Talk:Intel 8086

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Sources

The article seems to be lacking sources. A reference to the original 8086 intel doc would be cool, maybe somebody has a link? anton

Incorrect information

I corrected the '1989' introduction year to 1978. It seems that somebody wrote wrong information.

by sending out the appropriate control signals, opening the proper direction of the data buffers, and sending out the address of the memory or i/o device where the desired data resides

Also by AMD

AMD created this processor type too. It has number P8086-1 has a AMD logo and also (C) Intel 1978. I can make a picture of the chip and add it to the article.

Please clarify

The 8086 is a 16-bit microprocessor chip designed by Intel in 1978, which gave rise to the x86 architecture. Shortly after, the Intel 8088 was introduced with an external 8-bit bus, allowing the use of cheap chipsets. It was based on the design of the 8080 and 8085 (it was assembly language source-compatible with the 8080) with a similar register set

Does the final sentence refer to the 8088 or the 8086? At first glance, it continues the info on the 8088, but upon consideration, it seems more likely to refer to the 8086. Is this correct? It's not too clear.

Fourohfour 15:15, 9 October 2005 (UTC)[reply]

It refers to both, 8086 and 8088 are almost the same processor, except that 8086 has 16 bit external data bus and the 8088 has 8 bit external data bus and some very very small diferences. both where based on 8080's design. --200.11.242.33 17:20, 18 October 2005 (UTC)[reply]

In "Busses and Operation", it states "Can access 2²⁰ memory locations i.e 1 MiB of memory." - While the facts are correct, the "i.e." suggests that they are directly related. The 16 bit data bus would imply an addressable memory of 2MiB (16 x 2²⁰), but the architecture was designed around 8 bit memory and thus treats the 16bit bus as two separate busses during memory transfers. 89.85.83.107 11:08, 20 March 2007 (UTC)[reply]

The 8086 was not "designed around 8 bit memory" (however 8088 was), but each byte has its own address (like in 8-bit processors). Therfore 2²⁰ bytes and/or 16-bit words can be directly addressed by both chips; the latter are partially overlapping however, as they can be "unaligned", i.e. stored at any byte-address. /HenkeB 20:11, 21 May 2007 (UTC)[reply]

first pc?

is this the first "pc" microprocessor? I think so, in which case it should be noted, although I expected to find a mention to the first, whether it's this or a second one. —The preceding unsigned comment was added by 81.182.77.84 (talk • contribs) .

The first IBM PC used an Intel 8088, which is (as far as I know) effectively a slightly cut-down 8086 with an 8-bit external data bus (although internally still 16-bit). So that fact should probably be noted in the article. Fourohfour 18:27, 10 March 2006 (UTC)[reply]

also, for comparison, I'm interested in the size and speeds of pc hard-drives at the time, ie when it would have been used by a user -- I had thought around 10 MB but in fact if it can only address 1 MB (article text) this seems unlikely. Did it even have a hard-drive? a floppy? anything? —The preceding unsigned comment was added by 81.182.77.84 (talk • contribs) .

You're confusing things here. When it talks about "memory" it means RAM. Hard drives are different, they are I/O devices and the processor communicates with them via programmed input/output (PIO) or DMA. The 20-bit / 1Mbyte limitation is only for RAM. Mystic Pixel 07:36, 8 June 2006 (UTC)[reply]

Disagree

I don't think the two articles should be merged. After all, the one talks about the 8086 itself while the other about the general architecture my_generation 20:06 UTC, 30 September 2006

I think merging the articles is a good idea. The Intel 8086 set the standard for microprocessor architecture. Look at the Intel 8086 user manual (if you can find it on eBay or Amazon) and you'll see the information that's included in both of these articles. It would be easier to have all that information in just one. In answer to the above disagreement, you can't describe the 8086 without describing its architecture.

There's nothing wrong with duplicating information that's already in the manual, but Microprocessor 8086 is poorly written and misnamed. An encyclopedia article isn't going to explain how to program a µP and theoretical details are out of place here. Is there anything in particular you think should be moved to Intel 8086? Or perhaps remove the duplicate information and give Microprocessor 8086 a name which is clearer (or at least grammatical)? I'd like to remove that page and just have it redirect. Potatoswatter 06:46, 21 November 2006 (UTC)[reply]

I second what Potatoswatter said. (I thought the 8086 manual was available, but it doesn't seem to be. That's really weird, the 80186 manual is all over the place. Hmm.) Mystic Pixel 05:10, 22 November 2006 (UTC)[reply]

Not a bug?

