KERNEL
MULTIPLE TASK AND PROCESS CONTROL
PRIORITY PROCESS SCHEDULING
INTER-PROCESS COMMUNICATIONS (IPC) PRIMITIVES
SYSTEM PROCESSES
MEMORY MANAGEMENT
TASK MANAGEMENT
DEVICE MANAGEMENT
FILE MANAGEMENT
NETWORK MANAGEMENT
DEVICE AND INTERRUPT HANDLERS
COMMON DEVICE AND INTERRUPT SPECIFIC CODE
SYSTEM COMMON PROCEDURES
DEVELOPMENT LIBRARIES FOR COMMON BTOS FUNCTIONS
AND PROCEDURES
UNIFORM INTERFACE FOR CONSISTENT APPLICATION DEVELOPMENT
INTEGRATED COMMAND INTERPRETER EXECUTIVE
FORMS ORIENTED COMMAND INTERPRETER
PROVIDES OPERATOR INTERFACE WITH 'HELP' FACILITY
MAY BE REPLACED BY CUSTOM APPLICATION
BTOS MANAGEMENT FACILITIES
MEMORY AND PARTITION MANAGEMENT
TASK AND PROCESS MANAGEMENT
INTERRUPT MANAGEMENT
INTER-PROCESS COMMUNICATIONS MANAGEMENT
FILE MANAGEMENT
TIMER MANAGEMENT
VIDEO MANAGEMENT
KEYBOARD MANAGEMENT
PARAMETER MANAGEMENT
DISK MANAGEMENT
SYSTEM SERVICES MANAGEMENT
QUEUE MANAGEMENT
SPOOLER MANAGEMENT
MOUSE MANAGEMENT
CLUSTER MANAGEMENT
CONTINGENCY MANAGEMENT
CONFIGURATION MANAGEMENT
MEMORY AND PARTITION MANAGEMENT
THE MEMORY AND PARTITION MANAGEMENT FACILITY SUPPORTS THE DYNAMIC
ALLOCATION AND DE-ALLOCATION OF AREAS OF MEMORY FOR STORAGE OF OBJECT CODE
AND DATA.
TWO TYPES OF MEMORY ALLOCATION ARE AVAILABLE:
LONG-LIVED MEMORY - EXPANDING DOWNWARD FROM
HIGH MEMORY LOCATIONS
SHORT-LIVED MEMORY - EXPANDING UPWARD FROM
LOW MEMORY LOCATIONS
SHORT-LIVED MEMORY:
IS ALLOCATED BY BTOS WHEN A TASK IS INITIATED
IS DE-ALLOCATED WHEN A TASK TERMINATES
CAN BE ALLOCATED / DE-ALLOCATED BY A SPECIFIC
TASK REQUEST
LONG-LIVED MEMORY:
IS ALLOCATED / DE-ALLOCATED BY A SPECIFIC
TASK REQUEST
CAN BE USED TO PASS PARAMETERS TO THE NEXT
TASK
TERMS USED IN ADDRESSING MEMORY INCLUDE:
PHYSICAL MEMORY ADDRESS
MEMORY ADDRESS OF A BYTE
NOT NORMALLY USED BY BTOS
SEGMENT ADDRESS
POINTS AT THE FIRST BYTE OF AN AREA OF MEMORY
HIGH ORDER PART OF A PHYSICAL MEMORY ADDRESS
OFFSET ADDRESS
BYTE ADDRESS RELATIVE TO A SEGMENT ADDRESS
LOW ORDER PART OF A PHYSICAL MEMORY ADDRESS
LOGICAL MEMORY ADDRESS
POINTER CONSISTING OF A SEGMENT AND OFFSET
ADDRESS
PHYSICAL ADDRESS IS SUM OF SEGMENT AND OFFSET
ADDRESS
BTOS USES LOGICAL MEMORY ADDRESSING WHENEVER POSSIBLE
PHYSICAL MEMORY IS ALLOCATED AND DE-ALLOCATED IN PAGES
PAGES ARE FIXED LENGTH PHYSICAL MEMORY AREAS
IN REAL MODE A PAGE IS 16 WORDS LONG AND
CALLED A PARAGRAPH
A MEMORY SEGMENT:
IS A CONTIGUOUS AREA OF MEMORY
CONSISTING OF AN INTEGRAL NUMBER OF PAGES
MEMORY SEGMENTS CAN BE:
ADJACENT,
DISJOINTED AND
PARTIALLY OR TOTALLY OVERLAPPING
(A PHYSICAL MEMORY LOCATION CAN BE IN MULTIPLE SEGMENTS}
THREE TYPES OF SOFTWARE MEMORY SEGMENTS:
CODE - PROCESSOR INSTRUCTIONS
STATIC DATA - LOADED INTO MEMORY FROM TASK
IMAGE
DYNAMIC DATA - ALLOCATED BY REQUEST OF THE
APPLICATION
MAIN MEMORY IS ORGANIZED INTO PARTITIONS
A PARTITION CONSISTS OF A VARIABLE NUMBER
OF SEGMENTS
APPLICATION TASKS EXECUTE IN PARTITIONS
BTOS MAINTAINS THREE TYPES OF PARTITIONS:
SYSTEM:
BTOS AND SYSTEM SERVICE APPLICATION
PRIMARY APPLICATION: THE APPLICATION
SYSTEM CONTROLLING THE KEYBOARD AND VIDEO DISPLAY
