CP/M

home *** CD-ROM | disk | FTP | other *** search

/ CP/M / CPM_CDROM.iso / cpm / news / cpmnet81.apr < prev next >

Wrap

Text File | 1994-07-13 | 27.6 KB | 737 lines

>>>>>>>>>>>>>>>>>>>>> CP/M-Net News <<<<<<<<<<<<<<<<<<<<<<<< ============================================================ Number 4 April, 1981 Volume 4, Issue 4 ============================================================ In This Issue ============= Programming Style Comparisons: Digital Research PL/I-80 and Microsoft BASIC by: Michael J. Karas Installing a Computer Bulletin Board Program by: Ben Bronson CP/M-Net "Tip-of-the-Month" Changes Required to XMODEM and TAG When Using MP/M by: Richard Rodman ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ >>>>> SPECIAL NOTICE <<<<< The following information was "down-loaded" from CBBS/Detroit on March 1, 1981. Please pass this around to any other CBBS, RCPM or ABBS that you use. "Sunday, 22 February 1981: A.B.S Computer Services in Olympia Washington was robbed and its owners, Henry and Laverne Rumburger, were killed." "The following is a partial list of items stolen with serial numbers. Note especially the Apple III! With few of them around, it might easier to find." "If you discover any of these items, contact Detective Jones, Olympia, Washington Police, (206)-753-8300." The stolen items are: Apple III (128k) #001065 Apple II (A2M030) #11892 Apple II (48k/A2SA) #152415 Apple II (48k) #95802 Disk II (with controller) #215227 BMC Monitor #65101709 Sony KB1216 television #503527 Centronics 737 printer #12349 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ Programming Style Comparisons: ============================== Digital Research PL/I-80 and Microsoft BASIC ============================================ by: Michael J. Karas I recently purchased a copy of a newly introduced applications programming development system that is a microprocessor oriented implementation of the PL/I programming language. This language, developed by Digital Research Inc., Pacific Grove, CA, is a powerful, structured compiler that is based upon the ANSII Standard PL/I Subset G. Gary Kildall of DRI has made this package compatible with the CP/M operating system for use on 8080/8085/Z80 types of microprocessors. The machine code developed by the compiler is also compatible with the above family of microprocessors. PL/I was originally developed by IBM as a large system language that was to be the last answer for programming languages in that it contained capabilities similar to FORTRAN, COBOL, ALGOL, and PASCAL. Over the years since its introduction PL/I has gained a reputation and a "following". The reputation has been that the compiler is huge and that the machine code modules produced are also huge. (ie many many bytes of memory are needed to run the compiler and the resulting programs). The "following" is a growing number of systems and applications programmers that have come to know the power of PL/I, ease of developing programs, degree of self documentation within programs, structure, and ease of maintaining programs. As the language gained popularity several manufacturers of minicomputers (including DEC) developed subset implementations of PL/I for their machines. Somewhere along the line a committee was formed to develop an ANSII standard PL/I subset to permit program transportability. Note that the idea of developing a PL/I subset was not to remove power or to limit capability of the language. Instead, much redundancy and feature overlap was removed to make the compiler requirements smaller and manageable in "minicomputer amounts of memory". About three years ago Gary Kildall of Digital Research saw that there would be a need and a market place for a good compiler type language for microprocessors. He decided that PL/I in a subset form would be the way to go. The results of his (and I'm sure also that of others at Digital) efforts is PL/I-80. This compiler, in my opinion, is the best thing to happen to the microprocessor field in several years. For those people who are serious applications programmers trying to develop sophisticated applications packages, the PL/I-80 system is the way to go. The reasons are multitude, some of which were mentioned in the previous paragraphs. In using PL/I-80 for several months now I have to say that the programs made in PL/I are blessed with the following advantages: a) Structure is inherent in the programming style. b) Programs are extremely self documenting. c) The compiler is fast!... and makes efficient code that also runs fast! d) Linkage of programs to assembly language or the CP/M operating system is really easy! e) The linkage capability includes an easy to use and powerful library and overlay generation capability. f) Data types included in the language are comprehensive. The PL/I-80 system has some small