Overview
The HD64570 serial communications adaptor (SCA) converts parallel data to serial data for communication with other devices. Its two independent, full-duplex transceivers support both synchronous (bit-synchronous or byte-synchronous) and asynchronous communication. Extensive protocol functions are provided.
The SCA chip provides FIFO transmit and receive buffers with 32 stages each and a four-channel direct memory access controller (DMAC) with chained-block transfer facilities, enabling high speed transfer of data between SCA and memory. A built-in bus arbiter and 16-bit bus interface support high-performance system designs.

Features
• Data transfer rate: 50 bits/s to 7.1 Mbits/s (f = 10 MHz),
   50 bits/s to 12 Mbits/s (f = 16.7 MHz)
   50 bits/s to 5.7 Mbits/s (f = 8 MHz)*
• Protocol support
   _ Asynchronous (ASYNC): 5 to 8 bits + parity
   _ Byte synchronous (COP): bisync, X.21, DDCMP, etc.
   _ Bit synchronous (BOP): frame relay, HDLC, SDLC, X.25 link level (LAPB), LAPD etc.
• Highly efficient data transfer: two 32-byte FIFOs (transmit/receive) per channel
• Error detection: parity (asynchronous)
   CRC-16, CRC-CCITT (byte- and bit-synchronous)
      ™SDLC is a trademark of International Business Machine.
   Transmission codes: NRZ, NRZI, FM0, FM1, Manchester
   Operating modes: normal operating mode (full-duplex), auto echo, local loop back
   DMA transfer: on-chip DMAC with four channels and chained-block transfer capability
   Address space: 16 Mbytes
   Bus interface: connects to 64180-, 8086-, and 68000-system 8-/16-bit MPU buses
   Timers: time-out detection, etc.
   Power supply: 5 V ± 10% (−20 to 75°C) for 10-MHz chip,
                  5 V ± 5% (0 to 70°C) for 16.7-MHz chip
                  5 V ± 10% (−40 to 85°C) for 8-MHz chip*