SECONDARY APPLICATION: BACKGROUND APPLICATION
SYSTEMS
LOADING A APPLICATION TASK FOR EXECUTION CONSISTS OF:
ASSIGNING A PARTITION
ALLOCATING SHORT-LIVED MEMORY TO HOLD THE
TASK IMAGE
READING THE TASK IMAGE INTO THE SHORT-LIVED
MEMORY
ADJUSTING LOGICAL MEMORY ADDRESSES IN THE
TASK
SCHEDULING THE TASK FOR EXECUTION BY PRIORITY
TASK AND PROCESS MANAGEMENT
THE TASK AND PROCESS MANAGEMENT FACILITY PROVIDES:
EVENT-DRIVEN PRIORITY SCHEDULING OF APPLICATIONS
DYNAMIC CONTROL OF MULTIPLE TASKS AND PROCESSES
AN APPLICATION SYSTEM:
IS COMPOSED OF 1 TO N TASKS AND PROCESSES
EXECUTES IN A SPECIFIC AREA OF MAIN MEMORY
A TASK IS AN EXECUTABLE PROGRAM THAT CONSISTS OF:
OBJECT CODE,
DYNAMIC / STATIC DATA AND
ONE OR MORE PROCESSES
A PROCESS IS:
THE BASIC ELEMENT OF COMPUTATION THAT USES
A PROCESSOR
SCHEDULED FOR EXECUTION BASED ON PRIORITIES
AND EVENTS
A TASK IMAGE IS:
THE DISK RESIDENT IMAGE OF AN EXECUTABLE
PROGRAM
CREATED BY LINKING COMPILER PRODUCED OBJECT
MODULES
CENTRAL PROCESSOR SCHEDULING IS DETERMINED BY PROCESS PRIORITY
A PROCESS PRIORITY CAN RANGE FROM A HIGH OF 0 TO A LOW OF 254
PRIORITY 255 IS RESERVED FOR A BTOS NULL
PROCESS
A PROCESS CONTROLS THE CENTRAL PROCESSOR UNTIL:
IT VOLUNTARILY RELINQUISHES CONTROL
AN EVENT CAUSES A HIGHER PRIORITY PROCESS
TO EXECUTE
A PROCESSOR TIME SLICE (AVAILABLE)
A PROCESS CAN EXIST IN ONE OF FOUR STATES:
RUNNING: EXECUTING INSTRUCTIONS
IN THE PROCESSOR
READY: PRIORITY
QUEUED, READY FOR EXECUTION
WAITING: WAITING AT AN EXCHANGE
FOR A MESSAGE (IPC)
SUSPENDED: STOPPED FOR BTOS SYSTEM REASONS
INTERRUPT MANAGEMENT
PROVIDES THE MECHANISMS FOR HANDLING INTERRUPTS
AN INTERRUPT:
HALTS THE SEQUENTIAL EXECUTION OF PROCESSOR
INSTRUCTIONS
SAVES THE CURRENT CONTEXT (SOFTWARE AND
HARDWARE REGISTERS)
ENTERS THE APPROPRIATE INTERRUPT HANDLER
AFTER THE INTERRUPT CONDITION IS RESOLVED, BTOS EITHER
RESTORES THE CURRENT PROCESS AND RESUMES
EXECUTION
SELECTS A HIGHER PRIORITY PROCESS TO RESUME
EXECUTION
INTERRUPTS CAN BE EITHER:
EXTERNAL:
HARDWARE ORIENTED
INVALID MEMORY ADDRESS, PARITY, POWER
FAILURE,
MASKABLE OR NON-MASKABLE
INTERNAL:
LOCAL TO PROCESSOR
I.E. DIVIDE BY ZERO, OVERFLOW, INT INSTRUCTION,
ALSO KNOWN AS TRAPS
PSEUDO:
IMPLEMENTED IN SOFTWARE
I.E. PROGRAM TIMER
HANDLERS ARE PROVIDED FOR EACH EXPECTED TYPE OF INTERRUPT
UNEXPECTED INTERRUPTS CAUSE THE SYSTEM TO 'CRASH' AND RE-INITIALIZE
FOUR KINDS OF INTERRUPT HANDLERS:
MEDIATED RAW TRAP COMMUNICATIONS
MEDIATED INTERRUPT HANDLER
PERMIT AUTOMATIC INTERRUPT NESTING BY PRIORITY
CAN COMMUNICATE ITS RESULTS TO A PROCESS
CAN BE WRITTEN IN FORTRAN, PASCAL OR ASSEMBLER
LANGUAGE
RAW INTERRUPT HANDLER
DISABLES ALL INTERRUPTS WHILE PROCESSING
PROVIDES THE FASTEST EXECUTION FOR HIGH-SPEED
DEVICES
CAN SERVICE INTERNAL OR EXTERNAL INTERRUPTS,
BUT NOT PSEUDO
CONVERTS TO MEDIATED INTERRUPT HANDLER TO
INFORM A PROCESS
USUALLY WRITTEN IN ASSEMBLER LANGUAGE
TRAP INTERRUPT HANDLER
A SPECIALIZED RAW INTERRUPT HANDLER FOR
(INT) INSTRUCTION
USED FOR ENTRY INTO HOSTED OPERATING SYSTEMS
