SECTION 11
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11. Introduction to CP/M 3.0
11.1 WHAT CP/M 3.0 IS
CP/M is a product of Digital Research, Inc. The version of CP/M used on the Commodore 128 is CP/M Plus Version 3.0. In this chapter, CP/M is generally referred to as CP/M 3.0, or simply CP/M. This chapter summarizes CP/M on the Commodore 128. For detailed information on CP/M 3.0, follow the instructions on the coupon enclosed in the box in which the Commodore 128 is supplied.
CP/M 3.0 is a popular operating system for microcomputers. As an operating system, CP/M 3.0 manages and supervises your computer's resources, including memory and disk storage, the console (screen and keyboard), printer, and communication devices. CP/M 3.0 also manages information stored in disk files. CP/M 3.0 can copy files from a disk to your computer's memory, or to a peripheral device such as a printer. To do this, CP/M 3.0 places various programs in memory and executes them in response to commands you enter at your console. Once in memory, a program executes a set of steps that instruct your computer to perform a certain task.
You can use CP/M to create your own programs, or you can choose from the wide variety of available CP/M 3.0 application programs.
11.2 WHAT YOU NEED TO RUN CP/M 3.0
The general hardware requirements for CP/M 3.0 are a computer containing a Z80 microprocessor, a console consisting of a keyboard and a display screen, and at least one floppy disk drive. For CP/M 3.0 on the Commodore 128 Personal Computer, the Z80 microprocessor is built-in; the console consists of the full Commodore 128 keyboard, and an 80-column monitor; and the disk drive is the new Commodore 1571 fast disk drive. In addition, there is either one or two CP/M disks packed with the computer. If two CP/M disks are supplied, one contains the CP/M 3.0 system and an extensive HELP utility program, and the other contains a number of other utility programs. If one CP/M disk is supplied, the system and HELP utility are on one side of that disk and the utility programs are on the other.
Note: Although CP/M can be used with a 40-column monitor, the display is 80 column but with only 40 columns displayed at one time. To view all 80 columns of the display, you must scroll the screen horizontally by pressing the {ctrl} key and the appropriate cursor key ({crsr left} or {crsr right}).
11.3 WHAT IS ON YOUR CP/M 3.0 DISK
show b:
B: RW, Space 336k
A>dir [full]
Scanning Directory...
Sorting Directory...
Directory for Drive A: User 0
Name Bytes Recs Attributes Name Bytes Recs Attrib.
------------ ------ ------ ------------ ------------ ------ ------ --------
CCP .COM 4k 25 Dir RW CPM+ .SYS 23k 182 Dir RW
DIR .COM 15k 114 Dir RW FORMAT .COM 5k 35 Dir RW
HELP .COM 7k 56 Dir RW HELP .HLP 83k 664 Dir RW
KEYFIG .COM 10k 75 Dir RW KEYFIG .HLP 9k 72 Dir RW
PIP .COM 9k 68 Dir RW
Total Bytes = 165k Total Records = 1291 Files Found = 9
Total 1k Blocks = 165 Used/Max Dir Entries For Drive A: 15/ 64
A>dir b: [full]
Scanning Directory...
Sorting Directory...
Directory for Drive B: User 0
Name Bytes Recs Attributes Name Bytes Recs Attrib.
