Talk:Intel 80386

Models and variants, content error?

It says the i386DX was produced with about 104mm^2 die size in the CHMOS III process and later with about 39mm^2 die size in the CHMOS IV process. For the i386SX it says it was produced with the CHMOS IV process and with about 104mm^2 die size. Are you sure the die size and/or process for the SX variant is correct? It doesn't seem to add up for me, at least.

178.24.193.37 (talk) 16:51, 11 May 2010 (UTC)

Most Important Design Choice

I don't understand how keeping the flat memory model was such a significant design choice. Upon further research, it seems that all preceding Intel chips also featured a flat memory model. —Preceding unsigned comment added by 216.27.163.78 (talk) 02:46, 21 February 2009 (UTC)

Earlier chips supported only 64KB of flat/linear/continous addressing; the 386 was the first chip which had this extended to 4GB, i.e. 65536 times as much, a very significant difference. 83.255.39.24 (talk) 20:40, 23 February 2009 (UTC)

In order to address all of the memory available in the computer using an 8086 or 80286, you had to use a segment register, which would be multiplied by 16 and added to the address register. So in order to access any given memory location within, say, the first megabyte of RAM, you need to do some maths to present the CPU with a segment:offset. The 386 provided a method of accessing all the available RAM by extending the address pointers beyond 16 bits. - Richard Cavell (talk) 06:51, 1 July 2009 (UTC)

Release

I've seen sources that say the chip was released in 1985. [[1]]. Was it really 1986 or was it 1985? Timbatron 21:42, 25 December 2005 (UTC)

The chip taped-out in October 1985 (I was there). It was not "released" until (IIRC) late 1986, as at the time there was a long lead-time between tape-out and public availability. -- Gnetwerker 08:08, 3 February 2006 (UTC)

Sorry to respond to such an old comment, but is there any citations to confirm this? Everything I've read on the Intel website points to 1985 not 1986. --Android Mouse 00:03, 15 July 2007 (UTC)

Sources

"Intel decided against producing the chip before then, as the cost of production would have been uneconomic." What is the basis for this assertion? The chip wasn't designed until Oct '85, this implies otherwise. -- Gnetwerker 08:08, 3 February 2006 (UTC)

Customers

I think it is significant that the first major customer was Compaq, then not a large company, rather than IBM. While I "know" this (from being at Intel), I don't have a source. Anyone? (P.s. -- The Compaq page says all of these things without attribution.) -- Gnetwerker 08:11, 3 February 2006 (UTC)

SX-DX

Does anyone know what SX and DX stand for? I heard once "Single eXecution" and "Double eXecution". But I've never seen that confirmed. warpozio 14:04, 27 March 2006 (UTC)

SX and DX means very different things, depending on processor's generation. 80386SX internally is identically the same as DX (fully 32-bit), but it has 16-bit data bus, which slowed down it's memory access performance comparing to 80386DX, which had 32-bit data bus. In this matter it's similar to Motorola 68000, which is also a 32-bit processor internally (32 bit addressation, registers, arithmetic), but also has 16-bit data bus. It was done to minimize the costs of motherboards - 68000 was out much earlier than 80386SX. Also, first 80386 of course has 32-bit data bus, thus is was the "DX", yet it wasn't called so, because 80386SX and separation between SX and DX was introduced later.

In the 486 generation processors SX versions doesn't have built-in FPU. Of course 80386 never has integrated FPU, thus 486SX at the same frequency is something like faster 80386DX (faster due architectural advances - pipelined ALU and so on). Yet, AMD has managed to produce 80386DX working at quite high frequencies (40Mhz), thus is often was faster than 486SX with lower freqs like 25Mhz.

SX and DX are mostly marketing features, which are introduced to separate lower and upper segments of market. In such meaning they are something like "Celeron" and "Pentium" trademarks used todays. Though different generations of processors use different ways to "cripple" the performance in low-cost models.

You didn't read the question, Mr Unsigned. You answered a question that was in your head. The gentleman wanted to know what the letters DX and SX stood for. You let him down, and that upsets me. Lupine Proletariat 14:55, 18 May 2006 (UTC)

SX - Single Word External (16-bit data bus) DX - Double Word External (32-bit data bus). —Preceding unsigned comment added by 89.243.46.113 (talk) 20:34, 6 November 2007 (UTC)

...and also a contraction of SimpleX and DupleX, which could be in relation to having a bus that was the same size as, or double that of the previous-gen CPUs? 193.63.174.10 (talk) 15:10, 27 October 2010 (UTC)

80287

Assembler manuals claims that original 80386 could work with 80287 processor - to save one's investments, or to allow intemediate price-and-perfomance level between FP-less sole 80386 and expensive 80386+80387 pair

Multiply bug

OK, why delete that section? It's significant - the first Intel '32 bit' CPU didn't, you know, actually work and Intel ended up stamping thousands of chips '16 bit only'. Several important programs (eg Windows) checked for this. Lovingboth 22:30, 29 October 2006 (UTC)

Third generation x86 processor?

Isn't 80386 be the fourth generation x86 processor (8086, 80186, 80286 and then 80386)? Or is there some reason why one of these should not be regarded as a generation? Even though this article is about computing, I guess the 8086 can't be counted as zeroth generation... 213.216.199.30 21:20, 13 February 2007 (UTC)

To my understanding, the 8086 and the 80186 are both considered chips in the first generation, similar to how the Pentium II and III are both considered sixth generation chips. Suigi 05:05, 14 February 2007 (UTC)

It would be more natural to regard only 8086 (1978) and 8088 (1979) as first generation chips, but both 80286 (1982) and 80186/188 (1982) as second generation designs. 80186 and 80286 have a great deal in common technically. /HenkeB 23:47, 18 March 2007 (UTC)

That makes more sense. It still means that the 80386 is the 3rd generation chip, thus resolving this issue. Suigi 01:12, 19 March 2007 (UTC)

Yes. /HenkeB 15:48, 19 March 2007 (UTC)

Socket

The summary box states that the 386 is a 68 pin CPU. I am fairly sure (looking at a summary from Intel docs) that the 386 DX was offered in a 132 pin PGA or PQFP format. The coprocessor, the 387, was 68 pin. Also, the 386 SX may have been offered in a 68 pin format since it had only a 16 bit external data bus.

Blackberry

Should it be noted that this chip was still used in RIM Blackberries until recently? —Preceding unsigned comment added by 86.164.161.165 (talk) 14:15, 25 December 2007 (UTC)

Disambiguation needed

A disambiguation page is needed for "i386". A search querie for this term directs to this page (the 80386 page). The term "i386" also refers to a directory used in Windows operating systems that contains files used to create an installation disk. The directory is not related to the processor used on the host machine. WWriter (talk) 22:06, 4 February 2008 (UTC)

Firstly, the directory on a Windows install disk does refer to the processor architecture. Secondly, is the directory on a Windows install disk worthy of its own article? - Richard Cavell (talk) 06:55, 1 July 2009 (UTC)

Typo found

Intel i386 SL processon <--- Should end in R, but being a newbie I can't figure out how to get at it... It's the text for the image of the SL processor I believe.

fixed. -75.69.164.125 (talk) 21:43, 21 March 2008 (UTC)

i386EX and Hubble Space Telescope

This page says that the i386EX was used in the Hubble Space Telescope. The Hubble Space Telescope was launched in 1990 (but didn't work until 1993 when the corrective mirrors were installed), but the i386EX did not come out until 1994. How can this be? Was the i386EX added on a servicing mission? —Preceding unsigned comment added by 24.167.184.128 (talk) 05:10, 22 September 2008 (UTC)