NEAT chipset

The NEAT chipset is a
4 chip VLSI implementation of the control logic used in the IBM PC compatible PC/AT computers. It consists of the 82C211 CPU/Bus controller, 82C212 Page/Interleave and EMS Memory controller, 82C215 Data/Address buffer, and 82C206 Integrated Peripherals Controller. NEAT, official designation CS8221, was developed by Chips and Technologies.

History

The NEAT chipset descended from the first chipset that C&T had developed for IBM XT-compatible systems, which is based around the 82C100 "XT controller" chip. 82C100 incorporates the functionality of what had been, until its invention, discrete TTL chips on the XT's mainboard, namely:

8284 clock generator
8288 bus controller
8254 Programmable Interval Timer
8255 parallel I/O interface
8259 Programmable Interrupt Controller
8237 DMA controller
8255 Programmable Peripheral Interface
DRAM/SRAM controller
XT Keyboard controller

IBM PC compatibility is provided by C&T's 82C206 Integrated Peripheral Controller, introduced by C&T in 1986. This chip, like its predecessor the 82C100, provides equivalent functionality to the TTL chips on the PC/AT's mainboard, namely:

82284 clock generator
82288 bus controller
8254 Programmable Interval Timer
two 8259 Programmable Interrupt Controllers
two 8237 DMA controllers
74LS612 Memory Mapper chip
MC146818 NVRAM/RTC chip

NEAT CS8221's predecessor, called CS8220, requires five chips for a virtually complete motherboard, while NEAT requires four, and added support for separate ISA bus clocks. The eventual successor to the NEAT chipset, 82C235 Single Chip AT, amalgamates all of the chips of the NEAT chipset into a single chip.

Other manufacturers

Other manufacturers produced equivalent chips. OPTi, for example, produced a two-chip "AT controller" chipset comprising the OPTi 82C206 and 82C495XLC, which is found in many early 80486 and Pentium AT-compatible machines. The OPTi 82C206 is pin and function compatible with C&T's 82C206. The 82C495XLC incorporates the additional memory controller and shadow RAM support.