------------ ------ ------ ------------ ------------ ------ ------ --------
DATE .COM 8k 25 Dir RW DATEC .ASM 2k 5 Dir RW
DATEC .RSX 2k 3 Dir RW DEVICE .COM 16k 58 Dir RW
DIR .COM 30k 114 Dir RW DIRLBL .RSX 4k 12 Dir RW
DUMP .COM 2k 8 Dir RW ED .COM 20k 73 Dir RW
ERASE .COM 8k 29 Dir RW GENCOM .COM 30k 116 Dir RW
GET .COM 14k 51 Dir RW INITDIR .COM 64k 250 Dir RW
PATCH .COM 6k 19 Dir RW PIP .COM 18k 68 Dir RW
PUT .COM 14k 55 Dir RW RENAME .COM 6k 23 Dir RW
SAVE .COM 4k 14 Dir RW SET .COM 22k 81 Dir RW
SETDEF .COM 8k 32 Dir RW SHOW .COM 18k 66 Dir RW
SUBMIT .COM 12k 42 Dir RW TYPE .COM 6k 24 Dir RW
Total Bytes = 314k Total Records = 1168 Files Found = 22
Total 1k Blocks = 314 Used/Max Dir Entries For Drive A: 23/ 64
11.3.1 CP/M+.SYS
This is the main CP/M Plus system file. It contains all parts of the system that remain permanently resident in memory: the Basic Input/Output System (BIOS) which loads into the top of memory, the Basic Disk Operating System (BDOS) which loads into memory immediately below BIOS, and the System Parameters which load into the bottom page of memory.
11.3.2 CCP.COM
On booting CP/M the Console Command Processor (CCP) is loaded into memory immediately below the BDOS. The remaining memory, below CCP and above page 0, is known as the Transient Program Area (TPA) and is where applications are loaded to. CCP is the program which processes any input (usually entered from the keyboard) in response to the system prompt (A>). It contains 6 built-in commands (listed in Table 14-1), and also supports the 14 console editing commands (listed in Table 13-1).
Any word entered in response to the system prompt which is not one of the built-in commands is treated by CCP as a transient command, so CCP attempts to find and execute a file named as that word with the .COM extension. If it does not find such a file on the currently logged disk, it displays the word followed by a question mark then brings back the system prompt.
If more than one word is entered in response to the system prompt, all words after the first are treated as parameters to be passed to the transient command.
A language or application program is loaded and run by invoking it as if it was a command. All CP/M programs include a .COM file
11.3.3 .COM Files
The other .COM files all contain transient commands (listed in Table 14-2).
HELP.COM displays messages, held in HELP.HLP (whose extension indicates it is a data file, not a program file), about the C128 CP/M system and its commands. If you are not familiar with CP/M and have no other manuals or books about it, you may find it useful to print out any HELP you look at. Pressing {ctrl} and {p} CAUSES any screen output also to go to the printer: pressing {ctrl}{p} again turns off this facility.
Enter HELP for the list of subjects covered, or HELP C128_CP/M for information specific to this implementation. (The character in the middle of C128_CP/M is obtained by pressing the {left arrow} key at the top left of the keyboard.) If you are printing and do not want pauses after each screenful, then enter HELP C128_CP/M [NOPAGE].
11.3.4 Other Files
.ASM indicates an Assembler source file.
.RSX indicates a Resident System eXtension, which is a file automatically loaded by a command file as and when it is needed.
11.4 GETTING STARTED WITH CP/M 3.0
The following paragraphs tell you how to start or "boot" CP/M 3.0, how to enter and edit the command line, and how to make back-up copies of your CP/M 3.0 disks.
11.4.1 Loading or Booting CP/M 3.0
Loading or "booting" CP/M 3.0 means reading a copy of the operating system from your CP/M 3.0 System Disk into your computer's memory.
You can boot CP/M 3.0 in several ways. If your computer is off, you can boot CP/M by first turning on your disk drive and inserting the CP/M 3.0 system disk, and then turning on the computer. CP/M 3.0 then loads automatically. If you are already in C128 BASIC mode, you can boot CP/M 3.0 by inserting the CP/M system disk into the drive, typing the BASIC command BOOT and then pressing {return}. CP/M 3.0 then loads. In C128 mode, you can also boot CP/M by inserting the System Disk and pressing the {reset} button.
If you are in C64 mode, and you want to enter CP/M mode, first turn off the computer. The insert the CP/M System Disk into the drive and turn on the computer.
Caution: Always make sure that the disk is fully inserted in the drive before you close the drive door.