This comment was in the "bugs" section: Processors remaining with original 1979 markings are quite rare; some people consider them collector's items.

This didn't seem to be related to a bug, so I moved it here. - furrykef (Talk at me) 06:38, 25 November 2006 (UTC)[reply]

It was referring to the previous statement that such processors were sold with a bug. I'm putting it back. Potatoswatter 15:04, 25 November 2006 (UTC)[reply]

What exactly was the bug that was in the processor? More information could be given than just a "Severe interrupt bug". --SteelersFan UK06 03:10, 8 February 2007 (UTC)[reply]

Processor Prices

Does anyone knows how much was the price of an 8086 processor when launched as a per unit or per thousand units? I think it is an important information that is missing.--201.58.146.145 22:21, 13 August 2007 (UTC)[reply]

I don't recall a onesy price for the CPU alone. I do recall that we sold a box which had the CPU, a few support chips, and some documentation for $360. That was an intentional reference to the 8080, for which that was the original onesy price. I think the 8080 price, in turn, was an obscure reference to the famous IBM computer line, but that may be a spurious memory. For that matter, I'm not dead sure on the $360 price for the boxed kit, nor do I recall the name by which we called it at the time. I have one around here somewhere, as an anonymous kind soul left one on my chair just before I left Intel for the second time. —Preceding unsigned comment added by 68.35.64.49 (talk) 20:48, 26 February 2008 (UTC)[reply]

iAPX 86/88

The Intel manuals (published 1986/87) I have use the name iAPX 86 for the 8086, iAPX 186 for the 80186 etc. Why was this? Amazon lists an example here http://www.amazon.com/iAPX-186-188-users-manual/dp/083593036X John a s (talk) 23:04, 6 February 2008 (UTC)[reply]

Around the time the product known internally as the 8800 was introduced as the iAPX432 (a comprehensive disaster, by the way), Intel marketing had the bright idea of renaming the 8086 family products.

A simple 8086 system was to be an iAPX86-10. A system including the 8087 floating point chip was to be an iAPX86-20.

I (one of the four original 8086 design engineers) despised these names, and they never caught on much. I hardly ever see them any more. But, since Marketing, of course, controlled the published materials, a whole generation of user manuals and other published material used these names. Avoid them if you are looking for early-published material. If you are looking for accuracy, avoid the very first 8086 manual, than which the second version had a fair number of corrections--but nearly all those were in long before the iAPX naming.

Peter A. Stoll —Preceding unsigned comment added by 68.35.64.49 (talk) 20:43, 26 February 2008 (UTC)[reply]

Embedded processors with 256-byte paragraphs

The article says:

According to Morse et al., the designers of the 8086 considered using a shift of eight bits instead of four, which would have given the processor a 16-megabyte address space.

It seems some manufacturers of 80186-like processors for embedded systems have later done exactly this. That could perhaps be mentioned in the "Subsequent expansion" section if reliable secondary sources can be found. So far, I've found only manufacturer-controlled or unreliable material. Paradigm Systems sells a C++ compiler for "24-bit extended mode address space (16MB)"[1] and lists supported processors from several manufacturers:

Genesis Microchip: I can't find any model number for a processor of theirs supporting this mode. Later bought by STMicroelectronics.
Lantronix: DSTni processors, spun off to Grid Connect. DSTni-LX Data Book[2] says the processor samples pin PIO31 on reset to select 20-bit or 24-bit addresses. DSTni-EX User Guide[3] calls the 4-bit shift "compatible mode" and the 8-bit shift "enhanced mode".
Pixelworks: ImageProcessor system-on-a-chip, perhaps including the 80186-compatible microprocessor in PW164[4]. Pixelworks licensed[5] an 80C186 core from VAutomation but only 20-bit addressing is mentioned there.
RDC Semiconductor: R2010, always 8-bit shift.[6]
ARC International: acquired[7] VAutomation, whose Turbo186 core supported a 256-byte paragraph size.[8][9]

85.23.32.64 (talk) 23:52, 11 July 2009 (UTC)[reply]

maximum length of instruction

The infobox at the top of the article shows the instruction encoding as "Variable (1 to 16 bytes)". Is there some reference for this? IIRC, earlier processors allowed very long instructions to be constructed with redundant prefixes, but the 80386 raises an exception if the instruction exceeds 15 bytes. That number is needed for e.g. lock xor dword [es:eax+eax+0x12345678], 0x87654321 if the default address and operand sizes are 16-bit. So, has the limit been raised to 16 bytes, and when did that happen? 85.23.32.64 (talk) 00:47, 15 August 2009 (UTC)[reply]