(MS-DOS)
ENVIRONMENT OF TRAP HANDLER IS PARTITION
WHERE ESTABLISHED
COMMUNICATIONS INTERRUPT HANDLER
SUPPORTS SERIAL I/O COMMUNICATIONS CONTROLLER
CONTROLLER SUPPORTS TWO RS232/V.24 COMMUNICATIONS
CHANNELS
SAME HANDLER CAN SERVICE BOTH COMMUNICATIONS
CHANNELS
THIS HANDLER NORMALLY SUPPLIED IN SUPPORT
OF:
STANDARD ASYNCHRONOUS, SYNCHRONOUS AND
BIT-SYNCHRONOUS
EMULATORS, PROTOCOLS AND GATEWAYS
CAN BE USER-WRITTEN FOR SPECIALIZED COMMUNICATIONS
NEEDS
INTERRUPT HANDLERS CAN BE WRITTEN AND LINKED INTO:
BTOS
TASKS
APPLICATION SYSTEMS
SYSTEM SERVICES
INTER-PROCESS COMMUNICATIONS MANAGEMENT (IPC)
THE INTER-PROCESS COMMUNICATIONS FACILITY PROVIDES FOR THE PASSING
OF INFORMATION (MESSAGES) BETWEEN PROCESSES.
FOR A LARGE EXTENT, THE POWER OF BTOS RESULTS FROM ITS IPC FACILITY
IPC SUPPORTS THREE MULTIPROCESSING CAPABILITIES:
COMMUNICATIONS:
TRANSMISSION OF DATA BETWEEN PROCESSES
SYNCHRONIZATION:
ENSURES THAT PROCESSES WORK TOGETHER
RESOURCE MANAGEMENT: SHARING RESOURCES IN
A CONTROLLED WAY
BTOS SYSTEM SERVICES REQUIRE IPC FOR NORMAL OPERATION
USER DEVELOPED APPLICATION SYSTEMS CAN ALSO USE IPC
IPC IS ACCOMPLISHED THROUGH THE USE OF
MESSAGES:
CONVEYS INFORMATION AND PROVIDES SYNCHRONIZATION
EXCHANGES:
A MESSAGE CENTER AND QUEUE BETWEEN PROCESSES
BTOS KERNEL PRIMITIVES: COMMON BTOS OBJECT
PROCEDURES
IPC BETWEEN PROCESSES REQUIRES:
TWO PROCESSES (CLIENT AND SERVER)
THREE BTOS KERNEL PRIMITIVES (REQUEST, RESPOND
AND WAIT)
TWO EXCHANGES (REQUEST AND RESPONSE)
MESSAGE (REQUEST BLOCK)
THE CLIENT PROCESS:
ALLOCATES AND MANAGES THE REQUEST EXCHANGE
ALLOCATES AND MANAGES THE REQUEST MESSAGES
USES THE BTOS KERNEL PRIMITIVES SEND AND
WAIT
THE SERVER PROCESS:
ALLOCATES AND MANAGES THE RESPONSE EXCHANGE
ALLOCATES AND MANAGES THE RESPONSE MESSAGE
USES THE BTOS KERNEL PRIMITIVES SEND AND
WAIT
THE BTOS IPC KERNEL PRIMITIVES:
REQUEST PRIMITIVE
QUEUES A REQUEST FROM A CLIENT PROCESS TO
THE
REQUEST EXCHANGE OF A SERVICE PROCESS
RESPOND PRIMITIVE
USED BY A SERVICE PROCESS TO QUEUE A RESPOND
IN THE
EXCHANGE OF A WAITING CLIENT PROCESS
WAIT PRIMITIVE
USED TO SUSPEND A PROCESS EXECUTION UNTIL
A MESSAGE
IS AVAILABLE AT AN EXCHANGE
IPC EXCHANGES ARE ALLOCATED IN THREE WAYS:
AT BTOS SYSTEM BUILD TIME FOR SOME SYSTEM
SERVICES
DYNAMICALLY ALLOCATED AS NEEDED BY APPLICATION
SYSTEMS
DYNAMICALLY DE-ALLOCATED AS NEEDED BY APPLICATION
SYSTEMS
A DEFAULT RESPONSE EXCHANGE IS ASSIGNED
AT PROCESS EXECUTION
THE MESSAGE (REQUEST BLOCK) CONSISTS OF FIVE PARTS:
A STANDARD HEADER
REQUEST SPECIFIC CONTROL INFORMATION
A ROUTING CODE
DESCRIPTIONS OF THE REQUEST DATA ITEMS
DESCRIPTIONS OF THE RESPONSE DATA ITEMS
DATA ITEMS
STANDARD IPC (TWO WAY) BETWEEN TWO PROCESSES WOULD BE:
SERVER PROCESS:
'WAIT'S FOR REQUEST MESSAGE IN SERVICE EXCHANGE
CLIENT PROCESS:
PREPARES REQUEST MESSAGE FOR SERVICE TO
PROCESS
SENDS MESSAGE TO REQUEST EXCHANGE USING
'REQUEST'
WAITS FOR MESSAGE IN RESPONSE EXCHANGE USING
'WAIT'
SERVER PROCESS:
AWAKES AND PROCESSES REQUEST MESSAGE FROM
CLIENT
PREPARES RESPONSE MESSAGE FOR CLIENT TO
