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CPM OPERATING SYSTEMS/CPM 8000 (CPM8K)/P-CP M-Z8K SOURCES/sg/sys1.tex

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+.bp
+.pn 1  
+.cs 5
+.mt 5
+.mb 6
+.pl 66
+.ll 65
+.po 10
+.hm 2
+.fm 2
+.ft All Information Presented Here is Proprietary to Digital Research
+.ce
+.tc 1  System Overview 
+.sh
+Section 1 
+.ce
+.sp
+.sh
+System Overview 
+.sp 2
+.he CP/M-8000 Operating System System Guide           1.1  Introduction
+.tc    1.1  Introduction
+.sh
+1.1  Introduction
+.qs
+.pp
+CP/M-8000 is a single-user, general purpose operating system for
+microcomputers based on the Zilog Z8000 or equivalent microprocessor 
+chip.  It is designed to be adaptable to almost any hardware environment, and 
+can be readily customized for particular hardware systems.
+.ix Zilog Z8000
+.pp
+CP/M-8000 is equivalent to other CP/M \ \ systems with changes
+dictated by the Z8000 architecture.  In particular, CP/M-8000 supports the
+very large segmented address space of the Z8000 family.  
+The CP/M-8000 file system
+is upwardly compatible with CP/M-80 \ \ version 2.2 and CP/M-86 \ \ Version 
+1.1.  The CP/M-8000 file structure allows files of up to 32 megabytes per 
+file.   CP/M-8000 supports from one to sixteen disk drives with as many as 
+512 megabytes per drive.
+.ix address space
+.ix CP/M-8000 file structure
+.pp
+The entire CP/M-8000 operating system resides in memory at all times,
+and is not reloaded at a warm start.  CP/M-8000 can be configured to reside in 
+any portion of memory.
+The remainder of the address space is available for applications programs, 
+and is called the transient program area, TPA.  
+The TPA is assumed to consist of one or more complete (64 Kbyte) 
+memory segments.
+CP/M-8000 supports both segmented and non-segmented user programs, and
+supports the splitting of user program and data into separate addressing
+spaces.
+.ix TPA
+.pp
+Several terms used throughout this manual are defined in Table 1-1.
+.sp 2
+.ce
+.sh
+Table 1-1.   CP/M-8000 Terms
+.sp
+.nf
+       Term                            Meaning               
+.sp
+.fi
+.ll 60
+.in 25
+.ti -20
+nibble              4-bit half-byte
+.sp
+.ti -20
+byte                8-bit value
+.sp
+.ti -20
+word                16-bit value
+.sp
+.ti -20
+longword            32-bit value
+.sp
+.ti -20
+address             32-bit identifier of a storage location
+.sp
+.ti -20
+physical address    address of a location in real memory
+.sp
+.ti -20
+logical address     address as issued by a program, possibly requiring
+translation into a physical address.
+.sp
+.ti -20
+offset              a value defining an address in storage; a fixed 
+displacement from some other address
+.ix nibble
+.ix byte
+.ix word
+.ix longword
+.ix address
+.ix physical address
+.ix logical address
+.ix offset
+.sp
+.ti -20
+.bp
+.ll 60
+.ce
+.in 0
+.sh
+Table 1-1.  (continued)
+.sp 2
+         Term                          Meaning
+.sp
+.in 25
+.ti -20
+text segment        program section containing machine instructions
+.sp
+.ti -20
+data segment        program section containing initialized data
+.sp
+.ti -20
+block storage       program section containing uninitialized data
+.ti -20
+segment (bss)
+.sp
+.ti -20
+absolute            describes a program which must reside at a fixed memory 
+address.
+.sp
+.ti -20
+relocatable         describes a program which includes relocation information 
+so it can be loaded into memory at any address
+.ix text segment
+.ix data segment
+.ix block storage
+.ix absolute
+.ix relocatable
+.ix CP/M-8000 programming model
+.ix bss
+.ix transient program
+.ix base page 
+.in 0
+.ll 65
+.sp
+.pp
+The CP/M-8000 programming model is described in detail in the \c
+.ul
+CP/M-8000 Operating System Programmer's Guide.
