Article 16859 of comp.sys.amiga.hardware: Path: orstcs!rutgers!cs.utexas.edu!uunet!tnc!m0154 From: m0154@tnc.UUCP (GUY GARNETT) Newsgroups: comp.sys.amiga.hardware Subject: Re: OK, Once again...80486 vs. 680x0 Message-ID: <1000@tnc.UUCP> Date: 1 Jan 92 21:49:32 GMT References: Reply-To: m0154@tnc.UUCP (GUY GARNETT) Distribution: usa Organization: The Next Challenge, Fairfax, Va. Lines: 129 OK, I'll stick my neck out on this one ... Scott R Myers asks for a comparison between a PClone (80486/33Mhz) and a "comprable" amiga. First off, what do you intend to *USE* the machine for? PClones and Amigas have radically different processors, machine architectures, and operating systems, and are optimized for different types of applications. 1) Crunchons A friend of mine uses the term "Crunchon" as a unit of relative computer horsepower; this is a subjective term, so take everything with a grain of salt :) A quick rundown of the Intel and Motorolla processor familys is in order. Intel developed the 80x86 series of processors as logical successors to the processors that (arguably) started the personal computer revolution, the 8080 and its successor, the 8085. The architecture was designed to be very similar to these early processors, so that hardware designers and programmers would have as gentle a learning curve as possible. The 8086 was a 16 bit processor (16 bit registers and 16-bit bus) with a 20 bit address space (4Mb) provided by a clever memory segmentation scheme (which essentially allowed you to have up to 4 64k "windows" into this 4Mb address space). The 8088 was an 8086 with an 8 bit bus (but the same 16 bit registers) and a 1Mb address space. If it were introduced today, Intel would probably call an 8088 a 80186SX. The 8086 became the 80186 with a few minor changes. From here came the 80286 (which added a new operating mode to help run sophistocated operating systems and better manage the memory, now extended to 16Mb). The 80386 increased the address space to 2Gb, increased the registers and bus to 32 bits, and added a memory management unit and virtual 8086 modes to provide even more operating system flexability. The 80486 is a streamlined 80386 with the math co-processor and other auxiliary functions brought on board; it mainly provides better performance over the 80386. Intel's 80386SX is a 16-bit bus (but retains the 32 bit registers) version of the 80386; it was introduced primarily to kill off the 80286 (which had been second-sourced to other manufacturers). The 80486SX is a deliberatly crippled version of the 80486, and was introduced to attempt to kill off AMD's 80386 clones. On the Motorolla side, the 680x0 family was originally designed to be a family of processors designed from the ground up to run high-level language code (like Pascal or C) and run sophisticated operating systems. All 680x0 processors have 32-bit registers and compute 32 biyt addresses, with a "flat" address space (no segmentation, a program can use as much of the address space as it needs). The 68000 was the first design, and had a 16-bit external bus (but retained the 32-bit internal bus), and a 24-bit address space (16Mb; the other address lines were left un-connected, and internally all 32 bits are used). The 68008 was an 8-bit version of the 68000. The 68010 is pin-compatible for the 68000, and offers improved microcode (about 10% faster, and a new operating mode to help with sophisticated operating systems). The 68020 has a full 32-bit bus and a 2Gb address space; a MMU and a Math Co-processor were available options. The 68030 brought the MMU on-board the main processor, and improved performance and added some improved instructions. The 68040 brought the math co-processor on board and further sped up the processor. Rough Comparison Chart <<< Slower ----- Faster >>> Intel: 8088 8086/80186 80286 80386 80486 Moto: 68008 68000 68010 68020 68030 68040 2) Operating System The Amiga runs a relatively sophisticated real-time, multitasking operating system, and it has for all its life. While this made the initail learning curve more difficult (especially as compared to MsDOS and the MacOS/Finder of the time) most Amiga programmers have already come to grips with problems that Dos and Mac programmers are just now facing. MsDos is a single-tasking operating system ultimately derived from the grand-daddy of them all CP/M. And it is showing its age. Windows runs "on top of" Dos, and Windows version 3 is probably most comparable to AmigaDOS. OS/2 and Windows/NT are both attempts at building a new operating system for the PClone hardware; in some ways they are more sophisticated than AmigaDOS (primarily in the area of memory protection). Subjectively speaking, for most tasks using the respective GUI operating systems, a 68010-based Amiga 1000 seems about as responsive (in terms of opening windows, moving things about, and so on) as a 25Mhz 80386 running Windows 3 and Norton Desktop. My Amiga takes about 3 minutes to cold-start (this includes loading the Kickstart disk, and copying another 800k of system disk into the recoverable RAM disk), measured from the insertion of the kickstart disk to when my CLI shell opens on the workbench. My 80386 PClone takes about a minute to start-up from a cold-start to the DOS prompt (from a hard disk), and another minute and a half to go from the DOS prompt into Windows and the Norton Desktop. Not too much difference, except the Amiga is booting off of floppies, while the PClone is running off of a fast SCSI hard disk. For multimedia work, or graphics programming at common Amiga or VGA resolutions, an Amiga 3000 with a 68040 accellerator will probably beat the pants off of any available PClone with a VGA display. MOst of this is the display bottleneck in the VGA, and part is that the 68040 is slightly (10% to 50%, depending on the application) faster than a 80486 at a similar clock speed. On the other hand, the 80486 is probably cheaper, and will be just as fast (or thereabouts) at non-graphics applications. For the price difference, you just might be able to get a TIGA graphics board which would more than even out the graphics performance. 3) Recommendation: Find *THE* piece of software that you absolutely must have to get your work done, and buy the computer that runs it. If you just want to hack around, read about the processor and machine architectures, and the two operating systems, and then decide which one is more fun (personally, I perfer the Amiga). Wildstar "... if you choose not to decide, you still have made a choice." -- Rush -- The Next Challenge - Public Access Unix in Northern Va. - Washington D.C. 703-239-8993 or 703-764-0527 To log in for trial and account info.