PROCESS
SENDS MESSAGE TO RESPONSE EXCHANGE USING
'RESPOND'
CLIENT PROCESS:
AWAKES AND PROCESSES RESPONSE FROM SERVER
A FILTER PROCESS IS A SPECIAL IPC SERVICE USED TO MODIFY
AND ADD-VALUE TO STANDARD SERVICE PROCESS
INTERCEPT MESSAGES FOR SPECIAL PASSWORD
VALIDATION
INTERCEPT MESSAGES FOR SPECIAL BACKUP LOGGING
SPECIAL ENCRYPTION OF DATA IN MESSAGES
SUPPLY A SPECIAL GATEWAY BETWEEN INCONSISTENT
PROCESSES
A FILTER PROCESS IS INTERPOSED BETWEEN CLIENT & SERVICE PROCESS
INTERACTION OF A FILTER PROCESS WOULD BE:
SERVER PROCESS:
'WAIT'S FOR REQUEST MESSAGE IN SERVICE EXCHANGE
FILTER PROCESS:
'WAIT'S FOR REQUEST MESSAGE IN FILTER EXCHANGE
CLIENT PROCESS:
PREPARES REQUEST MESSAGE FOR SERVICE TO
PROCESS
SENDS MESSAGE TO (FILTER) EXCHANGE USING
'REQUEST'
FILTER PROCESS:
AWAKES AND PROCESSES REQUEST MESSAGE FROM
CLIENT
PREPARES FILTERED MESSAGE FOR SERVICE TO
PROCESS
SENDS MESSAGE TO REQUEST EXCHANGE USING
'RESPOND'
SERVER PROCESS:
AWAKES AND PROCESSES REQUEST MESSAGE FROM
CLIENT
PREPARES RESPONSE MESSAGE FOR CLIENT TO
PROCESS
SENDS MESSAGE TO (FILTER) EXCHANGE USING
'RESPOND'
FILTER PROCESS:
AWAKES AND PROCESSES RESPONSE FROM SERVER
SENDS MESSAGE TO (CLIENT) EXCHANGE USING
'RESPOND'
CLIENT PROCESS:
AWAKES AND PROCESSES RESPONSE FROM SERVER
(FILTER)
IPC IS SUPPORTED IN A SPECIAL WAY FOR CLUSTER CONFIGURATIONS
IN THE CLUSTER CONFIGURATION,
IPC IS EXTENDED TO PROVIDE TRANSPARENT ACCESS
FROM CLUSTER
WORKSTATIONS TO SERVER PROCESSES THAT EXECUTE
AT THE
MASTER WORKSTATION
THIS EXTENSION IS PROVIDED THROUGH A IPC
FILTER OPERATION BY
THE BTOS INTER-STATION COMMUNICATION (ISC) FACILITY
FILE MANAGEMENT
THE FILE MANAGEMENT FACILITY PROVIDES FOR METHODS FOR MANAGING
DISK FILES
A DISK FILE IS A COLLECTION OF DISK SECTORS UNDER A GIVEN NAME
A DISK FILES ARE ORGANIZED ON DISK BY:
[ VOLUME ] DEVICE - LOGICAL OR HARDWARE NAME
< DIRECTORY > NAME OF A SET OF FILES
FILE-NAME SPECIFIC FILE NAME
DISK FILE PASSWORD PROTECTION IS AT THE FOLLOWING LEVELS:
DEVICE - VOLUME - DIRECTORY - FILE-NAME
FILE MANAGEMENT PROVIDES ACCESS TO DISK FILE DATA AS:
RANDOMLY ADDRESSED 512 BYTE SECTORS
UP TO 127 SECTORS CAN BE READ OR WRITTEN
IN SINGLE REQUEST
DATA TRANSFER IS DIRECTLY FROM DISK TO REQUESTING
BUFFER
FILE MANAGEMENT EFFICIENCY IS PROVIDED IN THE FOLLOWING WAYS:
CAREFUL DATA PLACEMENT {MINIMIZE DISK HEAD
MOVEMENT}
RANDOMIZATION (HASHING) TECHNIQUES {MINIMIZING
DISK READS}
FILE MANAGEMENT RELIABILITY IS PROVIDED IN THE FOLLOWING WAYS:
MULTILEVEL PASSWORD PROTECTION {VOLUME,
DIRECTORY OR FILE}
MULTIPLE FILE PROTECTION LEVELS {FILE EXPANSION,
ETC.}
DUPLICATION OF TWO VOLUME CONTROL STRUCTURES
{VHB AND FHB}
FILE MANAGEMENT CONVENIENCE IS PROVIDED IN THE FOLLOWING WAYS:
SIMPLE ORGANIZATION OF DISK FILE DATA
SUPPORTS LONG FILE NAMES
DYNAMIC FILE LENGTHS {FILE MUST FIT ON ONE
DISK}
AUTOMATIC RECOGNITION OF VOLUMES PLACED
ON-LINE
READ (SHARED) OR MODIFY (EXCLUSIVE) FILE
MODES
DEVICE INDEPENDENCE {DEVICE IS TRANSPARENT
TO USER}
IN A CLUSTER CONFIGURATION,
FILES CAN BE LOCATED AT CLUSTER WORKSTATIONS