+.qu
+\  To summarize that model briefly, CP/M-8000 supports four segments within 
+a program:  text, data, block storage segment (bss), and stack.  When a 
+program is loaded, CP/M-8000 allocates space for all four segments in the TPA, 
+and loads the text and data segments.  A transient program may manage free
+memory using values stored by CP/M-8000 in its base page.
+.pp
+If the program is to run in segmented mode, 
+the allocation of program segments to logical address segments must
+have been done at link time.  If the program is to run in non-segmented
+mode, however, information in the Memory Region Table is used to
+decide which physical segments to run the program in.  If the program
+is to run with split program and data spaces, two physical segments
+are required (with the data, bss, and stack in the same physical
+segment), otherwise only a single physical segment is used.
+
+	=== THIS LEAVES SOMETHING TO BE DESIRED ===
+	=== CLARITY, FOR EXAMPLE                ===
+.bp
+.nf
+.ll 60
+                             USER         
+
+
+
+
+                       User Interface    
+
+                            (CCP)        
+
+
+
+
+
+
+                        Programming    
+                        Interface      
+
+
+                         (BDOS)
+
+
+
+
+
+
+                         Hardware
+                        Interface
+
+                         (BIOS)
+
+
+
+
+
+                   HARDWARE ENVIRONMENT 
+.sp
+.ce
+.sh
+Figure 1-1.  CP/M-8000 Interfaces
+.qs
+.ll 65
+.in 0
+.ce 0
+.fi
+.he CP/M-8000 Operating System System Guide  1.2  CP/M 8000 Organization
+.cp 6
+.sp 2
+.tc    1.2.  CP/M-8000 Organization 
+.sh
+1.2  CP/M-8000 Organization
+.pp
+CP/M-8000 comprises three system modules:  the Console Command Processor (CCP)
+the Basic Disk Operating System (BDOS) and the Basic Input/Output System
+(BIOS).  These modules are linked together to form the operating system.
+They are discussed individually in this section.
+.ix CCP
+.ix BDOS
+.ix BIOS
+.ix CP/M-8000 , system modules
+.ix interrupt vector area
+.he CP/M-8000 System Guide                           1.3  Memory Layout
+.sp 2
+.sh
+.tc    1.3  Memory Layout 
+1.3  Memory Layout
+.pp
+The CP/M-8000 operating system can reside anywhere in memory.
+The location of CP/M-8000 is defined 
+during system generation.  Typically the system occupies a
+segment which is logically separated from the TPA.
+.pp
+The TPA for non-segmented programs consists of one or two 64 Kbyte
+segments, one for program and one for data.  (Some programs 
+expect program and data to be mixed in one segment.  The segment
+in which such programs are run may be the same as or different
+from the segments for separated program and data.)  The TPA for
+segmented programs consists of up to 128 segments.
+
+The mapping from logical addresses (which consist of a 7-bit segment
+number and a 16-bit offset) into physical addresses is done by
+system-specific hardware, and the BIOS contains memory management
+operations to map addresses and copy blocks of memory.
+
+		=== GRAB DISCUSSION FROM ARTICLE??? ===
+
+.nf
+.sp 2
+.in 10
+	     === NEED MEMORY FIGURE FROM ARTICLE ===
+.sp
+.sh
+Figure 1-2.  Typical CP/M-8000 Memory Layout 
+.in 0
+.sp 2
+.fi
+.tc    1.4  Console Command Processor
+.sh
+1.4  Console Command Processor (CCP)
+.qs
+.he CP/M 8000 System Guide              1.4  Console Command Processor 
+.ix CCP
+.pp
+The Console Command Processor, (CCP) provides the user interface to
+CP/M-8000.  It uses the BDOS to read user commands and load programs,
+and provides several built-in user commands.  It also provides
+parsing of command lines entered at the console.   
+.ix user interface
+.ix built-in user commands
+.ix parsing, command lines
+.bp
+.tc    Basic Disk Operating System (BDOS)
+.sh
+1.5  Basic Disk Operating System (BDOS)
+.he CP/M 8000-System Guide            1.5  Basic Disk Operating System
+.pp
+The Basic Disk Operating System (BDOS) provides operating system services to
+applications programs and to the CCP.  These include character I/O,
+disk file I/O (the BDOS disk I/O operations comprise the CP/M-8000 file
+system), program loading, and others.  
