc.Hawaii.Edu (The Obscure Guru) Subject: Something fishy with the Color Slab Has anyone noticed something funny with the specs for the NeXTStation Color? My copy of the progaganda says that the machine has 1.5 Megabytes of VRAM for the display. However, this does not appear to be enough considering the following specs on the display itself: 16 bits per pixel 1120 pixel horizontal res 832 pixel vertical res Thus, 2(bytes) * 1120 * 832 = 1820 Kbytes ~= 1.777 Mbytes Is system ram used for the display as well? Or perhaps only the color bits are kept in VRAM... Thus, 1.5(bytes) * 1120 * 832 = 1365 Kbytes ~= 1.333 Mbytes This seems an odd way to do things, but I can't think of any other even semi-reasonable explanation (other than I've forgotten how to multiply). :^) Does anyone have suggestions, perhaps based on more than just idle speculations like mine?
Date: Sun 20-Nov-1990 21:40:25 From: aozer@next.com (Ali Ozer) Subject: Re: Something fishy with the Color Slab In article <10326@uhccux.uhcc.Hawaii.Edu> The Obscure Guru writes: > Has anyone noticed something funny with the specs for the >NeXTStation Color? My copy of the progaganda says that the machine >has 1.5 Megabytes of VRAM for the display. However, this does not appear >to be enough considering the following specs on the display itself: > 16 bits per pixel > 1120 pixel horizontal res > 832 pixel vertical res >Thus, 2(bytes) * 1120 * 832 = 1820 Kbytes ~= 1.777 Mbytes The VRAM used for the screen does not need to store the alpha. The backing stores of windows *are* 16 bits. However, when a window is displayed on the screen, there's no need to show the alpha bits; transparency is used when you composite between windows, and then you end up using the backing stores. The same holds for the 2-bit display and the NextDimension; the screen VRAM doesn't keep alpha. BTW, the screen VRAM is separate from the memory in the machine, so you have that 1.5M in addition to the 12M in the NextStation Color. Ali
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