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Text of the page (random words):
number as built in commands 50 cp m 3 allows the user to abbreviate the built in commands 51 transient commands in cp m 3 include copysys date device dump ed get help hexcom initdir link mac pip put rmac set setdef show sid submit and xref 51 basic disk operating system edit the basic disk operating system 13 12 or bdos 13 12 provided access to such operations as opening a file output to the console or printing application programs would load processor registers with a function code for the operation and addresses for parameters or memory buffers and call a fixed address in memory since the address was the same independent of the amount of memory in the system application programs would run the same way for any type or configuration of hardware basic input output system edit cp m advertisement in the 11 december 1978 issue of infoworld magazine the basic input output system or bios 13 12 provided the lowest level functions required by the operating system these included reading or writing single characters to the system console and reading or writing a sector of data from the disk the bdos handled some of the buffering of data from the diskette but before cp m 3 0 it assumed a disk sector size fixed at 128 bytes as used on single density 8 inch floppy disks since most 5 25 inch disk formats used larger sectors the blocking and deblocking and the management of a disk buffer area was handled by model specific code in the bios customization was required because hardware choices were not constrained by compatibility with any one popular standard for example some manufacturers used a separate computer terminal while others designed a built in integrated video display system serial ports for printers and modems could use different types of uart chips and port addresses were not fixed some machines used memory mapped i o instead of the 8080 i o address space all of these variations in the hardware were concealed from other modules of the system by use of the bios which used standard entry points for the services required to run cp m such as character i o or accessing a disk block since support for serial communication to a modem was very rudimentary in the bios or may have been absent altogether it was common practice for cp m programs that used modems to have a user installed overlay containing all the code required to access a particular machine s serial port applications edit distribution 5 1 4 inch diskettes and packaging for the last version version 4 of wordstar word processing program released for 8 bit cp m wordstar one of the first widely used word processors and dbase an early and popular database program for microcomputers were originally written for cp m two early outliners kamas knowledge and mind amplification system and its cut down successor out think without programming facilities and retooled for 8080 v20 compatibility were also written for cp m though later rewritten for ms dos turbo pascal the ancestor of borland delphi and multiplan the ancestor of microsoft excel also debuted on cp m before ms dos versions became available visicalc the first ever spreadsheet program was made available for cp m another company sorcim created its supercalc spreadsheet for cp m which would go on to become the market leader and de facto standard on cp m supercalc would go on to be a competitor in the spreadsheet market in the ms dos world autocad a cad application from autodesk debuted on cp m a host of compilers and interpreters for popular programming languages of the time such as basic borland s turbo pascal fortran and even pl i 52 were available among them several of the earliest microsoft products cp m software often came with installers that adapted it to a wide variety of computers 53 the source code for basic programs was easily accessible and most forms of copy protection were ineffective on the operating system 54 a kaypro ii owner for example would obtain software on xerox 820 format then copy it to and run it from kaypro format disks 55 the lack of standardized graphics support limited video games but various character and text based games were ported such as telengard 56 gorillas 57 hamurabi lunar lander along with early interactive fiction including the zork series and colossal cave adventure text adventure specialist infocom was one of the few publishers to consistently release their games in cp m format lifeboat associates started collecting and distributing user written free software one of the first was xmodem which allowed reliable file transfers via modem and phone line another program native to cp m was the outline processor kamas citation needed transient program area edit the read write memory between address 0100 hexadecimal and the lowest address of the bdos was the transient program area tpa available for cp m application programs although all z80 and 8080 processors could address 64 kilobytes of memory the amount available for application programs could vary depending on the design of the particular computer some computers used large parts of the address space for such things as bios roms or video display memory as a result some systems had more tpa memory available than others bank switching was a common technique that allowed systems to have a large tpa while switching out rom or video memory space as needed cp m 3 0 allowed parts of the bdos to be in bank switched memory as well debugging application edit cp m came with a dynamic debugging tool nicknamed ddt after the insecticide i e a bug killer which allowed memory and program modules to be examined and manipulated and allowed a program to be executed one step at a time 58 59 60 resident programs edit cp m originally did not support the equivalent of terminate and stay resident tsr programs as under dos programmers could write software that could intercept certain operating system calls and extend or alter their functionality using this capability programmers developed and sold auxiliary desk accessory programs such as smartkey a keyboard utility to assign any string of bytes to any key 61 cp m 3 however added support for dynamically loadable resident system extensions rsx 50 17 a so called null command file could be used to allow ccp to load an rsx without a transient program 50 17 similar solutions like rsms for resident system modules were also retrofitted to cp m 2 2 systems by third parties 62 63 64 software installation edit although cp m provided some hardware abstraction to standardize the interface to disk i o or console i o application programs still typically required installation to make use of all the features of such equipment as printers and terminals often these were controlled by escape sequences which had to be altered for different devices for example the escape sequence to select bold face on a printer would have differed among manufacturers and sometimes among models within a manufacturer s range this procedure was not defined by the operating system a user would typically run an installation program that would either allow selection from a range of devices or else allow feature by feature editing of the escape sequences required to access a function this had to be repeated for each application program since there was no central operating system service provided for these devices the initialization codes for each model of printer had to be written into the application to use a program such as wordstar with more than one printer say a fast dot