+.ix BDOS
+.ix applications programs
+.ix I/O character
+.ix I/O, disk file
+.ix BIOS
+.ix interface, hardware
+.sp 2
+.tc    Basic I/O System (BIOS)
+.sh
+1.6  Basic I/O System (BIOS)
+.he CP/M 8000 Operating System            1.6  Basic I/O System (BIOS)  
+.pp
+The Basic Input Output System (BIOS) is the interface between CP/M-8000 and its
+hardware environment.  All physical input and output is done by the
+BIOS.  It includes all physical device drivers, tables defining disk
+characteristics, and other hardware specific functions and tables.  The 
+CCP and BDOS do not change for different hardware environments because
+all hardware dependencies have been concentrated in the BIOS.  Each hardware 
+configuration needs its own BIOS.  Section 4 describes the BIOS functions in 
+detail.  Section 5 discusses how to write a custom BIOS.  Sample BIOSes are 
+presented in the appendixes. 
+.sp 2
+.tc    I/O Devices
+.sh
+1.7  I/O Devices
+.he CP/M 8000 Operating System                        1.7  I/O Devices
+.pp
+CP/M-8000 recognizes two basic types of I/O devices:
+character devices and disk drives.  Character devices are serial devices that 
+handle one character at a time.  Disk devices handle data in units of 128 
+bytes, called sectors, and provide a large number of sectors which can be 
+accessed in random, nonsequential, order.  In fact, real systems might have 
+devices with characteristics different from these.  It is the BIOS's 
+responsibility to resolve differences between the logical device models and 
+the actual physical devices.
+.ix I/O devices, character
+.ix I/O divices, disk drives
+.ix sector
+.ix divice models, logical
+.sp 2
+.tc         1.7.1  Character Devices
+.sh
+1.7.1  Character Devices
+.pp
+Character devices are input output devices which accept or supply
+streams of ASCII characters to the computer.  Typical character devices are
+consoles, printers, and modems.  In CP/M-8000 operations on character devices
+are done one character at a time.  A character input device sends ASCII
+CTRL-Z (1AH) to indicate end-of-file.
+.ix character devices
+.ix ASCII character
+.ix CTRL-Z (1AH)
+.ix end-of-file
+.ix sectors, 128-byte
+.sp 2
+.tc         1.7.2  Character Devices
+.sh
+1.7.2  Character Devices
+.qs
+.pp
+Disk devices are used for file storage.  They are organized into sectors and 
+tracks.  Each sector contains 128 bytes of data.  (If sector sizes other than
+128 bytes are used on the actual disk, then the BIOS must do a 
+logical-to-physical mapping to simulate 128-byte sectors to the rest of the 
+system.)
+All disk I/O in CP/M-8000 is done in one-sector units.  A track is a group of
+sectors.  The number of sectors on a track is a constant depending on the
+particular device.  (The characteristics of a disk device are specified in
+the  Disk  Parameter  Block for  that  device.  See Section 5.)
+
+To locate a particular sector, the disk, track number,
+and sector number must all be specified.
+.ix disk devices
+.ix file storage
+.ix mopping, logical-to-physical
+.ix track
+.sp 2
+.tc    1.8  System Generation and Cold Start Operation
+.sh
+1.8  System Generation and Cold Start Operation
+.pp
+Generating a CP/M-8000 system is done by linking together the CCP, BDOS, and
+BIOS to create a file called CPM.SYS, which is the operating system.
+Section 2 discusses how to create CPM.SYS.  CPM.SYS is brought into memory
+by a bootstrap loader which will typically reside on the first two tracks
+of a system disk.  (The term system disk as used here simply means a disk
+with the file CPM.SYS and a bootstrap loader.)  Creation of a bootstrap loader
+is discussed in Section 3.
+
+		=== WORRY ABOUT THIS ===
+.ix track
+.ix CCP
+.ix BDOS
+.ix BIOS
+.ix disk
+.ix bootstrap loader
+.ix system disk
+.ix CPM.SYS
+.ix system generation
+.ix cold start
+.sp 2
+.ce
+End of Section 1
+.nx two