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Comment Re:Why is this x86 and not 64bit? (Score 1) 87

the Motorola 68000 series (the 68000 and 68010 had a 24-bit address bus and a 16-bit data bus, and a 16-bit ALU for data operations; the instruction set had 32-bit registers and arithmetic instructions and 24-bit physical addresses, extended to 31-bit physical addresses with the 68012 and 32-bit physical addresses with the 68020 and subsequent processors, which had 32-bit internal data paths),

And the 68008 had an 8-bit data bus, but was internally like a 68010, with 32-bit registers and arithmetic instructions and a 16-bit ALU for data operations.

On the other side, the 32-bit original Pentium had a 64-bit external data bus.

So you have the external bus width, the internal data path width, and the instruction set width(s) (registers, arithmetic instructions, addresses, etc.), which can vary somewhat independently; it might be appropriate use the external bus width as an indicator of the bit width of the processor when designing designing support chips and attaching peripherals, but it's a lot less relevant when discussing programming the processor (especially if you're not writing software for that particular processor but are writing software for processors with that version of the instruction set).

Comment Re:Why is this x86 and not 64bit? (Score 1) 87

What defines the bit width of an instruction set isn't connected to data bus width, as different implementations of the same instruction can have different data bus widths.

That's news to me. When I doing electronics as a teenager in the 1980's, an 8-bit processor had eight data lines, a 16-bit processor had 16 data lines, and a 32-bit processor had 32 data lines. I recently saw a 64-bit microcontroller that implemented one-half of the data bus (32 bits) as four 8-bit serial ports (four pins). I'm not sure if that's a four-bit or two-bit design.

Again, there's the width of the processor's external bus, the width of the processor's internal signal paths, and the width of the registers and instructions of the instruction set the processor implements. Nothing ties the first two of those to the third of those, as evidenced by various models of the System/360 series (the I/O interface had 8 "bus in" lines, 8 "bus out" lines, and various control lines; the processors had internal signal paths ranging from 8 to 32 bits for integer and address operations; the instruction set had 32-bit general-purpose registers and arithmetic instructions and 24-bit physical addresses), the Motorola 68000 series (the 68000 and 68010 had a 24-bit address bus and a 16-bit data bus, and a 16-bit ALU for data operations; the instruction set had 32-bit registers and arithmetic instructions and 24-bit physical addresses, extended to 31-bit physical addresses with the 68012 and 32-bit physical addresses with the 68020 and subsequent processors, which had 32-bit internal data paths), and the 8086/8088 and 80186/80188 (same processor core in the 86 and 88 variants, just a different external bus; the instruction set had 16-bit registers and arithmetic instructions).

It's about more than just the electronics; it's about the software, and that mainly involves the instruction set, with the external and internal data widths being a performance issue rather than a pure functionality issue.

So, from the 1960's (and maybe earlier) to the present day, you could, for example, have a processor with an 8-bit data bus and 16-bit, 32-bit, or 64-bit registers and arithmetic instructions and 16-bit, 24-bit, 32-bit, and 64-bit physical/virtual addresses.

The 8088 was a processor with an 8-bit data bus and everything else 16-bit; as Intel's manual says, "The 8086 and 8088 are closely related third- generation microprocessors. The 8088 is designed with an 8-bit external data path to memory and I/O, while the 8086 can transfer 16 bits at a time. In almost every other respect the processors are identical; software written for one CPU will execute on the other without alteration." They also note that "The high performance of the 8086 and 8088 is realized by combining a 16-bit internal data path with a pipelined architecture that allows instructions to be prefetched during spare bus cycles.", so both are internally 16-bit implementations of the 16-bit instruction set.

Comment Re:Why is this x86 and not 64bit? (Score 2) 87

Which weren't x86 processors.

That depends on what you consider to be an 8-bit processor. Based on other comments, the devil is in the details regarding the 8086/8088 processors. I pointed out to another poster that the 80186 had an internal multiplexed 20-bit bus and available with an 8-bit or 16-bit external data bus. Unless someone changed the definition for a processor in the last 40 years, the data bus determines bit-width of a processor.

If so, then it's an 8-bit processor that implemented a 16-bit instruction set, then, just as the IBM System/360 Model 30 was an 8-bit processor that implemented a 32-bit instruction set and the Motorola 68000 was a 16/32-bit processor that implemented a 32-bit instruction set. From the programmer's point of view, the 8088 had 16-bit registers, 16-bit arithmetic instructions, and 16-bit "flat" addresses, just as the 8086 did.

What defines the bit width of an instruction set isn't connected to data bus width, as different implementations of the same instruction can have different data bus widths. "x86" isn't a processor, it's a family of instruction sets, including the original 16-bit 8086/8088 instruction set (with updates in the 80186/80188), the protected-mode 16-bit 80286 instruction set, the 32-bit IA-32 instruction set, and the 64-bit x86-64 instruction set. There was no 8-bit x86 instruction set.

Submission + - New app turns smartphones into worldwide seismic network

Saeed al-Sahaf writes: UC Berkeley wants your phone to help detect earthquakes. The school has released an Android app, MyShake, that uses your phone's motion sensors to detect the telltale signs of tremors and combine that with the data from every other user. Essentially you become part of a crowdsourced seismic station network. Once enough people are using it and the bugs are worked out, however, UC Berkeley seismologists plan to use the data to warn people miles from ground zero that shaking is rumbling their way. An iPhone app is also planned.

Comment Re:Too bad they pushed Love out (Score 1) 225

To which version of System V are you referring? The original one, SVR2, SVR3, or SVR4 and later?

The entire project (or at least from the start through the initial deployment of SVR4.)

The entire project, starting with SVR1? What "major UNIX vendors" other than AT&T were involved in the "re-implementation" (which wasn't a from-scratch reimplementation - it was an evolution from V7+the PWB-derived UNIX/TS) - "involved" in the sense of "developing code that went into System V" rather than "licensing the code from AT&T and doing their own stuff to it"?

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