INTRODUCTION
The MC68HC901 Multi-Function Peripheral (MFP) is a member of the M68000 Family of peripherals. Unless otherwise specified, the MC68HC901 multi-function peripheral is hereafter referred to as the MFP in this document. Many features of the MFP make reference to the MC68000 Family of 16- and 32-bit microprocessors, which includes the MC68HC000, MC68HC001, and the MC68EC000. These microprocessors are referred to as the MC68000 within this document.
The MFP directly interfaces to the MC68000 via the asynchronous bus structure. Both vectored and polled interrupt schemes are supported with the MFP providing unique vector number generation for each of its 16 interrupt sources. Additionally, handshake lines are provided to facilitate direct memory access controller (DMAC) interfacing. Refer to Figure 1-1 for a block diagram of the MFP.

KEY FEATURES
The MFP performs many of the functions common to most microprocessor-based systems.
The resources available to the user include:
• Eight individually programmable I/O pins with interrupt capability
• 16-source interrupt controller with individual source enable and masking
• Four timers, two of which are multi-mode timers
• Single-channel full-duplex universal synchronous/asynchronous receiver-transmitter(USART) which supports:
  — asynchronous formats
  — byte synchronous formats, with the addition of a polynomial generator checker
By incorporating multiple functions within the MFP, the system designer retains flexibility while minimizing device count.