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AMPRO COMPUTERS, INC. APPLICATION NOTE
--------------------------------------
Number: #AAN-8802 Date: Jan 19, 1988 Author: R. Lehrbaum
Title: An Introduction to the AMPRO Little Boards
Product(s): Little Board/PC, Little Board/186, Little Board/Z80
Abstract: An overview of the AMPRO Little Board architecture, including a
brief description of each Little Board single board computer, and
a comparison among the various Little Boards.
-------------------------------------------------------------------------------
WHAT IS A LITTLE BOARD?
-----------------------
AMPRO has created the "Little Board" (TM) family of single board computers
(SBCs) to provide engineers with an alternative to backplane based
microcomputer board products. Each Little Board SBC incorporates all of the
components of a complete microcomputer system on a single compact circuit
assembly. A Little Board can often replace four or five ordinary
microcomputer boards in a backplane architecture.
The Little Board SBCs are ideal for embedded microcomputer applications in
which the SBC is buried within an instrument, machine, controller, or other
device. Some typical applications for the Little Boards are: data
acquisition and control, portable instruments, protocol conversion, machine
control, data logging, intelligent terminals, communications controllers,
security systems, diskless workstations, remote data logging, network servers,
distributed processing, and SCSI device control.
Why Use a Little Board?
AMPRO's Little Board SBC's have been designed using the most highly integrated
IC's available in the industry. They are compact (45 sq.inches), low power (4
to 7 watts), cost effective, and extremely reliable. In addition, each Little
Board is supported with a rich set of BIOS and operating system software,
targeted to commercial and industrial embedded applications.
Included on each Little Board SBC is a microprocessor, bootstrap or BIOS ROM,
system memory, and a full set of I/O interfaces (serial ports, printer port,
and mass storage interfaces). In many applications, all the electronics
required is located directly on the Little Board; in most other cases, a
single additional application specific interface (e.g. an A-to-D converter) is
added externally by the system designer.
Using an AMPRO Little Board SBC instead of a set of boards plugged into a
backplane reduces cost, saves space and power, increases overall system
reliability, and simplifies system packaging. Employing a Little Board as a
ready-to-use component rather than designing a custom microcomputer board
results in a substantial saving in development costs, time, and risks.
Industry Standard SCSI Bus
Each AMPRO Little Board includes an industry standard Small Computer System
Interface (SCSI) bus. The SCSI bus allows simple ribbon cable connection of a
wide variety of external peripherals such as hard disk, tape, scanners,
optical disks, RAM disks, printers, and LAN's. Also, the AMPRO "SCSI/IOP",
can be used to connect data acquisition and control I/O cards to any Little
Board SBC via SCSI.
If the Little Board's SCSI interface is not needed for connection to standard
SCSI devices, the board's SCSI port can be used as a simple digital I/O port.
At least one manufacturer offers a line of low cost data acquisition and
control interfaces (A-to-D, digital I/O, relays, opto-isolated inputs, etc.)
which can be connected to any Little Board in this manner.
Little Board Form Factor
All Little Board SBCs match the footprint, mounting hole pattern, and power
connections of industry standard 5-1/4" disk drives. This form factor (5.75"
by 8") makes floppy or hard disk-based system integration easy and efficient,
since the dimensions of the SBCs and mass storage devices match.
CHOOSING THE RIGHT LITTLE BOARD FOR THE JOB
-------------------------------------------
The three AMPRO Little Boards -- Little Board/PC, Little Board/186, and Little
Board/Z80 -- offer a range of processing power, onboard memory, standard I/O
interface resources, and expansion capabilities. Table 1 summarizes the
features of all three Little Board SBCs. The two-board set consisting of the
Little Board/186 and Expansion/186 multi-function daughter card is also
included. The following paragraphs summarize some of the unique features and
advantages of each of the three AMPRO Little Board SBCs.
Little Board/PC
The Little Board/PC is a highly expandable and flexible SBC which combines the
advantages of CMOS, small size, high integration of functionality, and IBM PC
compatibility on a single compact board. The Little Board/PC is essentially a
complete "Turbo" PC/XT on a single 5.75 x 8" pc board. Its performance, is
half way between a standard IBM PC/XT and PC-AT.
