128a-3aj@e260-3b.berkeley.edu (Jonathan Dubman) (10/01/88)
So the Mac IIx has a 68030 and a 68882 running at the same speed as the original Mac II. BIG DEAL. I don't understand what Apple is doing here. All the PC manufacturers are coming out with 20 and 25 MhZ processors with 30 MHz on the near horizon. And Apple comes out with a 16 MHz machine. So it has a built-in PMMU which future versions of the Mac OS will make use of, and UNIX can use, and it has all sorts of little optimizations, but really, why all the fuss over what seems like a very minor upgrade? So it has the 1.4-meg drive. IBM had that a year and a half ago with the PS/2, and they have a reputation for using only time-tested technology, whereas Apple is viewed as the technology leader in microcomputers. Maybe leader in user-interface, but it seems like they are still behind in the hardware department. After a point, for most operations, I'll agree that the speed of the computer is not that important. However, the Mac II is not yet at that point. -Jonathan Dubman
usenet@cps3xx.UUCP (Usenet file owner) (10/01/88)
In article <14873@agate.berkeley.edu>, Jonathan Dubman (128a-3aj@e260-3b.berkeley.edu) writes: >So the Mac IIx has a 68030 and a 68882 running at the same speed as the >original Mac II. > >BIG DEAL. I agree I'd like to see a BIG improvement in the Macintosh line, but I can see what may be some of the reasons for not making a big jump yet. >I don't understand what Apple is doing here. All the PC manufacturers are >coming out with 20 and 25 MhZ processors with 30 MHz on the near horizon. >And Apple comes out with a 16 MHz machine. Beware of comparing MHz. Admittedly, this topic has been beaten to death on various newsgroups, but processors vary a lot in what they get done each clock cycle. When you get up to 68020/68030-class machines, the caching and prefetch start really making a difference in terms of instructions-per-cycle. Built in virtual memory is also a real help, at least when you have a VM-based operating system--but it slows down the processor a little bit. A 68020 (arguably) does more work each cycle than an 80286. Also, something else to watch is the memory access time. With high-speed memory prices going up, putting a 30-MHz 68030 in your machine will cost a LOT--not just the processor and main memory, but putting a reasonable cache (say, 32-64K) of really high-speed memory in to avoid wait states (disclaimer: I haven't seen a 68030 hardware manual, so I don't know its memory rate/cycle time ratio). >So it has a built-in PMMU which >future versions of the Mac OS will make use of, and UNIX can use, and it has >all sorts of little optimizations, but really, why all the fuss over what >seems like a very minor upgrade? I think the important thing here is the built-in PMMU. Apple should be getting a virtual memory system (not A/UX, but a *real* Mac one) done fairly soon. This will provide a box people can buy to run it on, without needing an upgrade. I suspect pretty soon the PMMU upgrade will be standard equipment for a Mac ][. Also, the 68882 provides a lot of speed for some applications; Apple might have decided not to wait on releasing the machine until they could push up the clock speed some more if they thought the doubled (or so) floating-point would broaden the market. Disclaimer: All of this is just my opinion. I expect nobody else shares it. I have no connection with Apple except as a customer. +----------------------------------+------------------------+ | Anton Rang (grad student) | "VMS forever!" | | Michigan State University | rang@cpswh.cps.msu.edu | +----------------------------------+------------------------+
wetter@tybalt.caltech.edu (Pierce T. Wetter) (10/01/88)
>seems like a very minor upgrade? So it has the 1.4-meg drive. IBM had that >a year and a half ago with the PS/2, and they have a reputation for using >only time-tested technology, whereas Apple is viewed as the technology >leader in microcomputers. Maybe leader in user-interface, but it seems like Ah, but the Apple drive can read Apple and IBM 1.44s and RELIABLY read 800s and 400s. Try reading a 360k disk in a 1.2meg floppy on an IBM possible, but not reccomended. 760s in a 1.44 aren't much better. ---------------------------------------------------------------- wetter@tybalt.caltech.edu pwetter@caltech.bitnet pwetter@caltech.edu ----------------------------------------------------------------- Weird theory #47: Islamic women can do kinky things with their ankles, that's why the Koran says they aren't supposed to reveal them in public.
daveh@cbmvax.UUCP (Dave Haynie) (10/04/88)
in article <747@cps3xx.UUCP>, usenet@cps3xx.UUCP (Usenet file owner) says: > In-reply-to: 128a-3aj@e260-3b.berkeley.edu's message of 30 Sep 88 22:24:09 GMT > A 68020 (arguably) does more work each cycle than an 80286. Also, > something else to watch is the memory access time. With high-speed > memory prices going up, putting a 30-MHz 68030 in your machine will > cost a LOT--not just the processor and main memory, but putting a > reasonable cache (say, 32-64K) of really high-speed memory in to avoid > wait states (disclaimer: I haven't seen a 68030 hardware manual, so I > don't know its memory rate/cycle time ratio). The '030 can run sustained memory cycles at two clocks per cycle, and burst memory cycles at one clock per cycle for up to three cycles. Apparently none of these features are used in the IIx, but from a chips alone point of view, an '030 can more than double the speed of the '020-'851 combination at the same clock rate. Another thing to consider when comparing 680x0 system to 80x86 systems is ".L". Or, put another way, WE get longword instructions, they don't under MS-DOS or OS/2. So a '386 machine running at 25MHz or so is still running only 16 bit instructions. That 32 bit bus isn't going to help all that much. All your 68000 code is already full of 32 bit wide instructions, so all 680x0 system get an immediate benefit from 32 bit wide memory. -- Dave Haynie "The 32 Bit Guy" Commodore-Amiga "The Crew That Never Rests" {ihnp4|uunet|rutgers}!cbmvax!daveh PLINK: D-DAVE H BIX: hazy "I can't relax, 'cause I'm a Boinger!"