In CP/M 3.0 on the Commodore 128, the user has a 59K TPA (Transient Program Area), which is, in effect, user RAM.
11.4.2 The Opening CP/M Screen Display
After CP/M is loaded into memory, a message similar to the following is displayed on your screen:
![[ASCII IMAGE]](../c128sgimg/cpmscreen.gif)
An important part of the opening display is the following two-character message:
A>
This is the CP/M 3.0 system prompt. The system prompt tells you that CP/M is ready to read a command entered by you from your keyboard. The prompt also tells you that drive A is your default drive. This means that until you tell CP/M to do otherwise, it looks for program and data files on the disk in drive A. It also tells you that your are logged in as user 0, simply by the absence of any user number other than 0.
Note: In CP/M a single disk drive is identified as drive A. This is equivalent to unit 8, drive 0 in C128 and C64 modes. Usually, the maximum number of drives in CP/M is four. Additional drives are identified as drives B, C, etc.
11.5 THE COMMAND LINE
CP/M 3.0 performs tasks according to specific commands that your type at your keyboard. These Commands appear on the screen in what is called a command line. A CP/M 3.0 command line is composed of a command keyword and an optional command tail. The command keyword identifies a command (program) to be executed. The command tail can contain extra information for the command, such as a filename or parameters. The following example shows a command line.
A>DIR MYFILE
In this example, DIR is the command keyword and MYFILE is the command tail. To send the command line to CP/M 3.0 for processing, press the {return} key.
As you type characters at the keyboard, the appear on your screen. The cursor moves to the right as you type. If you make a typing error, press either the {inst/del} key or CTRL-H to move the cursor to the left and correct the error. CTRL is the abbreviation for the {ctrl} key. To specify a control character, hold down the {ctrl} key and press the appropriate letter key. (A list of control characters and their uses is given in Section 13.)
You can type the keyword and command tail in any combination of upper-case and lower-case letters. CP/M 3.0 interprets all letters in the command line as being upper case.
Generally, you must type a command line directly after the system prompt. However, CP/M 3.0 does allow spaces between the prompt and the command keyword.
11.5.1 Types of Commands
CP/M 3.0 recognizes two different types of commands: built-in commands and transient utility commands. Built-in commands execute programs that reside in memory as a part of the CP/M operating system. Built-in commands can be executed immediately. Transient utility commands are stored on disk as program files. They must be loaded from disk to perform their task. You can recognize transient utility program files when a directory is displayed on the screen, because their filenames are followed by a period (full stop) and COM (.COM). Section 14 presents lists of CP/M built-in and transient utility commands.
For transient utilities, CP/M 3.0 checks only the command keyword. Many utilities require unique command tails. If you include a command tail, CP/M 3.0 passes it to the utility without checking it. A command tail cannot contain more than 128 characters.
11.5.2 How CP/M Reads Command Lines
Use the DIR command to demonstrate how CP/M reads command lines. DIR, which is an abbreviation for directory, tells CP/M to display a directory of disk files on your screen. Type the DIR keyword after the system prompt, and press the {return} key:
A>DIR {return}
CP/M responds to this command by displaying the names of all the files that are stored on whatever disk is in drive A. For example, if the CP/M system disk is in the disk drive A, a list of filenames like this appears on your screen:
A: PIP COM:ED COM:CCP COM:HELP COM:HELP HLP A: DIR COM:CPM SYS
CP/M recognizes only correctly spelled command keywords. If you make a typing error and press {return} before correcting your mistake, CP/M 3.0 repeats or "echoes" the command line followed by a question mark. For example, suppose you mistype the DIR command, as in the following example:
A>DJR {return}
CP/M replies with:
DJR?
This tells you the CP/M cannot find a command keyword spelled DJR. To correct typing errors like this, you can use the {inst/del} key to delete the incorrect letters. Another way to delete characters is to hold down the {ctrl} key and press {h} to move the cursor to the left. CP/M provides a number of other control characters that help you edit command lines. Section 13 tells how to use the control characters to edit command lines and other information you enter at your console.