The Little Board/PC can be substituted for an IBM PC in virtually any
application. Its onboard hardware and ROM-BIOS are PC compatible, and PC-DOS
(version 3.x) is normally used as the board's operating system. In addition,
the Little Board/PC is easily expanded via standard off-the-shelf IBM PC add-
on cards, since a standard PC expansion bus header is included on the board.
The AMPRO StackPlane/PC expansion adapter even allows IBM PC expansion boards
to be integrated directly into the Little Board form factor!
The IBM PC has found its way into a seemingly limitless number of industrial
and commercial applications. All of these -- including office, factory, and
consumer applications -- are equally well suited to implementation on the
Little Board/PC. The AMPRO Solid State Disk (SSD) support utilities make it
easy to convert a system from floppy-based to EPROM-based or nonvolatile RAM-
based operation (using onboard devices). This onboard SSD support greatly
enhances the Little Board/PC's suitability for embedded and dedicated
applications.
Summary: The main advantages of the Little Board/PC are its IBM PC
compatibility (hardware and software), its low power consumption, its very
high level of integration, its PC expansion bus, and its onboard solid state
disk drive option. Because of the board's IBM PC hardware and software
compatibility, you can develop and debug your application's hardware and
software on an IBM PC or AT, for operation on the Little Board/PC.
Little Board/186
The Little Board/186 was designed to offer the lowest possible component count
MS-DOS (PC-DOS) SBC. Both the 8 MHz and 16 MHz versions of the board provide
exceptional performance/cost ratios. (The Little Board/186 provides execution
speeds comparable to that of a PC-AT.) In addition to the board's onboard
resources, a number of expansion options are available from AMPRO and others:
o The board's SCSI bus interface can be used in a variety of ways: with
standard SCSI peripherals, as a digital I/O bus, or with several vendors'
low cost data acquisition and control adapters.
o The AMPRO Expansion/186 multi-function daughter board offers the options
of: 512K additional RAM, 2 serial ports, a battery backed clock, an I/O
bus, and an 8087 math coprocessor (8087 option not available with the 16
MHz Little Board/186).
o The AMPRO Project Board/186 daughter board offers a convenient means to
add custom circuitry or interfaces using wire-wrap.
o AMPRO's implementation of the Digital Research CDOS operating system for
the Little Board/186 (and Expansion/186) offers multi-tasking and multi-
user support (supports four physical, and twelve virtual consoles), and
allows direct access to hard disk partitions as large as 512 Megabytes!
IBM PC-DOS (version 3.x) is normally used as the Little Board/186's operating
system, and the board implements the standard 360K or 720K byte floppy
formats. However, unlike the Little Board/PC, the Little Board/186 is not
hardware-compatible with the IBM PC. (For example, the video and keyboard
functions are routed to one of the board's RS232C serial ports rather than to
the normal PC hardware.) Consequently, software that attempts to access IBM
PC hardware directly cannot be used without modification. This is not a
problem if you are writing the software yourself, since the board's ROM-BIOS
provides a measure of compatibility with the PC environment on a BIOS level
and supports the required PC-DOS (MS-DOS) functions. This issue is discussed
in detail in the board's technical manual.
Summary: The main advantages of the Little Board/186 are its excellent
performance/price ratio and its use of standard IBM PC-DOS (version 3.x) as
its operating system. The combination of the Little Board/186 and
Expansion/186 provides many of the most commonly required system functions in
a compact two-board package. Because the board provides a subset of IBM PC
ROM-BIOS functions and uses PC-DOS as its operating system, you can develop
and debug your application's software on an IBM PC or AT, for operation on the
Little Board/186.
Little Board/Z80
The Little Board/Z80 was designed to offer the world's simplest complete CP/M
based system. It is architecturally similar to the Little Board/186, but with
less CPU "horsepower", less RAM and EPROM space, and no DMA. Several
expansion options are available from AMPRO and others:
o The board's SCSI bus interface can be used in a variety of ways: with
standard SCSI peripherals, as a digital I/O bus, or with several vendors'
low cost data acquisition and control adapters.
o The AMPRO Project Board/Z80 daughter board offers a convenient means to
add custom circuitry or interfaces using wire-wrap.
