Block Diagram
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3-13
3
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Counter 2 provides the tone for the speaker output function on the
PIB controller (the
SPEAKER_OUT
signal which can be cabled to an
external speaker via the remote reset connector).
The interval timers use the OSC clock input as their clock source. The
MVME2603/2604 drives the OSC pin with a 14.31818 MHz clock source.
16-Bit Timers
Four 16-bit timers are available on the MVME2603/2604. The PIB
controller supplies one 16-bit timer; the Z8536 CIO device provides the
other three. For information on programming these timers, refer to the data
sheets for the W83C553 PIB controller and the Z8536 CIO device, as
listed in
Appendix D, Related Documentation
.
Serial Communications Interface
The MVME2603/2604 uses a Zilog Z85230 ESCC (Enhanced Serial
Communications Controller) to implement the two serial communications
interfaces, which are routed through P2. The Z85230 supports
synchronous (SDLC/HDLC) and asynchronous protocols. The
MVME2603/2604 hardware supports asynchronous serial baud rates of
110B/s to 38.4KB/s.
Each interface supports the CTS, DCD, RTS, and DTR control signals as
well as the TxD and RxD transmit/receive data signals, and TxC/RxC
synchronous clock signals. Since not all modem control lines are available
in the Z85230, a Z8536 CIO is used to provide the missing modem lines.
A PAL device performs decoding of register accesses and pseudo interrupt
acknowledge cycles for the Z85230 and the Z8536 in ISA I/O space. The
PIB controller supplies DMA support for the Z85230.
The Z85230 receives a 10MHz clock input. The Z85230 supplies an
interrupt vector during pseudo interrupt acknowledge cycles. The vector is
modified within the Z85230 according to the interrupt source. Interrupt
request levels are programmed via the PIB controller. Refer to the Z85230
data sheet and to the MVME2603/ MVME2604 Programmer’s Reference
Guide, both listed in
Appendix D, Related Documentation
, for further
information.