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CHAPTER 3.
PROGRAMMING INFORMATION
3-1.
INTRODUCTION
The Intel iSBC 86/14/30 Single board computer contains several
programmable devices, including an 8255A Programmable Peripheral
Interface, an 825lA Programmable Communications Interface (PCI), an
8253-5 Programmable Interrupt Timer, and an 8259A Programmable Interrupt
Controller.
This chapter provides the necessary programming information
for the devices and provides typical programming examples for each.
Memory and I/O port addresses are provided in table form.
3-2.
MEMORY ADDRESSING
The addresses used by the local CPU in accessing the EPROM and the dual
port RAM are referred to in the text as local addresses, and those used
by the Multibus devices in accessing the dual port
RAM
are referred to as
Multibus addresses (of dual port
RAM).
The relationship between the
addresses is listed in Tables 3-1 and 3-2 and described in the text.
The iSBC 86/14/30 board provides you with the ability to relocate the
on-board
RAM
and EPROM to anyone of 16 megabytes of system memory, with
some limitations.
In order for the dual port
RAM
to be accessible by
both a local and an off-board processor, the dual port
RAM
must be placed
into Multibus addresses ranging between xFOOOOH and x3FFFFH (86/30 with
maximum EPROM and
RAM)
or between xFOOOOH and xOFFFFH (86/14 with maximum
EPROM and
RAM).
3-3.
iSBC 86/14 BOARD MEMORY ADDRESSING
As shipped, the iSBC 86/14 board accommodates up to 32k bytes of
RAM
and
up to 64k bytes of EPROM.
By installing an iSBC 300A
RAM
Expansion
Multimodule Board, the on-board
RAM
capacity can be doubled.
Table 3-1A
provides the memory address ranges for various EPROM and
RAM
configurations of the iSBC 86/14 board, including a configuration with
the iSBC 300A
RAM
Expansion Multimodule Board.
Table 3-lA shows that the Multibus address range for accessing EPROM is
from xFOOOOH to xFFFFFH and the local address always ends with the
highest possible address (xFFFFFH) regardless of the size of the memory.
The factory default condition is for installation of four 2716 devices
providing memory from xFEOOOH through xFFFFFH.
3-1
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