Mailinglist Archive: opensuse (3337 mails)

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Re: [Fwd: Re: [SLE] Real Numbers representation in Tcl language]
  • From: "John E. Perry" <j.e.perry@xxxxxxx>
  • Date: Thu, 13 Apr 2006 09:03:07 -0400
  • Message-id: <443E4C0B.1050208@xxxxxxx>
Greg Wallace wrote:

When you say "mainframes didn't have floating-point hardware ...", how far
back in the mainframe world are we speaking? For example, did the IBM 360
have floating point hardware, or did that not come along until the 370 or
30xx machines?

Mainframes in the '60's, '70's, and early '80's were built with small-scale and medium-scale integrated circuits -- AND, OR, registers, maybe an occasional special chip of the same level of complexity. Intel at the time was leading the world in integrated circuit complexity.
The 4004, a 4-bit microprocessor chip, came out in 1971, and was by far the most complex chip ever built at the time. The 8087, the first math coprocessor, came out in 1980, and was again the most complex chip ever built. The 80486DX, the first processor with on-chip floating-point, came out in 1989. Again, the most complex chip ever built.

None of the mainframe companies were anywhere near the microprocessor companies' levels of integration, as far as I know, until the late '80's and '90's. That's why they built machines that could do little or no more, but cost millions of dollars. There were comments when the IBM PC came out in 1981 that they probably used the 8087 as the basis for the PC because the 68K machine they'd already built cost a tenth the price of their low-end mainframe, and was substantially faster :-). I don't know what was in the IBM managers' minds, but I do know they had a 68K machine that was much faster than the PC: I had one at work.
At home, in 1984, I bought a $400 Radio Shack TRS-80 Color Computer, which ran Microsoft Basic (the same software as on the PC) more than twice as fast as the $5000 IBM PC my colleague bought :-). It used an 8-bit Motorola 6809 processor.

John Perry


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