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**Intro:
The information  contained within this  file should not  be considered
100%  correct.   Where  possible   information  has  been  taken  from
datasheets, however  even this info  may be incorrect.  The datasheets
state what  the chip should  do, not what  they actually do.  This is,
compounded further by different revisions of chips.

This  document will  never be  complete, and  I have  no intention  of
finding every  datasheet for  every chip  set. Some  of the  chip sets
listed are  from later systems  in the PIII/P4/Athlon era.   There are
many websites  with information on  these chip sets and  these entries
will likely not be expanded upon.  The focus of this document is early
PC/XT to  Pentium chip sets.  There are  few sites that  clearly illu-
strate this information, and how they relate to each other.

I  aim  to  prioritize   cataloging  significant,  rare  or  otherwise
interesting chip sets.

BTW the reason I wrote all of this down, is so that I could FORGET it.
Basically I needed to free  up some RAM.  I've  a head full  of arcane
snippets of  information on this subject.   I don't want to  end up  a
crazy old man  ranting random disjointed information  ("The C&T CS8220
came before the CS8221 you KNOW!") to disinterested passersby,  unable
to see how senile I've become. A side benefit, this might be useful to
someone else:-)

**Quote style:...
**Cant find a chip?
Early chip sets have  a title and a part no. to refer  to the chip set
as a  whole. As time went  on the chip  set became one chip,  so later
chip sets are usually referred to by  the part no. on the actual chip.
These are  usually called "Single  Chip" by the  manufacture, although
they nearly  always follow the 2-chip  North/South-bridge paradigm. So
these are referred to by for example, "M1521/M1523" or "M1521/M23" for
short. If there is a part number for  the chip set as a whole that has
precedence. Try the search function for  a chip part no. and hopefully
it will turn up the chip set it was part of.

**Why this document is not GPL or a wiki...
**Definition of a chip set:...
**'chip set', 'chip-set' or 'chipset'?...
**What's not included:...
**Who made the first chip set?...
**Spelling errors/mistyped words...
**Info needed on:...
**A note on VESA support of 486 chipsets....
**Datasheets:...
*_IBM...
*ACC Micro...
*ALD...
*ALi...
*AMD . . . . . . . [no datasheets, some info]...
*Chips & Technologies...
*Contaq  . . . . . [no datasheets, some info]...
*Efar Microsystems [no datasheets, some info]...
*ETEQ...
*Faraday...
*Forex . . . . . . [List only, no datasheets found]...
*Intel...
**82485       Turbo Cache (and 485Turbocache)                      c90
***Notes:...
***Info:...
***Versions:...
***Features:...
**82489DX       Advanced Programmable Interrupt Controller    10/12/92...
**82495DX/490DX DX CPU-Cache Chip Set                           <Sep91...
**82495XP/490XP Cache Controller / Cache RAM (for i860)       06/05/91...
**82496/491     Cache Controller / Cache RAM (for P5 Pentium) 03/22/93...
**82497/492   Cache Controller / Cache RAM (for P54 Pentium)    <Nov94...
**82498/493   Cache Controller / Cache RAM (for P54 Pentium)    <Nov94...
**
**Later chipsets (basic spec):
**440 series:...
**450NX  (?)            06/29/98:...
**?????  (Profusion)    c:99...
**800 series...
*Headland/G2...
**HT25          3-volt Core Logic for 386SX                    c:Dec92
***Info:
The HT25  is the industry’s first  3-Volt single chip  core logic with
integrated  power management  for  386SX based  3-Volt systems.   Pro-
grammable  power  management features  give  system manufacturers  the
flexibility of offering customized system solutions.

GENERAL DESCRIPTION
The HT25 is a  PC/AT1M compatible single-chip solution with integrated
power management  designed to operate in a  3-Volt system environment.
This highly integrated chip facilitates  the design of low power, high
performance portable systems.  The  HT25 supports 3-Volt 386SX CPUs at
clock  speeds  up  to  25MHz  at  2.7V to  3.6V.   It  supports  power
management functions using the System Management Mode (SMM).

Flexible  power  management is  the  cornerstone  of the  HT25.   This
approach provides  power saving  features that  can be  customized for
product  differentiation.  Power  management  features include  system
activity monitors  and general purpose  I/O pins.  The  HT25 generates
System Management  Interrupt (SMI) to process  activity information or
when access  to powered down  peripherals is detected.   Further power
savings are achieved through the HT25’s ability to control CPU and NPU
clocks and support for slow refresh and self refresh DRAMs.

The HT25 Memory Controller features BIOS Shadowing, Memory Relocation,
EMS, Page  Mode Memory Access and Interleaving.  The memory controller
allows memory banks to be reordered to allow more efficient memory in-
terleaving. The HT25 supports 512Kb, le, and 4Mb DRAMs.

The HT25 architecture  is optimized for 3-Volt system  designs, the SD
bus acknowledge input provides a flexible I/O bus architecture and the
XD bus is buffered directly  from the HT25.  Further, no external data
bus buffers are required for a closed 3V system.

***Configurations:...
***Features:...
**HT35          Single-Chip Peripheral Controller [partial info]     ?...
**HTK320        386DX Chip Set                                 c:Sep91...
**HTK340        "Shasta" 486 Chip Set                          c:Jun92...
**Support Chips:
**HT44          Secondary Cache                                c:Jun92...
**Other:...
*HMC (Hulon Microelectronics)...
*Logicstar...
*Motorola...
*OPTi...
*PC CHIPS/Amptron/Atrend/ECS/Elpina/etc...
*SIS...
*Symphony...
*TI (Texas Instruments)...
*UMC...
*Unresearched:...
*VIA...
*VLSI...
*Western Digital...
*Winbond...
*ZyMOS...
*General Sources:...