                    --------------------------------------
                    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.
      ----------------------------------------------------------------



-------------------------------------------------------------------------------
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.
-------------------------------------------------------------------------------