USING LOCAL DISK STORAGE,
AS WELL AS AT THE MASTER WORKSTATION DISK
STORAGE
AN APPLICATION DEVELOPER CAN IN ANY OPEN FILE:
READ OR WRITE A 512 BYTE SECTOR WITH ONE
DISK ACCESS
READ OR WRITE UP TO 65,024 BYTES WITH ONE
DISK OPERATION
OVERLAP INPUT AND OUTPUT WITH PROCESS EXECUTION
OPTIMIZE DISK ARM SCHEDULING
FILE ACCESS METHODS AUGMENT FILE MANAGEMENT
- FILE MANAGEMENT ORGANIZES DATA IN 512
BYTE SEGMENTS
- FILE ACCESS METHODS ORGANIZE DATA AS ONE
OF THE FOLLOWING:
AN UNSTRUCTURED SEQUENCE OF
BYTES (SAM)
A SEQUENCE OF VARIABLE-LENGTH
RECORDS (RSAM)
A SEQUENCE OF FIXED-LENGTH
RECORDS (DAM AND ISAM)
SEQUENTIAL ACCESS METHOD (SAM):
UNSTRUCTURED SEQUENCE OF BYTES
SEQUENTIAL INPUT/OUTPUT
AUTOMATIC OVERLAPPED INPUT/OUTPUT
FILES CAN BE OPENED FOR READ, WRITE AND
APPEND
RECORD SEQUENTIAL ACCESS METHOD (RSAM):
SEQUENCE OF FIXED OR VARIABLE-LENGTH RECORDS
SEQUENTIAL INPUT/OUTPUT
AUTOMATIC OVERLAPPED INPUT/OUTPUT
FILES CAN BE OPENED FOR READ, WRITE AND
APPEND
OPERATIONS FOR SCANNING FORWARD TO NEXT
WELL-FORMED RECORD
DIRECT ACCESS METHOD (DAM):
SEQUENCE OF NUMBERED, FIXED-LENGTH RECORDS
RANDOM INPUT/OUTPUT BY RECORD NUMBER
NON-OVERLAPPED INPUT/OUTPUT
FILES CAN BE OPENED FOR READ OR MODIFY
INDEXED SEQUENTIAL ACCESS METHOD (ISAM):
A MULTI-KEY, MULTI-USER ACCESS METHOD
SEQUENCE OF KEYED, FIXED-LENGTH RECORDS
RANDOM AND SEQUENTIAL INPUT/OUTPUT
NON-OVERLAPPED INPUT/OUTPUT
USES DAM ACCESS METHODS
DATA SET IS MAINTAINED IN TWO PHYSICAL FILES:
INDEX FILE
HOLDS INDEXES FOR ALL KEYS
IN A DATA SET
DATA STORE FILE
HOLDS THE DATA RECORDS
TIMER MANAGEMENT
THE TIMER MANAGEMENT FACILITY PROVIDES CURRENT DATE AND TIME
THE TIMER MANAGEMENT FACILITY HAS FOUR FUNCTIONS:
REAL-TIME CLOCK
PROGRAMMABLE INTERVAL TIMER
MAINTAIN DAY, DATE AND TIME DATA STRUCTURES
DELAY
THE REAL-TIME CLOCK PROVIDES:
TIME AND DATE FOR EACH WORKSTATION
REAL-TIME CLOCK INTERRUPT HANDLER
ONE SHOT TIMING IN 100 MS INTERVALS
REPETITIVE TIMER IN 100 MS INTERVALS
THE PROGRAMMABLE INTERVAL TIMER IS PROVIDES HIGH RESOLUTION TIME FOR PSEUDO-INTERRUPT HANDLERS
THE DAY, DATE AND TIME DATA STRUCTURES PROVIDE
TIME TO AN ACCURACY OF 1 SECOND
DATES UP TO THE YEAR 2042
THE DELAY FACILITY ALLOWS A PROCESS TO BE SUSPENDED FOR A SPECIFIC
INTERVAL IN MULTIPLES OF 100 MS
VIDEO MANAGEMENT
THE VIDEO MANAGEMENT FACILITY PROVIDES FOR THE DISPLAY OF
ALPHANUMERIC INFORMATION BY AN APPLICATION SYSTEM
VIDEO MANAGEMENT CONSISTS OF HARDWARE AND SOFTWARE:
VIDEO CONTROLLER HARDWARE
VIDEO CONTROL SOFTWARE
LOADABLE SOFT FONT TABLE
SOFT FONT DESIGN PROGRAM
THE VIDEO CONTROLLER HARDWARE LOCATED IN THE PROCESSOR MODULE:
READS CHARACTERS AND ATTRIBUTES FROM THE
4096 WORD
(8192 CHARACTER) VIDEO CHARACTER MAP
EMPLOYS A MODIFIABLE 4096 WORD VIDEO FONT
RAM (SOFT FONT)
CONVERTS THE CHARACTERS TO A PATTERN OF
DOTS (PIXELS) FOR THE VIDEO DISPLAY
THE VIDEO IS TREATED AS A NUMBER OF RECTANGULAR AREAS (FRAMES)
UP TO EIGHT FRAMES CAN BE DYNAMICALLY DEFINED
AND MANAGED
THE PURPOSE OF EACH FRAME IS APPLICATION
SYSTEM DEPENDENT
SUPPORTS HORIZONTAL WINDOWS