DIR accepts a filename as a command tail. You can use DIR with a filename to see if a specific file is on the disk. For example, to check that the file MYFILE is on your disk, type:
A>DIR MYFILE {return}
CP/M 3.0 performs this task by displaying either the name of the file you specify, or the message:
No File
Be sure you type at least one space after DIR to separate the command keyword from the command tail. If you do not, CP/M 3.0 responds as follows:
A>DIRMYFILE {return}
DIRMYFILE?
11.6 HOW TO COPY YOUR CP/M 3.0 DISK
Before doing anything else you should back-up your CP/M system disk. This can be done using either one or two disk drives. If using two disk drives these may be 1541s, 1571s, or one of each. The back-up disks can be new or used. You can either format new disks, or reformat used disks. To make back-ups use the FORMAT and PIP utility programs found on you CP/M system disk.
- Format the diskette using the FORMAT program, as either C128 single sided (if using a 1541) or C128 double sided (if using a 1571). (The C64 single sided option is for formatting disks compatible with the CP/M 2.2 package once sold for the Commodore 64.)
Enter the command FORMAT, select the required disk type with the {crsr down} key, press {return}, and follow the onscreen instructions. Press {y} (Yes) or {n} (No) in response to the 'Do you want to format another disk' question. - Use the Peripheral Interchange Program (PIP) - on the second surface of the original disk - to copy files. Enter PIP and the usual system prompt (A>) will be replaced by the PIP prompt (*).
If you have a single disk drive use drive A as the source drive and drive E as the destination drive. Drive E is referred to as a virtual drive - that is, it does not exist as an actual piece of hardware. Put the disk to be copied from in the drive and enter
E:=A:*.*
(You will be prompted each time the source disk and the destination disk have to be swopped.)
If you have two disk drives, put the source disk in drive A (which is device 8) and the newly formatted disk in drive B (device 9 - set by putting the left DIP switches on the back of the 1571 down while the drive is switched off) and enter
B:=A:*.*to copy all the files.
Your original CP/M disk is a flippy - i.e. recorded as 2 single sides, so it must be taken out of the drive and turned over to get at the second side. This is required for use in a 1541, which is a single sided drive. If you have a 1541 you should copy the 2 surfaces onto 2 separate disks. However, if you have a 1571 you will find it convenient to copy both surface onto a standard double sided disk: after copying the first side, turn over the original disk and copy the second side onto the same destination disk by again entering the copy instruction in response to the PIP prompt.
You may sometimes want to make disks that just have the system files on them. To do this use PIP to copy the files CPM+.SYS and CCP.COM to the newly formatted disk.
Note: Only disks that you intend to use to boot CP/M need these 2 files on them - putting them on other disks wastes space.
With a single drive, enter
E:=A:CPM+.SYSto copy the first file and then
E:=A:CCP.COMto copy the second file.
When you have finished PIP, press {return} to return from the PIP prompt to the system prompt.
A full description of PIP can be obtained by entering HELP PIP, HELP PIP_OPTIONS and HELP PIP_EXAMPLES.
11.7 LANGUAGES AND APPLICATION SOFTWARE
CP/M is just an operating system, that is a means to an end - not an end in itself. On its own it does not do anything useful. If you want to write your own programs you will need a language, either assembler or high level, in which to write them. If you want to play games or do business work you will need application programs.
11.7.1 What To Buy
Because CP/M has been implemented on almost every computer ever designed that used the Intel 8080 or the Zilog Z80 cpu, there is a very large amount of software available for running on CP/M systems. The most comprehensive catalogue of commercial software is the 'CP/M Software Finder' published for Digital Research by Que Corporation and available through good software retailers (ISBN 0-88-022-021-X). Since it is not convenient for the CP/M Users Group to supply its library on Commodore format disks, a selection of public domain CP/M software has been made available through the independent Commodore Products Users Group (ICPUG), for which membership application forms can be obtained by sending an s.a.e. to Membership Secretary, ICPUG, 30 Brancaster Rood, Newbury Park, Ilford, IG2 7EP, England.
