NEAT chipset
The NEAT chipset (the acronym standing for "New Enhanced AT") is a 4 chip VLSI implementation (including the 82C206 IPC) 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 (IPC). NEAT, official designation CS8221, was developed by Chips and Technologies.[1]
History
[edit]The NEAT chipset descended from the first chipset that C&T had developed for IBM XT-compatible systems, which is based around the 82C100[2] "XT controller" chip. 82C100 incorporates the functionality of what had been, until its invention, discrete TTL chips on the XT's mainboard, namely:[3]
- 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 (PPI)
- DRAM/SRAM controller
- XT Keyboard controller
IBM PC compatibility is provided by C&T's 82C206 Integrated Peripheral Controller (IPC), 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:[1]
- 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[4] (buffers and memory controllers) for a virtually complete motherboard, while NEAT requires four, and added support for separate ISA bus clocks.[5] The eventual successor to the NEAT chipset, 82C235 Single Chip AT (SCAT), amalgamates all of the chips of the NEAT chipset into a single chip.[6]
Other manufacturers
[edit]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.[3]
References
[edit]- ^ a b Scott Mueller (2003). Upgrading and Repairing PCs. Que Publishing. pp. 230. ISBN 9780789729743.
- ^ 82C100 PS/2 Model 30 and Super XT" Compatible Chip, Datasheet
- ^ a b Michael H. Tooley (2005). PC Based Instrumentation and Control. Elsevier. p. 32. ISBN 9780750647168.
- ^ CS8220 PC/AT compatible CHIPSet, Datasheet
- ^ Chips and Technologies Short Form Catalog 1989
- ^ 82C235 Single Chip AT (SCAT), Datasheet