VIDEO CHARACTER ATTRIBUTES INCLUDE:
BLINKING BOLD HALF-BRIGHT
REVERSE VIDEO STRUCK-THROUGH UNDERLINE
VIDEO LINE ATTRIBUTES INCLUDE:
DOUBLE-HIGH CHARACTERS (B27)
DOUBLE-WIDE CHARACTERS (B27)
VIDEO DISPLAY ATTRIBUTES INCLUDE:
VARIABLE NUMBER OF LINES (1-34)
VARIABLE NUMBER OF COLUMNS (1-132)
THREE LEVELS OF VIDEO SOFTWARE CONTROL ARE PROVIDED:
VIDEO DISPLAY MANAGEMENT (VDM)
VIDEO ACCESS METHOD (VAM)
VIDEO SEQUENTIAL ACCESS METHOD (SAM)
THE VDM FACILITY PROVIDES DIRECT CONTROL OVER THE VIDEO HARDWARE
DETERMINE THE LEVEL OF VIDEO HARDWARE PRESENT
LOAD A NEW CHARACTER FONT INTO THE FONT
RAM
CHANGE SCREEN ATTRIBUTES WHILE THE SCREEN
IS BEING REFRESHED
STOP VIDEO REFRESH
DEFINE VIDEO FRAMES
INITIALIZE EACH VIDEO FRAME
INITIALIZE THE CHARACTER MAP
THE VDM FACILITY IS THE MOST EFFECTIVE METHOD OF MANAGING THE VIDEO
THE VAM FACILITY PROVIDES:
A SET OF SYSTEM COMMON PROCEDURES
DIRECT ACCESS TO THE CHARACTERS AND ATTRIBUTES
OF EACH FRAME
VAM OPERATIONS INCLUDE:
PLACE A CHARACTER STRING ANYWHERE IN A FRAME
SPECIFY CHARACTER ATTRIBUTES FOR A STRING
SCROLL A FRAME UP OR DOWN
POSITION A CURSOR IN A FRAME
BLANK A FRAME
THE VAM FACILITY IS:
IDEAL FOR FORMS-ORIENTED INTERACTION
CONVENIENT FOR ADVANCED TEXT PROCESSING
THE VIDEO SAM FACILITY PROVIDES VIDEO ACCESS THROUGH BYTE STREAMS
THE VIDEO SAM VIDEO BYTE STREAMS SUPPORT:
MULTIPLE FRAMES
CHARACTER ATTRIBUTES
POSITIONING OF A CHARACTER IN A FRAME
CURSOR POSITIONING
STANDARD SAM OPERATIONS ARE AUGMENTED FOR THE VIDEO BY THE FOLLOWING:
SPECIAL CHARACTER INTERPRETATIONS
MULTIPLE ESCAPE SEQUENCES THAT CONTROL THE
VIDEO CAPABILITY
DEVICE DEPENDENT OPERATION THAT RETURNS
INFORMATION ON THE VIDEO
KEYBOARD MANAGEMENT
THE KEYBOARD MANAGEMENT FACILITY ENABLES AN APPLICATION SYSTEM
TO CONTROL THE KEYBOARD
THE KEYBOARD IS MANAGED BY A CUSTOMIZABLE TRANSLATION TABLE
SUPPORTS 256 KEY KEYBOARDS
ATTRIBUTES FOR EACH KEY INCLUDE:
KEY REPEAT START TIME
KEY REPEAT RATE
IMPACT OF 'LOCK' KEY ON SHIFTED CHARACTER
BTOS KEYBOARD MANAGEMENT SUPPORTS A LARGE VARIETY OF KEYBOARDS
THE APPLICATION SYSTEM CAN REQUEST INPUT IN EITHER:
UN-ENCODED MODE:- ONE 8 BIT BYTE FOR EACH
KEY MOTION
CHARACTER MODE :- ONE 8 BIT BYTE FOR EACH
KEY DEPRESSION
EXCEPT: SHIFT, CODE, LOCK OR ACTION KEYS
THE MICROPROCESSOR IN THE KEYBOARD SUPPORTS UN-ENCODED MODE:
EACH DEPRESSION AND RELEASE OF A KEY GENERATES
A 8 BIT BYTE
THE 8 BIT BYTE IDENTIFIES THE KEY AND THE
DIRECTION OF MOTION
KEYBOARD MANAGEMENT DIRECTLY SUPPORTS CHARACTER MODE:
REMEMBERS KEYS AS THEY ARE DEPRESSED
DETERMINES WHEN A SPECIFIC CHARACTER HAS
BEEN TYPED
CONVERTS THAT CHARACTER USING THE KEYBOARD
ENCODING TABLE
SUPPLIES THE ENCODED CHARACTER TO THE APPLICATION
SYSTEM
KEYBOARD LED INDICATORS ARE CONTROLLED BY THE APPLICATION SYSTEM
KEYBOARD MANAGEMENT SUPPORTS A TYPE-AHEAD BUFFER OF 128 BYTES
KEYBOARD MANAGEMENT DOES NOT ECHO CHARACTERS TO THE VIDEO DISPLAY
THE APPLICATION SYSTEM IS FREE TO INTERPRET EACH KEY AS NEEDED
THE 'ACTION' KEY IS A TYPE OF SHIFT KEY AND PROCESSED SPECIAL BY KEYBOARD MANAGEMENT.