CP/M normally uses Modified Frequency Modulation (MFM) ot record on disks. Commodore DOS normally uses Group Code Recording (GCR). The Commodore 1571 disk drive can read both, but the older 1541 can only read GCR. Off-the-shelf CP/M software packages only come as MFM disks. Even with MFM there are many different formats: the 1571 can read disks formatted for:
Epson QX10 |
(512 byte sectors, double sided, 10 sectors per track) |
IBM-8 SS (CP/M-86) |
(512 byte sectors, single sided, 8 sectors per track) |
IBM-8 DS (CP/M-86) |
(512 byte sectors, double sided, 8 sectors per track) |
IBM-9 SS (CP/M-86) |
(512 byte sectors, single sided, 9 sectors per track) |
IBM-9 DS (CP/M-86) |
(512 byte sectors, double sided, 9 sectors per track) |
KayPro II |
(512 byte sectors, single sided, 10 sectors per track) |
KayPro IV |
(512 byte sectors, double sided, 10 sectors per track) |
Osborne DD SS |
(1024 byte sectors, single sided, 5 sectors per track) |
Osborne DD DS |
(1024 byte sectors, single sided, 5 sectors per track) |
Therefore when buying CP/M software you must buy it on a disk in one of the above formats. Also, be aware that your C128 will run software written to run under either CP/M 2.2 or CP/M Plus (which is the newer name for what was originally known as version 3). However, CP/M-86 is the version of CP/M designed for use on 16-bit processors: CP/M-86 software will not run on your C128's 8-bit Z80 processor, although the 1571 drive will let you read CP/M-86 data files.
If you only have a 1541 disk drive you will have to get any software you buy transferred from MFM format to (Commodore) GCR format. Some software retailers may be willing to do this for you, but there will probably be a copying charge. Alternatively, you may find that your local ICPUG group provides facilities to do this at its meetings.
11.7.2 How To Install It on Your C128
Because there are so many different computers using the CP/M operating system, many CP/M programs have to be configured for the particular hardware on which they are to be used. The process of installing a program on your C128 involves setting parameters within the software. The program manual will describe how to install the program if this is required. Most programs provide a list of common terminals which they support. If ADM31 appears in this list, select it. If not, your will have to do a custom installation.
Listed below are the entries that should be made when running WINSTALL.COM (the installation program that is part of the Wordstar package). These also provide the information that will be needed for installing other programs, although not all packages ask the same questions.
Terminal name Commodore 128
Screen size
Screen height 24
Screen width 80
Cursor positioning
Function code sequence 1Bh 3Dh
Characters to be sent between line
number and column number none
Characters to be sent after line
number and column number none
Is the column number sent before
the line number? NO
What character is sent to the
terminal to signify line 1? 20h
What character is sent to the
terminal to signify column 1? 20h
What types of code are sent to
signify line and column numbers? Single byte BINARY value
Terminal start-up
Function code sequence 1Bh 59h 1Bh 1Bh 1Bh 60h
Terminal exit
Function code sequence none
Highlight-on
Function code sequence 1Bh 1Bh 1Bh 52h
Highlight-off
Function code sequence 1Bh 1Bh 1Bh 51h
Erase to End of Line 1Bh 54h
Delete Line 1Bh 52h
Insert Line 1Bh 45h
Does your terminal use last character
on screen as a scroll command? YES
Most Commodore printers require installation as a Standard Printer with NO Communications Protocol and Primary list device as the Printer Driver.
Note: The h against the numbers above indicate that they are hexadecimal numbers (using base 16 instead of the decimal base 10).
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