OS-9 is composed of a group of modules, each of which has a spe
 cific function. The following illustration shows the major mod
 ules. Actual module names are capitalized.

 I/O System Modules


Input Output Manager

(IOMAN)






Ram CC3Disk CC3Hdisk Pipe ACIAPak ModPak CC310
 Ram Disk Disk Disk Driver Driver Driver
 Driver Driver ' Driver (Piper)

 RO DO DD D1 HO H1 Pipe T1 T2 P1 P2




                      Term Vdg GrfDrv

                      Desc


OS-9 COMPONENT MODULE ORGANIZATION
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OS-9 Technical Reference
Color Computer OS-9 Modules
    IOMAN Input/output management

    INIT System initialization table

    CLOCK Software routine time management

    RBFMAN Random block file management

    SCFMAN Sequential character file management

    PIPEMAN Pipe file management

    CC3DISK Color Computer disk driver

    CC310 Color Computer input/output driver


The VDG (video display generator) provides both interface func

tions and low-level routines for Color Computer 2 VDG

compatibility.


The GRFINT interface provides high-level graphics code interpre

tation and interface functions.


The WINDINT interface contains all the functions of GRFINT,

along with additional support for Multiview functions. If you are

using Multiview, exclude GRFINT from the system.


Both WINDINT and GRFINT use the low-level driver GRFDRV

to perform the actual drawing on bitmap screens.


Term-VDG uses CC310 and VDGINT. TERM-WIN and all

window descriptors (W, Wl, W2, and so on) use CC3I0, WIN

DINT, GRFINT, and GRFDRV modules.


Kernel, Clock Module, and INIT

The system's first level contains the kernel, clock module, and

INIT.


The kernel provides basic system services, such as multitasking

and memory management. It links all other OS-9 modules into

the system.


The clock module is a software handler for the real-time clock

hardware.


INIT is an initialization table used by the kernel during system

startup. This table loads initial tasks and specifies initial table

sizes and initial system device names. It is loaded into RAM

(random access memory) by the OS-9 bootstrap module Boot.

Boot also loads the OS9P2 and INIT modules during system

startup.


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                    System Organization / 1


There are two ways to run boot:

      Using the DOS command with Color Disk BASIC, Ver

      sion 1.1, or later.


    e Pressing the reset button after OS-9 is running.


Input/Output Modules

The remaining modules make up the OS-9 1/0 system. They are

defined briefly here and are discussed in detail in Chapter 4.


I/O Manager

The system's second level (the level below the kernel) contains

the input/output manager, IONIAN. The 1/0 manager provides

common processing for all input/output operations. It is required

for performing any input/output supported by OS-9.


File Managers

The system's third level contains the file managers. File man

agers perform 1/0 request processing for similar classes of 1/0

devices. There are three file managers:


RBF manager The random block file manager processes
 all disk 1/0 operations.
 SCF manager The sequential character file manager han
 dles all non-disk I/0 operations that operate
 one character at a time. These operations
 include terminal and printer I/0.
 PIPEMAN The pipe file manager handles pipes. Pipes
 are memory buffers that act as files. Pipes
 are used for data transfers between
 processes.
 Device Drivers

The system's fourth level contains the deuice drivers. Device

drivers handle basic I/0 functions for specific 1/0 controller hard

ware. You can use pre-written drivers, or you can write your

own.


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OS-9 Technical Reference
Device Descriptors

The system's fifth level contains the device descriptors. Device

descriptors are small tables that define the logical name, device

driver, and file manager for each I/O port. They also contain port

initialization and port address information. Device descriptors

require only one copy of each I/O controller driver used.


Shell

The shell is the command interpreter. It is a program and not a

part of the operating system. The shell is fully described in the

OS-9 Commands manual.


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