Introduction - North Star ZPB-A Manual

INTRODUCTION
The North Star Computers Z80A Processor Board (ZPB) provides Z80
microprocessor capability on the S-100 bus. The use of the Z80A
chip allows full speed 4MHz operation as a standard feature. The
ZPB can be used in any standard S-100 bus computer and will
operate in conjunction with nearly all other S-100 bus boards.
However, the ZPB has been specifically designed to integrate into
the North Star Computers HORIZON computer system. In addition to
the Z80A microprocessor and support logic to interface to the
standard S-100 bus, the ZPB contains the following features and
options:
1. AUTO-JUMP feature that will 'cause an automatic jump to any
address at power-on or reset.
2. VECTORED INTERRUPTS. ZPB logic will respond to eight levels
of interrupt requests, determine the highest priority request
pending and generate the appropriate RST instruction. The
logic may be disabled to allow the function to be performed on
another board.
3. FRONT PANEL INTERFACE for direct connection to IMSAI and other
similar front panels.
4. ADDRESS MIRROR feature to simulate the input/output
characteristics of the 8080 microprocessor. This feature
maintains compatibility with some S-100 bus peripheral boards.
Address mirroring may be disabled to allow use of the more
powerful Z80 protocol.
5. PROM OPTION. lK of 2708 type erasable PROM can be added to
the ZPB. This allows configuration of systems that requ~re
resident monitor and bootstrap programs.
If you have purchased t~e ZPB as a kit, first skim this entire
manual. Before beginning assembly, carefully read the Assembly
Information section.
Whether you purchased the ZPB as a kit or assembled, read the
Configuration section before attempting to use the ZPB. Note
that a Z80 Technical Manual has been included to fully describe
the operation of the Z80A.
3
North Star Z80A PROCESSOR BOARD