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Questions tagged [intel]

Retrocomputing hardware and software created by Intel.

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74 votes
8 answers
25k views

Which Linux or BSD distributions do still support i386, i486 or i586 CPUs?

Unfortunately Debian kicked out Pentium 1 (i586) CPU support from its 32-bit PC port (named i386 for historic circumstances) for its next stable release Debian 9 Stretch. (Then again they complain ...
Axel Beckert's user avatar
18 votes
1 answer
3k views

Which undocumented 8085 instructions is Steven Morse referring to in "In The Beginning"?

In S. P. Morse's 1980 allegory, "In The Beginning", he writes And Intel said, "Let there be an 8085 with an oscillator on the same chip as the processor, and let an on-chip system controller ...
Evan Carroll's user avatar
  • 3,388
28 votes
2 answers
9k views

The start of x86: Intel 8080 vs Intel 8086?

Why is it said that all modern Intel processors of the x86 family are said to descend from the Intel 8086 and not the Intel 8080? From the Wikipedia article on the Intel 8086, The 8086 gave rise to ...
Evan Carroll's user avatar
  • 3,388
102 votes
6 answers
11k views

Were there 8086 coprocessors other than the 8087?

The 8087 math coprocessor for the 8086 (and descendants) nominally added floating point and transcendental (trigonometric and logarithmic) instructions to the 8086. Contrary to naive expectations, the ...
Euro Micelli's user avatar
  • 2,805
92 votes
10 answers
34k views

How much better was DEC Alpha than contemporaneous x86?

The DEC Alpha, released in 1992, seems like an early implementation of a fully 64-bit microprocessor architecture. Its release led to quite a bit of both marketing hype and genuine vendor support in ...
Brian H's user avatar
  • 60.8k
49 votes
2 answers
4k views

Did Windows NT 4 emulate x86 on non-Intel platforms?

I've been trying to find more information about non-Intel versions of Windows NT regarding x86 emulation but found very little about it. There is one sentence about it in the Wikipedia page but the ...
aybe's user avatar
  • 7,102
41 votes
3 answers
6k views

80286 can switch from real mode to protected mode - but why not back?

It's been a while, but I've read in a system programming book that you could switch your Intel 80286 CPU from the normal real mode to a more powerful protected mode. I clearly remember that they said ...
Byte Commander's user avatar
25 votes
3 answers
885 views

Why was segment register value scaled by such a small factor of 16 on i8086?

In 8086 architecture memory is addressed by segment:offset scheme, where the 20-bit linear address is formed as address=segment*16+offset. This looks needlessly complicated and doesn't allow to ...
Ruslan's user avatar
  • 1,444
18 votes
1 answer
1k views

Why is the 8254's default rate 18.2 Hz?

The Intel 8253/8254 timer, in its default configuration, triggers IRQ0 18.2 times per second. Why this strange rate, and not something like 60 Hz (to match the most common video refresh rate) or 100 ...
Mark's user avatar
  • 8,637
31 votes
10 answers
12k views

Should 486s have a heatsink?

I'm building a 486 computer. I plan on using a 100 MHz 486-DX4 that I have which I believe is about as fast as 486's went. The motherboard I will use (Socket 3) appears to support putting a heatsink ...
cbmeeks's user avatar
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29 votes
3 answers
7k views

Why did Intel abandon unified CPU cache?

When Intel introduced the 80486 in 1989, they included their first on-chip cache, ostensibly to compete better with Motorola, who had been including on-chip caches for 5 years (MC68020, 1984). Unlike ...
Brian H's user avatar
  • 60.8k
24 votes
2 answers
7k views

What was the last x86 CPU that did not have the x87 floating-point unit built in?

This Wikipedia page says the following: Most x86 processors since the Intel 80486 have had these x87 instructions implemented in the main CPU So the above quote implies that some CPUs that were ...
user12280's user avatar
  • 293
19 votes
2 answers
4k views

What are these weird long ISA slots on this 386 board? (not VLB)

In this image, you can see, from the right, a 16-bit ISA slot (occupied by a controller card), an 8-bit ISA slot, four more 16-bit ISA slots, and two of these strange slots that look like a 16-bit ISA ...
robbie's user avatar
  • 321
18 votes
5 answers
3k views

Was there ever a genuine "mainframe-on-a-chip" microprocessor?

In the 1980s and 90s, there was a fad among the IT industry press to dub the newest "hot" microprocessor on the market as being a "mainframe-on-a-chip". I have seen this fawning description applied to ...
Brian H's user avatar
  • 60.8k
15 votes
1 answer
2k views

What is the history of the Intel 8275 video controller?

The highly popular at the time build-it-yourself home computer Radio 86RK, designed in the Soviet Union, contained a rather mysterious video controller chip КР580ВГ75. It had a high end, feature rich ...
h22's user avatar
  • 413
13 votes
1 answer
2k views

Intel processor transistor type evolution

The Intel 4004 used MOS (metal–oxide–semiconductor) transistors. What has been the transistor types used in Intel processors onwards from the 4004 to 8085 to the x86 family of instruction set ...
Single Malt's user avatar
  • 1,859
12 votes
1 answer
2k views

Which endian was the Intel 4004?

The Intel 4004 had 4-bit buses and data words, but the program counter and code address space was 12 bits. Was the 4004 little endian (like all of Intel's later microprocessors and microcontrollers) ...
DrSheldon's user avatar
  • 16.3k
10 votes
2 answers
818 views

8086 pinout and address space limit

It is tempting to say - and I have said - that Intel made a mistake in the design of the 8086 and 8088, in going from 16 bit addresses to only 20 bits; if they had even shifted the segment registers ...
rwallace's user avatar
  • 62.4k