Download MPA Multi-Protocol Terminal Emulation Adapter Using the DP8344

5.0 Hardware Architecture: discusses the MPA-II hardware architecture including a description of the BCP core,
PC interface, Front-end interface, and miscellaneous support circuitry.
ALEC emulation card interface modes, including SIMPC
MASTERTM by SIMWARE, RELAY GoldÉ by RELAY Communications, and CrossTalkTM MK.4 by Digital Communications Associates, can be used with the MPA-II.
6.0 Software Architecture: discusses the Kernel, coax
task, twinax task, and interrupt structure.
Included in this chapter is an in depth discussion of the
IRMATM , IBM and Smart Alec TM interfaces.
7.0 Loader and MPA-II Diagnostics: discusses soft-loading the BCP, configuring the MPA-II interface mode, and the
diagnostics provided for testing the MPA-II hardware.
Appendix A. Hardware Reference: provides the complete
MPA-II schematic, assembly drawing, board layout and PAL
equations.
Appendix B. Timing Analysis: discusses the timing of the
MPA-II system.
Appendix C. Filter Equations for the Combined Coax/
Twisted Pair Interface: provides the derivation of the filter
equations for the combined coax/twisted pair interface.
Appendix D. References: is a list of reference materials
and company contacts.
DP8344B BCP
The DP8344B BCP is a communications processor designed to efficiently process IBM 3270, 3299 and 5250 communications protocols. A general purpose 8-bit protocol is
also supported.
The BCP integrates a 20 MHz, 8-bit, Harvard architecture,
RISC processor and an intelligent, software-configurable
transceiver on the same low power microCMOS chip. The
transceiver is capable of operating without significant processor interaction, releasing processor power for other tasks.
Fast, flexible interrupt and subroutine capabilities with onchip stacks make the power readily available.
The transceiver is mapped into the processor’s register
space, communicating with the processor via an asynchronous interface which enables both sections of the chip to
run from different clock sources. The transmitter and receiver run at the same basic clock frequency although the receiver extracts a clock from the incoming data stream to
ensure timing accuracy.
The BCP is designed to stand alone and is capable of implementing a complete communications interface, using the
processor’s spare power to control the complete system.
Alternatively, the BCP can be interfaced to another processor with an on-chip interface controller arbitrating access to
data memory. Access to program memory is also possible,
providing the ability to softload BCP code. The MPA-II implements these features.
A simple line interface connects the BCP to the communications line. The receiver includes an on-chip analog comparator suitable for use in a transformer-coupled environment,
although a TTL-level serial input is also provided for applications where an external comparator is preferred.
A typical system is shown in Figure 1-1. Both coax and twinax line interfaces are shown, as well as an example of the
(optional) remote processor interface.
For a detailed discussion on the BCP refer to the DP8344B
Biphase Communications Processor data sheet.
MPA-II Description
The Multi-Protocol Adapter II (MPA-II) is a complete design
solution for IBM 3270, 3299, and 5250 connectivity products. The MPA-II system is intended to be a design example
for customers to use in developing their own products using
the Biphase Communications Processor, BCP. The BCP is a
‘‘system on a chip’’ designed by National Semiconductor to
specifically address the IBM connectivity market place. Built
on the tradition of the DP8340/41 3270 receiver/transmitter
pair, the BCP takes the state of the art in IBM communications a step further. The MPA-II provides the system support
hardware and complete link level firmware to achieve 3270/
3299 CUT, DFT, and 5250 emulation with the BCP and an
appropriate PC emulator. The MPA-II Design/Evaluation Kit
does not include the PC emulation software. Thus, the end
user must purchase the PC emulation software to bring up a
live terminal emulation session using the MPA-II. PC emulation software such as DCA’s E78 for MPA-II IRMA mode,
one of IBM’s PC 3270 emulation programs for MPA-II IBM
mode, DCA’s EMU for MPA-II ALEC mode, or any of the
third party vendors which support either the IRMA, IBM or
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