the old 68k based macintoshes dont really have a video card, they just have some wierd IC that has a frame buffer that draws to the screen. if you take a closer look at that second simm in your quadra or whatever, you will notice it only has 68 pins instead of 72. those are the VRAM memory modules for the video buffer, and usually come in sizes of either 256kb or 512kb. also most of the time there is an additional 256k or 512k soldered onto the motherboard. so you either have 512k, 768k or 1024k of video memory.
the reason duke 3d was so slow on 68k macs is because the video card handed all of the drawing routines to the cpu (same with floppy drives and other devices on the system) which slowed things to a standstill. if you get something like a performa 600CD and slap in a nubus video card, even with it being 68030, its alot better than a 68040 with the onboard video card.
Post by oompa loompa on Jan 18, 2006 18:50:45 GMT -5
oh, i see =P i don't really know a lot about mac's, except for the really really old mac plus that had a 68000. everything was done by the cpu, even the floppy interface, since the interface was adopted from the apple ][ design. the video frame buffer was generated by a couple programmable logic chips (these chips didn't even have any internal registers, everything was logic equations!)
apple was dumB when it came to managing the system bus. making the cpu handle everything from the video buffer to the floppy drive was a stupid idea, as most graphics intense applications suffered (even up into the G3 era)
although there was a mac in the macintosh II family that had dual dedicated 6502 CPU's for the floppy drives, and even wierder, 64 pin ram! but at least it had a good processor (40 MHz 68030)
just about the only thing that didnt seem to kill the systems speed was the 5 MB/s SCSI controller.
if you ever come across a power macintosh thats faster than 180 MHz (powermac or Performa 6400/180 or Powermac 6500/250, 275 or 300) it will run duke3d good (if you dont put MacOS 9.x on it, stick with 8.1 or 8.5) you can also put in a Voodoo2 or Voodoo3, because the onboard ATI Rage blows chunks.
Post by oompa loompa on Feb 13, 2006 0:46:09 GMT -5
the design of making the cpu do everything is suppose to make the computer cheaper, so that not as many sophisticated components are used. the design didn't make the computer any cheaper anyhow, their computers were already expensive x.x
now i hear that they're now gearing towards using an intel cpu in their machines. lotsa hardcore apple fans are pissed =P, haha
yea, im suprised they didn't just go to that new PPC cell CPU, it's architecure looks like it could really compete in the PC market (although it would be a pain in the ass to program)
but i would be pissed if i bought one of the dual PPC G5's and blow about 10k then apple turn around and starts developing on x86-64 which would make everything incompatible.
but i do like their ad on their website:
"whats an intel processor doing in a mac? alot more than it ever did in a PC"
but the PPC users get the last laugh, with the quad core configuration in the new G5's (dual P4's with dual cores) they eat so much power and generate so much heat that they actually have to be water cooled...
The G5's are water cooled to minimize noise. The G5 isn't anywhere near as hot as the Prescott P4s, or the dual core Pentiums. Those have been known to melt motherboards. ;D Have you seen the HSF in one of those PCs? They look like a friggin airplane engine!
It's not a wonder that Intel is now trying to work from the Pentium M core. Anything else uses too much power. The Yonah chip Apple is using looks pretty nice. It's not the fastest chip out, but it gets good scores with pretty decent power usage. It's only 32bit though. the x86_64 extensions won't be added to that line of chips until the end of the year.
recently i've added replaced the 68000 cpu clock selector circuit on my monster sega genesis and now added two more clocks in addition to the stock clock and 13.4 mhz dot clock: 12 mhz, 8.9489 mhz, and 16 clocks. this means that i can now play overclocked games on the sega genesis at 12 and 8.9 mhz without the vdp getting messing up.
now, everyone knows i have like every sega genesis game ever made, like 600 total (only counting the good games =P). so, would it be useful to the community, for me to start making a chart or guide on which sega genesis games overclock the best, and which games perform better on overclocked machines?
That would be a great idea, actually. But can you beat my record of 25.6 MHz? Once I fix my pulse generator I'll be shooting for 30.
oh, i see =P i don't really know a lot about mac's, except for the really really old mac plus that had a 68000.
I got the idea to overclock my MD after overclocking the 68030 in my Macintosh IIsi. Those were the days ... sheesh, it's only been maybe 6 years. Where DOES the time go.
Last Edit: May 18, 2007 4:36:11 GMT -5 by Epicenter