THE 'ACTION' KEY MODIFIES THE INTERPRETATION OF OTHER KEYS:
'ACTION-DELETE' :
CLEARS THE TYPE AHEAD BUFFER
'ACTION-OVER TYPE' :
TURNS OFF THE VIDEO DISPLAY REFRESH
'ACTION-FINISH' :
ENDS THE EXECUTION OF THE APPLICATION
SYSTEM
( IF NOT OVERRIDDEN BY APPLICATION
)
'ACTION-A' AND 'ACTION-B' :
INVOKE THE `DEBUGGER' FACILITY
OTHER 'ACTION' KEY COMBINATION :
AVAILABLE FOR THE APPLICATION
PARAMETER MANAGEMENT
PROVIDES A STRUCTURED MECHANISM FOR PASSING INFORMATION FROM ONE
APPLICATION SYSTEM TO IT'S SUCCESSOR IN THE SAME PARTITION
PARAMETERS ARE PASSED IN A VARIABLE LENGTH PARAMETER BLOCK (VLPB)
THE VLPB IS ALLOCATED AND INITIALIZED BY THE PASSING APPLICATION
THE VLPB IS ANALYZED BY THE SUCCESSOR APPLICATION
PARAMETER PASSING MUST TAKE PLACE IN THE SAME PARTITION
TWO TYPE OF PARAMETERS SUPPORTED:
REGULAR PARAMETER {CAN CONSIST OF ZERO OR
MORE SUB-PARAMETERS}
SUB-PARAMETER {ARBITRARY SEQUENCE OF NON-BLANK
CHARACTERS}
USERS OF PARAMETER MANAGEMENT INCLUDE:
BTOS EXECUTIVE COMMAND INTERPRETER
BATCH MANAGER
DISK MANAGEMENT
THE DISK MANAGEMENT FACILITIES PROVIDE DEVICE-LEVEL ACCESS TO DISK
FILE MANAGEMENT FACILITIES PROVIDES FOR FILE-LEVEL ACCESS
DEVICE LEVEL ACCESS IS REQUIRED IN ORDER TO:
READ A FLOPPY DISKETTE WRITTEN ON A NON-B20
SYSTEM
FORMAT AN INITIALIZED DISK
DEVICE LEVEL ACCESS IS PROVIDED FOR THE FOLLOWING MEDIA
SINGLE OR DUAL SIDED,SINGLE OR DOUBLE DENSITY
5 1/4 INCH FLOPPY
THE DEVICE SPECIFICATION FOR ACCESS OF A DISK DEVICE IS:
IF THE DEVICE IS A VALID FILE SYSTEM,
[VOLUME NAME] (REQUIRES VOLUME PASSWORD)
IF THE DEVICE IS NOT A VALID FILE SYSTEM,
[DEVICE NAME] (REQUIRES DEVICE PASSWORD)
SYSTEM SERVICES MANAGEMENT
THE SYSTEM SERVICE FACILITIES PROVIDE FOR SYSTEM SERVICE PROCESSES
TO BE INSTALLED AND MAINTAINED
BTOS INCLUDES MANY SYSTEM SERVICE PROCESSES THAT ARE SYSTEM-WIDE
MANAGER FOR RESOURCES:
FILES MEMORY KEYBOARD DATA
COMMUNICATIONS ETC.
SYSTEM SERVICES ARE SCHEDULED FOR EXECUTION LIKE APPLICATION PROCESSES
SYSTEM SERVICES ARE AVAILABLE AT THE WORKSTATION WHERE INSTALLED
IF INSTALLED AT THE MASTER WORKSTATION IN
A CLUSTER,
- ALL SLAVES WORKSTATIONS CAN ACCESS THE
SYSTEM SERVICE
SYSTEM SERVICES CAN BE USER DEVELOPED AND CAN BE:
LINKED INTO BTOS FOR AUTOMATIC INSTALLATION
DYNAMICALLY INSTALLED
DYNAMICALLY DE-INSTALLED
STANDARD SYSTEM SERVICES INCLUDE
QUEUE MANAGER
SPOOLER
CONTEXT MANAGER
ISAM
QUEUE MANAGEMENT
THE QUEUE MANAGEMENT FACILITY PROVIDES A SYSTEM SERVICE FOR SUPPORTING
QUEUES
BTOS QUEUES ARE:
NAMED,
PRIORITY-ORDERED,
DISK BASED AND
ALL QUEUE INFORMATION IS CONTAINED IN QUEUE
ENTRY FILES
A QUEUE ENTRY FILE CONTAINS INFORMATION FOR A PROCESSING SYSTEM:
USER APPLICATION SYSTEM
SPOOLER (SPOOLED PRINTING)
BATCH MANAGER (SECONDARY PARTITION PROCESSING)
BSC 3270 REMOTE JOB ENTRY (RJE)
SNA RJE
QUEUE INFORMATION CAN BE CREATED AND MODIFIED
BY SERVER PROCESSES ( SPOOLER, BATCH MANAGER,
SNA RJE, ETC.)
