>>The calc is: >> >>( (horizontal pixels) x (vertical pixels) x (bits per pixel aka bit >> depth) ) / 8 = memory required to display at that bit depth, in bytes. >> Divide again by 1024 for KB. >> >>So: >>( 640 x 480 x 16 ) / 8 = 614400 bytes (which is 600K). >> >>Therefore, 512K isn't quite enough, sorry to say. >> >>( 640 x 480 x 8) / 8 = 307200 (300K), so you can get 256 colors (8 >> bits). >> >>The bit depth is of course the number of bits (or power of two) >> required to get that range of colors in a pixel -- therefore 8 bits = >> 2^8 = 256 colors. >> >>Ivan. > > Damn. Thats too bad. I was hoping 512K would be enough so I could try > and swap out the 65220 video chip with the video chip from a > PB1400 (65225). > > Now if I could only figure a way to increasew the VRAM on a duo..... > > Mad Dog
Actually, the MacOS uses 15-bit video for "thousands of colors" mode.. this is why we've never really gotten any great 2D accelerators, since That Other OS only supports 16-bit... Even so, the calculations come out at 560kB.. still too much. Depending on the host chip, you'd be better off taking the VRAM and gfx chip out of the 1400, rather than mixing the ram on the Duo's board with the 65225... I don't know if the chips are identical in size... never looked. If you manage to get this to work, though.. I'd love to hear! I'm all for wierd HW mods!! (let's put a color TFT and color gfx chip in a Newton 2100!! Oops.. wrong list :p ) -Andy ---------- Duo/2400 List, The friendliest place on the Net! A listserv for users and fans of Mac subportables. FAQ at <http://www.themacintoshguy.com/lists/DuoListFAQ.shtml> Be sure to visit Mac2400! <http://www.sineware.com/mac2400> To unsubscribe, E-mail to: <[EMAIL PROTECTED]> To switch to the DIGEST mode, E-mail to <[EMAIL PROTECTED]> Need help from a real person? Try. <[EMAIL PROTECTED]> ---------- Dr. Bott | 10/100 Ethernet for your 2400 is finally here! MPC-100 | <http://www.drbott.com/prod/mpc100.html> RoadTools $30 PodiumPad available at Apple retail stores, $20 Traveler CoolPad at Staples. Both in white for iBooks at <http://roadtools.com> Midwest Mac Parts ][ <http://www.midwestmac.com> After-market parts for Macs. ][ 888-356-1104 ][ MacResQ Specials: LaCie SCSI CDR From $99! PowerBook 3400/200 Only $879! Norton AntiVirus 6 Only $19! We Stock PARTS! <http://www.macresq.com>
