UPI-452

The Intel UPI-452 (Universal Peripheral Interface) is a 68 pin CHMOS Slave I/O Processor with a sophisticated
bi-directional FIFO buffer interface on the slave bus and a two channel DMA processor on-chip. The UPI-452
is the newest member of Intel's UPI family of products. It is a general-purpose slave I/O Processor that allows
the designer to grow a customized interface solution.

The UPI-452 contains a complete 80C51 with twice the on-chip data and program memory. The sophisticated
slave FIFO module acts as a buffer between the UPI-452 internal CPU and the external host CPU. To both the
external host and the internal CPU, the FIFO module looks like a bi-directional bottomless buffer that can both
read and write data. The FIFO manages the transfer of data independent of the UPI-452 core CPU and generates an interrupt or DMA request to either CPU, host or internal, as a FIFO service request.

The FIFO consists of two channels:the Input FIFO and the Output FIFO. The division of the FIFO module
array, 128 bytes, between Input channel and Output channel is programmable by the user. Each FIFO byte
has an additional logical ninth bit to distinguish between a data byte and a Data Stream Command byte.

Additionally, Immediate Commands allow direct, interrupt driven, bi-directional communication between the
UPI-452 internal CPU and external host CPU, bypassing the FIFO.

The on-chip DMA processor allows high speed data transfers from one writeable memory space to another.
As many as 64K bytes can be transferred in a single DMA operation. Three distinct memory spaces may be
used in DMA operations; Internal Data Memory, External Data Memory, and the Special Function Registers (including the FIFO IN, FIFO OUT, and Serial Channel Special Functions Registers).