Input/Output System of Minicomputers

The following sections are included:

• PREFACE

• CONTENTS

The following sections are included:

• Introduction

• Input/Output Function of a Driver

• Pseudo-driving Function of a Driver

The following sections are included:

• Introduction

• Arguments of QIO Directives
  • FUN—function code
  • LUN — logical unit number
  • EFN — event flag number
  • PRI—priority number
  • IOSB — address of a two-word I/O status block
  • AST — asynchronous trap entry
  • P1 to P6 — device-dependent parameters
  • PSCT — name of program section
  • ERR — error-handling routine address

• Three Formats of QIO Directives
  • $S format
  • $C format
  • $ format
  • FORTRAN call format

• Synchronization between User Processes and Drivers
  • Mode of queue and wait for event flag
  • Mode of simple wait for event flag
  • Mode of asynchronous trap

The following sections are included:

• Overview of Memory Management

• Relocation of Virtual Addresses

• Address Mapping of Partitions

• Address Mapping when Accessing Common Areas

• Address Mapping for Drivers
  • The necessity of address mapping
  • Two fundamental modes of address relocation
  • Relocation of multi-addresses for transfer function
  • Access of individual data

The following sections are included:

• Driver Body
  • Device mnemonics
  • Use of macros
  • Driver dispatch table DDT
  • Device initiator entry XXINI (device check entry XXCHK)
  • Cancel I/O operation entry XXCAN
  • Device time-out entry XXOUT
  • Power failure entry XXPWF
  • Dequeuing of I/O packet
  • Buffer for storing UCB address
  • Temporary buffer for storing controller sequence number
  • Terminating assembler directive

• Data Tables of Drivers
  • Overview
  • I/O packet
  • Device control block DCB
  • Unit control block UCB
  • Status control block SCB

• Interrelationship between Control Blocks and Their Code Formats
  • Interrelationship between control blocks
  • Code formats of data tables

• Classification of Drivers
  • Resident body and resident data tables
  • Loadable body and loadable data tables
  • Loadable body and resident data tables

The following sections are included:

• System Pool
  • Uses of system pool
  • Allocation of system pool

• Monitoring and Management of System Pool
  • System pool conditions defined by PMT
  • Default actions for a high pool condition
  • Default actions for a low pool condition
  • Default actions for extreme fragmentation
  • Setting of pool limit parameters

• Questions Related to SYSGEN
  • Sizes of the Executive and system pool
  • Questions concerning the device drivers

The following sections are included:

• Overview

• Requirements of Driver Code
  • Requirements of a loadable driver
  • Requirements to a resident driver

• Interrupt Service Routine
  • Programming protocol
  • Macros used by interrupt mechanism
  • ICB (Interrupt Control Block)

• Flow Control
  • Flow control for loadable drivers
  • Flow control for resident drivers

The following sections are included:

• Specifications of Line Printers
  • Hardware registers of a line printer
  • Function codes and QIO directive formats

• Data Tables of LPDRV
  • Source code of data tables
  • DCB of LPDRV
  • UCB of LPDRV
  • SCB of LPDRV

• Features of LPDRV Body
  • Driver Dispatch Table DDT
  • Initiator entry LPINI
  • Printing sub-routine LPRNT
  • Interrupt service routine $LPINT
  • Device time-out entry LPOUT
  • Power failure entry LPPWF
  • Cancel I/O operation entry LPCAN

• Source Code of LPDRV

The following sections are included:

• Common Pre-processing
  • Checking LUN legality and the effective address of UCB
  • Checking and processing of EFN (Event Flag Number) and IOSB (I/O Status Block)
  • Creating an I/O packet
  • Checking the validity of the function code
  • Setting directive status $DSW

• Function-dependent Pre-processing
  • Pre-processing for control functions
  • Pre-processing for no-operation function
  • Pre-processing for transfer function
  • Pre-processing for ACP function

• Functions of Polishing Routines

• Post-processing

In PDP computers the linking procedure is called task building and a specific process TKB is used for this purpose. From the Executive to the non-privileged user processes, all have to be linked. Drivers are no exception. When the source codes of the driver body XXDRV.MAC and data tables XXTAB.MAC have been written or corrected, they are assembled separately into the following object files:

XXDRV.OBJ and XXTAB.OBJ.

The next step is to link them into a task image file XXDRV.TSK and a symbol definition file XXDRV.STB.

The linking commands differ for the resident and loadable drivers. So they will be discussed separately as follows…

The following sections are included:

• Two Kinds of Privileged User Processes
  • Overview
  • Semi-privileged process — /PR:0 privileged process
  • Privileged processes — /PR:4 and /PR:5 privileged processes

• Connect to and Disconnect from Interrupt
  • Format of directive CINT$
  • Pre-processing of the directive to connect to interrupt
  • Pre-processing of the directive to disconnect from interrupt

• Interrupt Transfer Block ITB

• Interrupt Processing of a Privileged Process
  • Comparison with a loadable driver
  • An example—Privileged process INTPRI used for interrupt processing

The following sections are included:

• Introduction

• Management of File System

• Extending of I/O Functionality of Device Drivers

• Implementation of Communication Protocols
  • Overview
  • Physical layer
  • Network layer
  • Transport layer
  • Presentation layer
  • Application layer

The following sections are included:

• Comparison with a Driver

• Classification of ACP’s
  • Digital ACP
  • User ACP
  • Foreign ACP

• ACP-specific Data Tables
  • Window block
  • Volume control block VCB
  • ACP pool and other data tables

• ACP Implementation
  • Linking requirements
  • Pre-processing for Digital ACP’s
  • Packet processing done by a driver
  • ACP packet dequeuing
  • Packet processing done by an ACP
  • Disable operation
  • ACP packet post-processing and user process termination

ACP enable operation merely means satisfying certain conditions that allow user processes to issue I/O requests to the ACP. Essentially, an ACP can service the I/O requests of a user process only after the device is mounted or enabled. For the Digital ACP’s, mounting (enabling) a device is performed by the MOUNT command. However, the MOUNT command is not the only way. For some User ACP’s, it is simpler to write a new process ENA to enable (mount) the device. But the basic mount or enable operations are the same. So it seems reasonable that, prior to studying enable operation, we will acquaint ourselves with process MOU and its mount operation first.

The following sections are included:

• Introduction

• Data Tables of DBDRV — DBTAB
  • Source code of data tables DBTAB
  • DCB of DBDRV
  • UCB of DBDRV
  • SCB of DBDRV

• Body of DBDRV
  • Source code of DBDRV
  • Main functions of DBDRV

• Name and DQ Cell List Processing ACP — NDACP
  • Source code of NDACP
  • Main functions of NDACP

There are a number of system routines which are available to the I/O drivers and privileged user processes such as ACP’s. They can perform certain functions which are needed for I/O operations…

In Appendix C of his text Ralph W. Stamerjohn gave detailed descriptions about FCS-11 modules [19]. Readers interested in this field can refer to this text. In order to give the readers a brief idea of Stamerjohn’s text, the following are explained…

The following sections are included:

• REFERENCES

• ACRONYMS

• INDEX