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Hardware
The FLT-68K is based around the popular Motorola MC68000 microprocessor with its 16-bit data bus
and 24-bit address bus. The system also incorporates a range of peripheral devices and is driven by a
10MHz clock.
The FLT-68K is supplied with 16K bytes of RAM, which is more than sufficient for most teaching
requirements, but is expandable to a total of 512K bytes making it also suitable for larger scale
applications. Two RAM memory sockets accept 6264 8K, 62256 32K, or 551001 128K static RAMs in
pairs resulting in 16K, 64K and 256K bytes respectively. Two further auxiliary RAM sockets may also
be used to accommodate these same devices resulting in a maximum RAM size of 512K bytes.
Also as standard, two 27256 32K EPROMs are fitted containing the FLT-68K's monitor firmware. These
firmware routines may be replaced by, or incorporated into, the user's own firmware for turnkey
applications. Also, two 27512 64K EPROMs may be used to expand the ROM memory to 128K bytes in
total.
The MC68681 Dual Universal Asynchronous Receiver/Transmitter (DUART) provides two RS232
compatible serial ports, one for connection with a data terminal or host computer such as an IBM
compatible PC, and the other for connection to a printer or for use by the user. Two male 9-way D-
type connectors are provided.
The MC68230 Peripheral Interface/Timer (PI/T) provides 24 parallel input/output lines plus a
counter/timer. Access to these lines is by way of a 40-pin IDC header which is compatible with a range
of development and educational peripherals such as our applications board, switch and lamp board,
and 4mm interface module.
Further user expansion may be gained by way of the male 64 way DIN41612 connector, which
provides access to all the MC68000 processor signals.
An on-board system reset switch is provided, as are status LEDs, and fault switches which allow the
simulation of hardware faults for student fault-finding exercises.
Firmware A 64K byte firmware package is provided with the FLT-68K making the board a mini
development system. It comprises a comprehensive monitor, a line-by-line assembler and a
disassembler.
The monitor program has been made as simple as possible to use, with each of the 53 different
commands available being invoked by simple two-letter codes. No further information has to be
remembered as any additional parameters are requested by the monitor in a clear and verbose manner
where required. The occasional user will benefit from the in-built help option which provides a brief
description of each of the monitor commands. In most cases it will not be necessary to refer to the
user's manual, once the detailed description of the commands has been studied.
The line-by-line assembler enables 68000 assembler language programs to be entered and assembled
a line at a time making program entry simple and quick. For test and demonstration programs this
method will be found faster and more convenient than using full cross-software facilities on a host
computer.
68000 machine code anywhere in memory may also be disassembled with the resulting assembler
source code being displayed on screen or printed out if a printer is connected. Other monitor
commands allow code to be executed and single-stepped, allow breakpoints to be set, registers and
memory contents to be displayed, and much more.
Demonstration routines for use with the Applications Board, and test programs to ensure the FLT-68K
board is fully functional are also incorporated into the firmware.
Documentation
No matter how good a microprocessor board may be, for the user to be able to become familiar with it
as quickly as possible and use it to its full potential it is vital that it is matched by equally good quality
documentation. Consequently, much effort was given to ensuring that the user's manual supplied with
the FLT-68K gives the user the best possible start. Not only is every aspect of the system described,
but diagrams and example programs are given where possible.
The documentation leads the user through setting up the system and provides detailed information on
its hardware and firmware. Monitor commands are described in detail, as are monitor system calls and
the 68000 instruction set and addressing modes. The use of the MC68681 Dual Universal
Asynchronous Receiver/Transmitter (DUART) and MC68230 Peripheral Interface/Timer (PI/T) is also
described with examples, and full schematics are provided for the board.
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