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Debugger changes for improved 32-bit support

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Jeff Parsons 2015-02-28 11:55:55 -08:00 • committed by jeffpar
commit f50612e7ca
21 changed files with 3581 additions and 2949 deletions
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4
blog/2015/02/22/README.md
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@ -10,12 +10,12 @@ post it.
A Compaq DeskPro 386 test configuration is displayed below. It's located at:
> [/devices/pc/machine/compaq/deskpro386/ega/1152Kb/](/devices/pc/machine/compaq/deskpro386/ega/1152Kb/)
> [/devices/pc/machine/compaq/deskpro386/ega/2048Kb/](/devices/pc/machine/compaq/deskpro386/ega/2048Kb/)
The configuration doesn't run, and the debugger can't disassemble 80386-specific code yet, but this is what I will be
using to test and debug my changes over the next few months.
[Embedded DeskPro 386](/devices/pc/machine/compaq/deskpro386/ega/1152kb/machine.xml "PCjs:deskpro386-ega-1152k::uncompiled:debugger")
[Embedded DeskPro 386](/devices/pc/machine/compaq/deskpro386/ega/2048kb/machine.xml "PCjs:deskpro386-ega-2048k::uncompiled:debugger")
*[@jeffpar](http://twitter.com/jeffpar)*
*February 22, 2015*

64
blog/2015/02/23/README.md
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@ -92,8 +92,8 @@ According to [OS/2 Museum](http://os2museum.com) proprietor Michal Necasek, the
Fortunately, my 80386-B1 CPU is also marked with a "ΣΣ" (double sigma), which is how Intel marked
parts that tested safe for 32-bit multiplication. Some 80386 CPUs suffered from a manufacturing defect that
could occasionally result in multiplication errors; defective parts that Intel caught were marked with "16 BIT S/W ONLY"
instead of the double sigma.
could occasionally result in multiplication errors; defective parts that Intel caught were marked with
"16 BIT S/W ONLY" instead of the double sigma.
The only other information I have about revision levels comes from a March 30, 1987 document titled
"**80386-C0 STEPPING INFORMATION**":
@ -101,7 +101,9 @@ The only other information I have about revision levels comes from a March 30, 1
80386-C0 component identifier readable in DH after reset: 03H
80386-C0 revision identifier readable in DL after reset: 04H
However, the document does not indicate how a 80386-C0 part was marked.
However, that document does not indicate how a 80386-C0 part was marked, and I've found very little other
information on the C0 stepping; it may have been quickly superseded by the D0 stepping, which used revision
identifier 0x05.
### Errata
@ -164,8 +166,60 @@ plus the two errata from April 30 (#18 and #19), along with the following new er
This brought the total number of 80386-B1 errata to 21.
There was also a manufacturing problem that caused 32-bit multiplications to fail on some parts, which Intel
publicly acknowledged in September 1987. The problem affected the B1 stepping; it's unknown whether other
steppings were affected as well.
publicly acknowledged in April 1987.
From the San Jose Mercury News, April 11, 1987:
INTEL DISCOVERS A BUG IN ITS NEW 80386 CHIP
Author(s): CHRISTOPHER H. SCHMITT AND JIM BARTIMO, Mercury News
Business Writers Date: April 11, 1987 Section: Business
Intel acknowledged Friday that a bug has cropped up in its new flagship microprocessor chip.
Microprocessors serve as the electronic brains of devices ranging from personal computers to
home appliances.
Intel said the bug in its 80386 microprocessor produces incorrect answers when the chip
performs certain mathematical operations. "When you multiply one 32-bit number by another
32-bit number, you get the error," said Intel spokesman Jim Jarrett. A 32-bit number is one
that utilizes the full data path of the chip.
However, operating system software that would let the chip fully use its 32-bit characteristics
is still being developed, so the problem shouldn't immediately affect personal computer users.
Microsoft Corp. of Redmond, Wash., has announced its intention to deliver in early 1988 a 32-bit
operating system known as OS/2.
Even when using the 32-bit capabilities of the chip, the possibility of an error is "rare,"
Jarrett said.
Spokesman Bruce LeBoss said not all of the 100,000 80386 chips Intel has produced so far are
affected, but he declined to elaborate. Intel is sticking with a previously announced estimate
that it will sell from 500,000 to 1 million 80386s this year.
To address the problem, Intel said it is notifying computer companies and other customers and
extending the chip's warranty from one to two years. Anticipating that it will replace some
80386s already in the field, the company charged off an undisclosed amount to cover the
expense. One analyst estimated the charge at about $7 million.
Intel will test the chips it has already sold to determine which ones have the bug. But it will
not replace the chips for free. Instead, Intel will work with customers on an upgrade program.
Intel said it will be up to individual computer makers to work with consumers who have
purchased machines using the 80386 chip.
The problem may be most acutely felt by Houston-based Compaq Computer, which so far has
been the biggest producer of 80386-based computers. Compaq said it will disclose by early
next week plans for coping with the possibility that versions of its Deskpro 386 computer model
contain flawed chips.
The bug may cause some shortages of the 80386. The problem won't be fixed until July, so the
only guaranteed chips are those that have already been produced and have passed Intel's test.
"Everybody wants perfect chips and we'll have fewer of those to go around for a while," Jarrett
said. Analysts indicated that in the long run, the bug is more likely to be embarrassing than
anything else. "You have a complex chip here," said Daniel Klesken, an analyst for Montgomery
Securities in San Francisco. "One should not be surprised that (problems) happen occasionally."
The problem affected the B1 stepping; it's unknown whether other steppings were affected as well.
What follows is some additional information about early 80386 processors from various online sources.