matrix printer or a slower but presentation quality daisy wheel printer a separate version of wordstar had to be prepared and one had to load the wordstar version that corresponded to the printer selected and exiting and reloading to change printers disk formats edit ibm system 34 and ibm 3740 s single density single sided format is cp m s standard 8 inch floppy disk format no standard 5 25 inch cp m disk format exists with kaypro morrow designs osborne and others each using their own 65 21 66 infoworld estimated in september 1981 that about two dozen formats were popular enough that software creators had to consider them to reach the broadest possible market 19 jrt pascal for example provided versions on 5 25 inch disk for north star osborne apple heath hard sector and soft sector and superbrain and one 8 inch version 67 ellis computing also offered its software for both heath formats and 16 other 5 25 inch formats including two different trs 80 cp m modifications 68 certain disk formats were more popular than others most software was available in the xerox 820 format and other computers such as the kaypro ii were compatible with it 55 69 no single manufacturer however prevailed in the 5 25 inch era of cp m use and disk formats were often not portable between hardware manufacturers a software manufacturer had to prepare a separate version of the program for each brand of hardware on which it was to run with some manufacturers kaypro is an example there was not even standardization across the company s different models because of this situation disk format translation programs which allowed a machine to read many different formats became popular and reduced the confusion as did programs like kermit which allowed transfer of data and programs from one machine to another using the serial ports that most cp m machines had various formats were used depending on the characteristics of particular systems and to some degree the choices of the designers cp m supported options to control the size of reserved and directory areas on the disk and the mapping between logical disk sectors as seen by cp m programs and physical sectors as allocated on the disk there were many ways to customize these parameters for every system 70 but once they had been set no standardized way existed for a system to load parameters from a disk formatted on another system the degree of portability between different cp m machines depended on the type of disk drive and controller used since many different floppy types existed in the cp m era in both 8 inch and 5 25 inch format disks could be hard or soft sectored single or double density single or double sided 35 track 40 track 77 track or 80 track and the sector layout size and interleave could vary widely as well although translation programs could allow the user to read disk types from different machines the drive type and controller were also factors by 1982 soft sector single sided 40 track 5 25 inch disks had become the most popular format to distribute cp m software on as they were used by the most common consumer level machines of that time such as the apple ii trs 80 osborne 1 kaypro ii and ibm pc a translation program allowed the user to read any disks on his machine that had a similar format for example the kaypro ii could read trs 80 osborne ibm pc and epson disks other disk types such as 80 track or hard sectored were completely impossible to read the first half of double sided disks like those of the epson qx 10 could be read because cp m accessed disk tracks sequentially with track 0 being the first outermost track of side 1 and track 79 on a 40 track disk being the last innermost track of side 2 apple ii users were unable to use anything but apple s gcr format and so had to obtain cp m software on apple format disks or else transfer it via serial link the fragmented cp m market requiring distributors either to stock multiple formats of disks or to invest in multiformat duplication equipment compared with the more standardized ibm pc disk formats was a contributing factor to the rapid obsolescence of cp m after 1981 one of the last notable cp m capable machines to appear was the commodore 128 in 1985 which had a z80 for cp m support in addition to its native mode using a 6502 derivative cpu using cp m required either a 1571 or 1581 disk drive which could read soft sector 40 track mfm format disks the first computer to use a 3 5 inch floppy drive the sony smc 70 71 ran cp m 2 2 the commodore 128 bondwell 2 laptop micromint ciarcia sb 180 72 msx and trs 80 model 4 running montezuma cp m 2 2 also supported the use of cp m with 3 5 inch floppy disks cp am applied engineering s version of cp m for the apple ii also supported 3 5 inch disks as well ram disks on ram cards compatible with the apple ii memory expansion card 73 the amstrad pcw ran cp m using 3 inch floppy drives at first and later switched to the 3 5 inch drives file system edit file names were specified as a string of up to eight characters followed by a period followed by a file name extension of up to three characters 8 3 filename format the extension usually identified the type of the file for example com indicated an executable program file and txt indicated a file containing ascii text characters in filenames entered at the command prompt were converted to upper case but this was not enforced by the operating system programs mbasic is a notable example were able to create filenames containing lower case letters which then could not easily be referenced at the command line each disk drive was identified by a drive letter for example drive a and drive b to refer to a file on a specific drive the drive letter was prefixed to the file name separated by a colon e g a file txt with no drive letter prefixed access was to files on the current default drive 74 file size was specified as the number of 128 byte records directly corresponding to disk sectors on 8 inch drives occupied by a file on the disk there was no generally supported way of specifying byte exact file sizes the current size of a file was maintained in the file s file control block fcb by the operating system since many application programs such as text editors prefer to deal with files as sequences of characters rather than as sequences of records by convention text files were terminated with a control z character ascii sub hexadecimal 1a determining the end of a text file therefore involved examining the last record of the file to locate the terminating control z this also meant that inserting a control z character into the middle of a file usually had the effect of truncating the text contents of the file with the advent of larger removable and fixed disk drives disk de blocking formulas were employed which resulted in more disk blocks per logical file allocation block while this allowed for larger file sizes it also meant that the smallest file which could be allocated increased in size from 1 kb on single density drives to 2 kb on double density drives and so on up to 32 kb for a file containing only a single byte this made for inefficient use of disk space if the disk contained a large number of small files file modification time stamps were not supported in releases up to cp m 2 2 but were an optional feature in mp m and cp m 3 0 17 cp m 2 2 had no subdirectories in the file structure but provided 16 numbered user areas to organize files on a disk to change user one had to simply type user x at the command prompt x bein...
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