disadvantages that I'll mention just to set things straight for all those people who are hung up on other languages for various good reasons. Being a compiler the development time from coding to running code is much longer that an intrepreted language like BASIC. The program development time for the inexperienced PL/I programmer will generally be about 5 times as great as programming in BASIC. I have found that as I gained familiarity with the PL/I-80 features and had the use of a good screen mode video editor that program development time was some what less than twice that of BASIC. Also small programs seem to turn in to awful large .COM files. (small programs that do any I/O get large fast due to included device and file interface code.) The real efficiency of the generated code is felt when source code programs start to get up into the hundreds of lines. Small programs will typically be 60 to 100 lines and will generate 9 to 15 k bytes of machine code. Once large portions of the runtime library become utilized by the programs logical contents then each additional 20 to 30 lines of code may only add a portion of a "Kbyte" to the .COM file. Program checkout also tends to be harder if you desire to be a "seat of the pants" programmer. Small editing and logic mistakes cause a lot of time to be consumed in re-editing, re-compiling, and re-linking the program that is under development. Most BASIC programmers I know, including myself, tend to design and kludge programs right at the console due to immediate testing convenience offered by an interpretive language. A more serious programmer will tend to "design and conceptualize" a program ahead of the coding process. This makes a better, more structured, well thought out, and logically correct program. (For additional thoughts on design and conceptualization see Greg Williams editorial on page 6 of the March 1981 BYTE Magazine). When I make a PL/I program it tends to be developed by the latter process. The linking capability also allows programs to be developed in modules so that editing and manipulation of programs is done in small pieces. I often get asked the question, 'What is PL/I-80 like?'. In an attempt to answer that the remainder of this article will present a programming problem in both Microsoft BASIC and Digital Research PL/I-80. The aim is not to try to teach the reader how to write PL/I-80 programs or to demonstrate the full power of the language. I also want to stress that while this example can be implemented in either BASIC or PL/I-80, it should be noted that the latter language will generally provide a much better vehicle for implementing complex algorithms into a program due to the available language features and constructs. Obviously this cannot be demonstrated in a short article as this. The following examples are meant primarily to show one simple method of solving the same problem in two different computer languages. The comparison to BASIC was selected due to the fact that more readers probably know BASIC than any other language. This will permit the most enjoyable contrast of programming styles for those readers that are just now going to get their first glimpse of PL/I-80. The example programs are both designed to perform exactly the same function. The idea is to read a name/address/telephone number file in sequence. The data is then formatted to list the names and addresses in a format compatible with mailing labels on the printer. As each name is printed on its label, the name and telephone number are listed on the console. This example is designed for demonstration purposes only and may not represent an efficient or feasible implementation of the above name and address algorithm. The input data to the program is expected to exist in a file named "NAMES.DAT" on the default CP/M disk unit. The demo format for this file and some test records are shown below. Note that the data may have been formatted into these records by another program or through use of an editor. Also the field length is only typical and may be impractical in a real processing application. Field identification is as follows: last name, 8 bytes first name, 8 bytes middle initial, 1 byte address, 20 bytes city, 11 bytes state, 2 bytes zip code, 5 bytes phone number, 10 bytes Records are terminated with carriage return and line feed pairs. EXAMPLE INPUT DATA ------------------ KARAS MICHAEL J2468 HANSEN CT SIMI VALLEYCA930658055277922 SMITH KELLY S3055 WACO AVE SIMI VALLEYCA930638055270518 JOHNSON JACOB B2793 ANDREW COURT MANKADO MN567056123424469 ERICKSONSHIELA P454 B UNIVERSITY AVEFARGO ND581024154435523 WILLIAMSDALE F35912 CIRCLE MTN DR DAVENPORT IW590342179657451 HANSEN MICHAEL H2486 KARAS CT SIMI VALLEYCA930658055279355 KARAS HANSEN J8324 MICHAEL CT SIMI VALLEYCA930658055277922 NIXON GERALD R9355 KENNEDY