NEAT chipset

Motherboard with NEAT chipset for the Intel 80286

The NEAT chipset (the acronym standing for "New Enhanced AT") was a 3-chip chipset for IBM PC compatible computers. It was developed by Chips and Technologies.^[1]

History

The NEAT chipset descended from the chipset that C&T had developed for IBM XT-compatible systems, which was based around the 82C100 "XT controller" chip. This chip incorporated the functionality of what had been, until its invention, discrete TTL chips on the XT's mainboard, namely:^[2]

• the 8284 clock generator^[2]
• the 8288 bus controller^[2]
• the 8254 Programmable Interval Timer^[2]
• the 8255 parallel I/O interface^[2]
• the 8259 Programmable Interrupt Controller^[2]
• the 8237 DMA controller^[2]

The central chip of the NEAT chipset was C&T's 82C206 chip, introduced by C&T in 1986. This chip, like its predecessor the 82C100, provided equivalent functionality to the TTL chips on the PC/AT's mainboard, namely:^[1]

• the 82284 clock generator^[1]
• the 82288 bus controller^[1]
• the 8254 Programmable Interval Timer^[1]
• the two 8259 Programmable Interrupt Controllers^[1]
• the two 8237 DMA controllers^[1]
• the MC146818 NVRAM/RTC chip^[1]

This set of components comprised most of the logic (aside from the CPU itself) on a PC/AT-compatible mainboard, and the creation of the 82C206 allowed mainboard manufacturers to significantly reduce the number of components on, and thereby the cost of manufacture of, such mainboards. However, mainboards still required four other chips, in addition to the 82C206. These other chips were buffers and memory controllers. In concert, these five chips were C&T's CS8220 chipset.^[1]

The NEAT chipset was the successor to the CS8220. It was officially designated the CS8221. It required only three extra chips in addition to the 82C206.^[1]

The successor to the NEAT chipset was the SCAT chipset, which amalgamated all of the chips of the NEAT chipset into a single chip, the 82C836.^[1]

Other manufacturers

Other manufacturers produced equivalent chips. OPTi, for example, produced a two-chip "AT controller" chipset comprising the OPTi 82C206 and 82C495XLC, which was found in many early 80486 and Pentium AT-compatible machines. The OPTi 82C206 provided equivalent functionality to:^[2]

• a 8254 Programmable Interval Timer^[2]
• two 8259 Programmable Interrupt Controllers^[2]
• two 82437 DMA controllers^[2]
• a MC146818 NVRAM/RTC chip^[2]
• a 74LS612 Memory Mapper chip^[2]

The 82C495XLC incorporated the additional memory controller and shadow RAM support.^[2]

References

1. ^ ^{a b c d e f g h i j k} Scott Mueller (2003). Upgrading and Repairing PCs. Que Publishing. pp. 230. ISBN 0789729741. 
2. ^ ^{a b c d e f g h i j k l m n} Michael H. Tooley (2005). PC Based Instrumentation and Control. Elsevier. pp. 32. ISBN 0750647167.