BY CLIENT PROCESSES ( WORD PROCESSOR, USER
APPLICATION, ETC.)
SPOOLER MANAGEMENT
THE SPOOLER MANAGEMENT FACILITY PROVIDES A SYSTEM SERVICE FOR SUPPORTING
SPOOLED PRINTING
PRINTER OUTPUT IS PLACED IN A DISK FILE BEFORE PRINTING
PRINT SCHEDULING IS MANAGED BY THE QUEUE MANAGEMENT FACILITIES
SPOOLER SUPPORTS PRINTERS ATTACHED TO THE:
SERIAL (RS232/V.24) PORTS
PARALLEL (CENTRONICS COMPATIBLE) PORT
PRIORITY PRINT SCHEDULING IS SUPPORTED
INSTALLATION PARAMETERS INCLUDE:
PRINTER NAME
SCHEDULING QUEUE NAME
PRINTER CONFIGURATION FILE SPECIFICATION
THE PRIORITY OF THE PROCESS THAT CONTROLS
THE PRINTER
PRINT CONTROL OF SPOOLER BANNER PAGE
MOUSE MANAGEMENT
THE MOUSE MANAGEMENT FACILITY PROVIDES THE MECHANISM FOR SUPPORTING
A POINTING (MOUSE) DEVICE
THE MOUSE CONNECTS TO THE KEYBOARDS SPARE I-BUS CONNECTOR
A MOUSE SYSTEM SERVICE IS INSTALLED AT EACH WORKSTATION
USER SELECTABLE CURSOR SHAPE AND CURSOR MOVEMENT SPEED
OBJECT LIBRARY PROVIDED FOR USER APPLICATION DEVELOPMENT
CLUSTER MANAGEMENT
THE CLUSTER MANAGEMENT FACILITY PROVIDES THE MECHANISM FOR COMMUNICATION
BETWEEN WORKSTATIONS
CLUSTER MANAGEMENT USES THE HIGH SPEED RS422 (1.8 MEGABITS) CHANNELS IN THE B25 PROCESSOR
SUPPORTS (MASTER - SLAVE) MULTI-USER SHARING OF RESOURCES
MULTIPLE SLAVES CAN SHARE A MASTER'S RESOURCES
MASTER WORKSTATION MAINTAINS:
STATISTICS ON CLUSTER USAGE AND
STATISTICS ON ANY CHANNEL ERRORS
CONTINGENCY MANAGEMENT
THE CONTINGENCY MANAGEMENT FACILITY PROVIDES MECHANISMS FOR HANDLING
ERROR CONDITIONS
ERROR CONDITIONS CAN BE:
HARDWARE FAULTS (MEMORY PARITY ERROR, ETC.)
INCONSISTENCIES FOUND BY BTOS (BAD CHECK
SUM, ETC. )
PROBLEMS DETECTED BY APPLICATIONS PROGRAMS
BTOS TERMINATES EXECUTION WHEN IT DETECTS FATAL INCONSISTENCIES
HARDWARE FAULTS NORMALLY STOP BTOS SYSTEM OPERATION
USER-WRITTEN INTERRUPT HANDLERS CAN BE USED FOR SPECIAL HANDLING
BTOS CRASH CONDITIONS ARE RECORDED IN SYSTEM LOG FILE
BTOS RE-BOOTS AFTER ALL SYSTEM CRASHES
CONFIGURATION MANAGEMENT
THE CONFIGURATION MANAGEMENT FACILITY PROVIDES A MECHANISM FOR
AUTOMATICALLY DETERMINING WORKSTATION CONFIGURATION
THE BOOTSTRAP POLLS EACH MODULE AND BUILD THE TABLE OF ID'S
EACH MODULE OR INPUT DEVICE ON A WORKSTATION HAS AN ID NUMBER:
A 16 BIT NUMBER THAT IDENTIFIES THE TYPE OF UNIT
DATA STRUCTURES ARE MAINTAINED OF THE CONFIGURATION INFORMATION:
BTOS SYSTEM CONFIGURATION:
COMMON STRUCTURES AND PROCEDURES GIVE INFORMATION
ON:
SYSTEM HARDWARE,
OPERATING SYSTEM,
CURRENT OPERATION, ETC.
THE IDs OF ALL MODULES PRESENT ON THE SYSTEM:
X-BUS (B26/B28)
F-BUS (B27)
SERIAL DEVICE BUS (I-BUS)