Summary: The main advantage of the Little Board/Z80 is its low cost. The
Little Board/Z80 is ideal for applications which are not time-critical, and
which can be accomplished with the board's I/O interfaces and expansion
options. It comes complete with an enhanced CP/M operating system as well as
a rich set of utility software, including SCSI hard disk utilities. One
useful utility included with the board allows it to read and write IBM PC
diskettes. The Little Board/Z80 is also very low in component count, which
results in high system reliability.
Table 1. Comparison of AMPRO Little Board Features
----------------------------------------------------------------
Little Board/PC
----------------------------------------------------------------
CPU NEC V40
System clock rate 7.16 MHz
Memory data path 8 bits
Math coprocessor no
DMA yes
Battery backed clock plug-in module
Onboard RAM 256K/512K/768K
BIOS/bootstrap EPROM 1 64K socket
Spare memory sockets 2 (Note 1)
Serial ports 2
Parallel printer port yes
No. of floppy drives 2
Type of floppy drives 360K,720K,1.2M,1.4M
SCSI bus interface yes
Keyboard port yes
Speaker port yes
Video controller plug-in option
Expansion bus onboard PC BUS
Operating system PC-DOS 3.x
Software usable IBM PC compatable
Power consumption (typ) 4-5 watts
Performance (Norton SI) 2.5
----------------------------------------------------------------
Little Board/186 Little Board/186
+ Expansion/186
----------------------------------------------------------------
CPU Intel 80186 Intel 80186
System clock rate 8/16 MHz 8/16 MHz
Memory data path 16 bits 16 bits
Math coprocessor yes (8MHz only) no
DMA yes yes
Battery backed clock onboard option plug-in module
Onboard RAM 1 megabyte 512K
BIOS/bootstrap EPROM 2 64K sockets 2 64K sockets
Spare memory sockets no no
Serial ports 4 (Note 2) 2
Parallel printer port yes yes
No. of floppy drives 4 4
Type of floppy drives 360K,720K 360K,720K
SCSI bus interface yes yes
Keyboard port no (Note 3) no (Note 3)
Speaker port no no
Video controller no (Note 3) no (Note 3)
Expansion bus proprietary bus via SCSI (Note 4)
Operating system PC-DOS 3.x, CDOS PC-DOS 3.x, CDOS
Software usable MS-DOS "generic" MS-DOS "generic"
Power consumption (typ) 7-10 watts 7 watts
Performance (Norton SI) 4.2/8.4 (8/16MHz) 4.2/8.4 (8/16MHz)
----------------------------------------------------------------
Little Board/Z80
----------------------------------------------------------------
CPU Zilog Z80A
System clock rate 4 MHz
Memory data path 8 bits
Math coprocessor no
DMA no
Battery backed clock plug-in module
Onboard RAM 64K
BIOS/bootstrap EPROM 1 32K socket
Spare memory sockets no
Serial ports 2
Parallel printer port yes
No. of floppy drives 4
Type of floppy drives 360K,720K
SCSI bus interface yes
Keyboard port no (Note 3)
Speaker port no
Video controller no (Note 3)
Expansion bus via SCSI (Note 4)
Operating system CP/M, Z-System
Software usable Any CP/M program
Power consumption (typ) 5 watts
Performance (Norton SI) ---
----------------------------------------------------------------
Notes:
(1) The LB/PC has two spare byte-wide memory sockets which
can be used as "solid state disk drives", with
capacities of up to 128K bytes EPROM or 512K bytes
NOVRAM storage each.
(2) Two of the four serial ports of the LB/186-EXP/186
board set support both synchronous and asynchronous
protocols, and can be jumpered for either RS232C or
RS422 signal levels.
(3) The keyboard and video display functions are normally
supplied by an RS232 ASCII terminal on one of the
board's serial ports.
(4) The SCSI interface can be used to connect data
acquisition & control interfaces if it is not required
as a SCSI device interface.
----------------------------------------------------------------
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Trademarks and registered trademarks: IBM, PC/XT, PC-AT: International
Business Machines Corporation; CP/M, Concurrent: Digital Research
Incorporated; Z80, Zilog; Little Board, Little Board/Z80, Little Board/186,
Little Board/PC, StackPlane: AMPRO Computers Incorporated.
-------------------------------------------------------------------------------
Copyright 1987, AMPRO Computers Inc. -- All rights reserved.
-------------------------------------------------------------------------------