Questions tagged [intel]

For questions about retrocomputing hardware and software created by Intel

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12
votes
5answers
2k views

How and why did Intel make the PCI bus “CPU Agnostic”?

Intel invented the original 32/64-bit PCI bus in the early 1990s to replace the decade old ISA bus used in PC's. It was immediately popular (in comparison to Micro Channel or EISA), being both faster ...
4
votes
1answer
273 views

Instructions added with the Intel 80286 [closed]

The 80286 processor added these instructions: ARPL, VERR, VERW, LAR, LSL, SMSW, SGDT, SIDT, SLDT, STR, LMSW, LGDT, LIDT, LLDT, LTR, CLTS. To help understand how this was implemented I am looking for ...
13
votes
1answer
1k 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 ...
0
votes
1answer
113 views

Carry flag in the Intel 8008

Datasheet for the Intel 8008 CPU mentions that the Carry (C) flag is affected with the logic operations (AND, OR, XOR), but it does not make any sense. I believe Carry will be zeroed, but I have no ...
3
votes
1answer
302 views

Intel 8008 stack behavior

Intel 8008 CPU has an internal stack, implemented as an 8 x 14-bit scratchpad. How does it work exactly? Is there any "invisible 3-bit stack pointer"? I want to know what happens when the ...
4
votes
0answers
163 views

Undefined opcodes for the Intel 8008 CPU

What happens when I8008 CPU reads the "undefined" opcode (22h, 2Ah, 32h, 38h, 39h, 3Ah)? Are these opcodes evaluated as a NOP instruction, or lead to some side effects (RESET, etc). How many ...
-3
votes
2answers
270 views

Old Intel Pentium PC: am I an i586? Does Gentoo provide i586 packages? What else am I compatible with? [closed]

I've recently commenced revitalizing a very old PC. She's running an Intel Pentium, x86_64. I thought I'd give Gentoo a go because I've found it very appealing and as a Bedrock user I wanted to be ...
5
votes
1answer
263 views

Do all Intel Celeron processors support “FCOMIP”? [closed]

I am interested, did all Celeron processors support the FCOMIP instruction? I've made a compiler for my programming language and it uses FCOMIP for every floating-point comparison. I've noticed that ...
2
votes
1answer
156 views

Are all Slot 1 motherboards compatible with Coppermine?

I want to put together a Pentium III tower using a beautiful Coppermine SL3XL CPU I found with a Slot 1 form factor. However, I noticed that many slot 1 motherboards do not officially support ...
1
vote
2answers
284 views

What’s the last x86 CPU that didn’t place a limit on the size of a single instruction?

Although useless, it’s widely known the first Intel and derivative CPUs like the Z80 didn’t set a limit on the instruction size. This means that it was possible to fill the whole RAM/ROM with a single ...
40
votes
4answers
8k views

Is it true that Pentium III was faster than its successor Pentium 4?

My friend told me that earlier iterations of the Pentium 4 were not as fast as the Pentium III, but he didn't have sources. Is it true that the Pentium III was faster than its successor Pentium 4?
16
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2answers
2k 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 ...
20
votes
2answers
6k views

Why did Socket 3 have more pins than needed for the 486?

Intel's Socket 3, used for 486 processors, was a 19×19 pin grid array socket. However, all compatible processors, to my knowledge, used 17×17 PGA packages. What was the point of the extra pins around ...
8
votes
1answer
322 views

Which computers used the Intel 82786 graphics chips, and what sort of commercial success did that chip attain?

In the late 1980's, Intel offered the 82768 graphics chip, with specific support for windowed environments. I remember it being covered in Byte magazine, but don't remember seeing any applications of ...
8
votes
2answers
2k views

First x86 Software Development Manual

These manuals are now called “Intel® 64 and IA-32 Architectures Software Developer Manuals”, and the current version is 71. What was the original name of this manual and when was it released?
69
votes
7answers
18k views

How much better was DEC Alpha than contemporary 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 ...
11
votes
1answer
782 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 KR580VG75. It had a high end, feature rich ...
4
votes
5answers
2k views

Real mode flat model

I am interested in old Intel processors. I'll try to be as concise as possible. I have been studying both Jeff Duntemann's Assembly Language Step-by-Step - Chapter 4 and Modes of Memory Addressing on ...
4
votes
2answers
512 views

Need circuit - manual step-by-step clock for 8086/8088

I finally bought a ceramic 8086-1 (from ebay, from China - I'm not sure that it is not fake chip) and 8284 (it make the necessary synchronization signal for the processor from the crystal). Now I ...
0
votes
2answers
510 views

What 486 motherboard is this, with American Megatrends BIOS identifying is DPAQ-6156-043090-KF?

I've got an early 486 motherboard that doesn't seem to have a manufacturer name or FCC number on it and I'm having trouble identifying it. I've placed some photos of the motherboard in this Imgur ...
27
votes
3answers
6k 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 ...
4
votes
1answer
578 views

What was the first Intel x86 processor with “Base + Index * Scale + Displacement” addressing mode?

