61–64 of 64 posts
I guess its market window might have been too narrow. It seems like if you wanted the performance back then, you might even go without a battery, so using a desktop CPU without the power-management special tricks is no big deal.
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Love the post! Some DOI and Bitsavers links are broken (linking to righto.com or 404s). Also, where can I find "Automatic Place and Route Used on the 80386"? DDG only contains one result: this post.
There was some discussion of the automatic placement in this panel interview. If I remember correctly, the software that performed the placement was written by a graduate student who debugged it from a terminal at his dormitory. It was one of many project decisions on the i386 that management would have absolutely stopped had they been made aware. https://www.computerhistory.org/collections/catalog/10270201... "386 i…
Feature wise, the ARM1 is probably more comparable to the Motorola 68000 from 1979, both have ~16 32bit registers, no MMU and no instruction prefect queue. The ARM1 does have a full 32bit ALU compared to the 68000's 16 bit ALU, and a full 32bit barrel shifter, compared to the 68000's 1 bit shifter.
But the 68000 is still 68,000 transistors (hence the name). So not only is the ARM1 achieving about the same level of functionality with under half the transistors, but it can execute instructions significations faster.
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Thanks for your kind comments! Personally, I'd say that the IBM System/360 (1964) was the first widespread and influential 32-bit architecture. The Motorola 68000 (1979) also deserves a mention for its use in the Macintosh. (And I'll argue with anyone who says it wasn't a real 32-bit processor :-) But, yes, the 386 started the 32-bit x86 architecture on most (non-phone) computers today.
Excellent points! System/360 is indeed interesting because (if my memory serves me) it was one of the first computational architectures to implement microcode (also, if I recall correctly, the necessity of updating of this microcode was one of the reasons that floppy drives were invented...) I'm also a fan of the Motorola 68000 -- I used to have an Amiga 1000 "back in the day". I'd choose it over any 8 or 16 bit CPU…
It didn't, but the real issue wasn't that it didn't have one.
It was that it didn't support one. Specifically, the stack frame the 68000 pushes on bus error lacks the information to allow recovery (retrying).
68010 solved this. Many UNIX workstations are based on the 010, some use Motorola's MMU chip, most use custom designs.
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There was some discussion of the automatic placement in this panel interview. If I remember correctly, the software that performed the placement was written by a graduate student who debugged it from a terminal at his dormitory. It was one of many project decisions on the i386 that management would have absolutely stopped had they been made aware. https://www.computerhistory.org/collections/catalog/10270201... "386 i…
> Did the i386 really have additional features Here are a few: - > 26 bit address space - multiplication in hardware - more complex instructions - backwards compatibility with the 80286 - on-chip MMU - support for a FPU > that justify an order of magnitude? I wouldn’t know. Backwards compatibility certainly is high on the list because, when it was released, many users had fairly high investments in commercial softwar…
With the 8086, sure. v86 got you covered.
With 80286? Not really. It might have some of the instructions, but it does not support 286's protected mode.