As the title says, what's the first x86 processor from Intel that supports the following addressing mode? mov %reg, 8(base, index, 4) ^^^^^^^^^^^^^^^^^ where the content of %reg will be ...
22
votes
2answers
5k 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 ...
4
votes
1answer
291 views

List of Intel microchips

Where could I find a list of all of the microchips released by Intel, including microprocessors, Rams, roms, storage devices. Etc. I have checked Wikipedia, and they have the processors, but not any ...
17
votes
1answer
2k 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 ...
8
votes
2answers
688 views

When did Intel undergo the SEX change?

I am reading the book "The 8086 / 8088 Primer Second Edition" by Stephen P Morse. In it on page 54, it says The 8086 provides instructions to facilitate the task of sign extension. These ...
13
votes
1answer
453 views

SYSENTER/SYSEXIT broken on Pentium Pro and Pentium II?

I was just What is linux-gate.so.1?, and it says this Intel recognized this problem early on and introduced a more efficient system call interface in the form of sysenter and sysexit instructions. ...
6
votes
1answer
745 views

What instructions for the 8086 and subsequent x86 CPUs are not available in Long Mode?

I know from this answer that, Modern x86 CPUs are binary compatible with 8086. You can literally run 8086 binaries on a modern PC, in real mode. (The species analogy is a stretch here, but works ...
6
votes
4answers
1k views

Reason behind “ASCII Adjust” instructions being ASCII and not BCD?

I'm just curious if there was ever other instructions that were more ASCII-centric than the CISC associated ones we're left with now? Specifically, all the Binary Coded Decimal (BCD) instructions ...
5
votes
3answers
2k views

Is BX the Base Address Register, and if so why?

I've seen a lot of posts on BX. I believe today, it's a "General Purpose Register". I'm confused at why people call it the Base Address Register, Why it's called the Base Address register, ...
7
votes
0answers
352 views

How was the Intel 80486 debugged? [closed]

How was the Intel 80486 (from 1989) debugged? I'm assuming it was written in some HDL language, like Verilog. However, how was testing and debugging of the CPU carried out? Were there several steps ...
9
votes
2answers
615 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 ...
9
votes
1answer
642 views

Is there any reason to chose ES, FS, or GS over the others in real mode?

The Wikipedia page on X86 Memory Segmentation says In real mode, the registers CS, DS, SS, and ES point to the currently used program code segment (CS), the current data segment (DS), the current ...
21
votes
2answers
5k 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 descent from the Intel 8086 and not the Intel 8080? From the Wikipedia article on the Intel 8086, The 8086 gave rise to ...
10
votes
3answers
1k views

Intel 8080 - Behaviour of the carry bit when comparing a value with 0

I'm in the process of writing an emulator for the Intel 8080. The description of the CMP instruction from Intel's 8080 programming manual (see page 20) says the following: The specified byte is ...
5
votes
2answers
356 views

Measuring CPU usage on an pSOS operating system

I have a piece of computer hardware in my lab that is running an Intel Celeron CPU with 300 MHz and 128k bytes of secondary cache. The hardware documentation says it's running an real time operating ...
30
votes
5answers
8k views

Are MS-DOS and Windows 9x vulnerable to Meltdown?

In an interesting crossover between current events and Retrocomputing, the vulnerability known as "Meltdown" was publicly disclosed on January 3rd 2018. The retro-computing tie-in is that this ...
13
votes
5answers
2k 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 ...
5
votes
1answer
286 views

Collection of older EPROM IC's

I acquired a collection of older EPROM IC's and am wondering what the rarity of them are or if they are rather common. Do people collect these items? 89142 NM27C512Q ~~ B9212 NM27C512Q ~~ B9312 ...
28
votes
9answers
10k 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 ...
3
votes
0answers
681 views

What are some programs known to take advantage of Intel MMX instructions? [closed]

Although MMX techology, introduced in 1997, is long superseded by SSE series of extensions, it's still included in every modern x86 CPU for backwards compatibility. What are some examples of ...
46
votes
3answers
8k views

What's the relationship between early 90s Pentium microprocessor and today's Intel designs?

My simplified understanding of the evolution of the Intel processors over the last 20 years is that the Pentium II and Pentium III architectures were sort of "dead-ends", and today's Intel processors ...
10
votes
2answers
1k views

When specifying Intel 80x86 instruction execution time, what is included in the cycle count?

I'm looking at this summary of the Intel x86 integer instruction set (though the same data seems to have been published in a number of places), which gives instruction timings on a per-instruction-...
92
votes
6answers
9k 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 ...
21
votes
12answers
4k views

Were people building CPUs out of TTL logic prior to the 4004, 8080 and the 6800?

I've just finished reading Charles Petzold's book, Code: The Hidden Language of Computer Hardware and Software. In it Charles explains building relays into gates, gates into logic components, and ...
55
votes
5answers
13k 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 ...
3
votes
2answers
253 views

IBM PS/2 Model 53 Not Powering On

I bought a PS/2 with the intent of robbing it's case for a restomod project, but since that is on the backburner right now I decided to see if it would work. When I flip the power switch, the PSU ...
16
votes
1answer
942 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 ...
24
votes
3answers
719 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 ...
6
votes
3answers
2k views

LCD Displays with the Intel 8080

A colleague of mine mentioned that in college he wrote a slot machine program on an Intel 8080 using an LCD display. What kind of display communication protocol existed on the Intel 8080? How was ...