BRIDGE OVER RIVER MS204312225551212 PAULSON DEBBI Q6699 HOLLOW TREE RD ROLLING LOGIL569433984535551 ABUSE VERBAL T23 BELOW NOSE FACE CITY NY432216589412257 PRETTY BOY M523 TOO SHORT CT BUMMER HILLKS582344325673349 The following program listing presents a PL/I-80 implementation of a program to read the above data and print the console list and the mail labels at the printer. Observation of the program structure and the various PL/I-80 constructs is left for the reader. /****************************************************************** A SHORT MAILING LABEL PRINTING PROGRAM IN PL/1-80 *****************************************************************/ maillab: procedure options(main); dcl /* declare all variables */ database file, syslist file, /* printer output name */ nulstr char(1) varying, 1 record, /* a structure for data */ 2 lastname char(8), 2 firstname char(8), 2 midinit char(1), 2 address char(20), 2 city char(11), 2 state char(2), 2 zip_code char(5), 2 phone_num char(10), 2 filler char(2), /* cr-lf filler from record */ 1 phone_format based(p),/* overlay template for phone # */ 2 area char(3), 2 prefix char(3), 2 line char(4), p pointer; open file(database) input record sequential title('names.dat'); open file(syslist) output stream print title('$lst'); /* setup what to do if we try to read the file and there is no more data */ on endfile(database) begin; close file(database); put file(syslist) skip; stop; end; /* tell operator to put mail labels into printer */ put edit('Put mail labels into printer.', 'Type "GO" when ready....') (skip(3),a,skip,a); get list(nulstr); /* set address pointer for phone format overlay template */ p=addr(record.phone_num); /* read data into structure and then print the mail labels */ do while('1'b); /* a forever loop!? */ read file(database) into(record); /* put names and phone numbers to console */ put skip edit(strip(firstname),' ', strip(lastname),' (', area,') ',prefix,'-',line) (3(a),col(30),6(a)); /* print names to printer on mail labels */ put file(syslist) edit(strip(firstname),midinit, '.',strip(lastname), strip(address),strip(city), state,zip_code) (skip(3),a,x(1),a,a,x(1),a,skip,a, skip,3(a,x(2))); end; /* function routine to return a string of varying length based upon input string with all trailing blanks removed */ strip: proc(string) returns(char(50) varying); dcl string char(50) varying, i,j bin fixed(15); i=0; do i=0 repeat (i+1) while(substr(string,(length(string)-i),1)=' '); end; string=substr(string,1,(length(string)-i)); return (string); end strip; end maillab; /* end of pl/i program */ The following listing shows a simple Microsoft BASIC program to perform the same function of printing the console listing and mail labels upon the printer. Once again the program analysis is left to the reader. Note that the logical program structure of the BASIC program is kept nearly the same as the previous PL/I-80 program to facilitate program comparisons. 10 REM 20 REM A SHORT MAILING LABEL PROGRAM IN MBASIC 30 REM 40 REM 50 REM TELL OPERATOR TO PUT LABELS INTO PRINTER 60 REM 70 PRINT:PRINT:PRINT 80 PRINT "Put mail labels into printer." 90 INPUT "Type 'GO' when ready....",NUL$ 100 OPEN "I",#1,"NAMES.DAT" 110 REM 120 REM SETUP FOR END OF FILE EXIT 130 REM 140 IF EOF(1)<0 THEN 470 150 REM 160 REM READ FILE RECORD AND FORMAT DATA 170 REM 180 LINE INPUT #1,REC$ 190 STRIP$=MID$(REC$,1,8) 200 GOSUB 530 210 LN$=STRIP$ 220 STRIP$=MID$(REC$,9,8) 230 GOSUB 530 240 FNM$=STRIP$ 250 MI$=MID$(REC$,17,1) 260 STRIP$=MID$(REC$,18,20) 270 GOSUB 530 280 AD$=STRIP$ 290 STRIP$=MID$(REC$,38,11) 300 GOSUB 530 310 CTY$=STRIP$ 320 ST$=MID$(REC$,49,2) 330 ZP$=MID$(REC$,51,5) 340 PH$=" ("+MID$(REC$,56,3)+") "+MID$(REC$,59,3)+"-"+MID$(REC$,62,4) 350 REM 360 REM PRINT NAME AND PHONE NUMBERS TO CONSOLE 370 REM 380 PRINT FNM$;" ";LN$;TAB( 30);PH$ 390 REM 400 REM PRINT NAMES ON LABELS AT PRINTER 410 REM 420 LPRINT:LPRINT 430 LPRINT FNM$;" ";MI$;". ";LN$ 440 LPRINT AD$ 450 LPRINT CTY$;" ";ST$;" ";ZP$ 460 GOTO 140 470 CLOSE 1 480 SYSTEM 490 END 500 REM 510 REM SUBROUTINE TO STRIP EXCESS BLANKS OFF THE END OF A STRING 520 REM 530 IF MID$(STRIP$,LEN(STRIP$),1)<>" " THEN RETURN 540 STRIP$=MID$(STRIP$,1,LEN(STRIP$)-1) 550 GOTO 530 If either of the above programs is run the output at the console appears as follows. <cr> indicates operator data entry and carriage return key depression. CONSOLE OUTPUT FROM PROGRAM --------------------------- Put mail labels into printer. Type 'GO' when ready....GO<cr> MICHAEL KARAS (805) 527-7922 KELLY SMITH (805) 527-0518 JACOB JOHNSON (612) 342-4469 SHIELA ERICKSON (415) 443-5523 DALE WILLIAMS (217) 965-7451 MICHAEL HANSEN (805) 527-9355 HANSEN KARAS (805) 527-7922 GERALD NIXON (222) 555-1212 DEBBI PAULSON (398) 453-5551 VERBAL ABUSE (658) 941-2257 BOY PRETTY (432) 567-3349 A> The following listing shows the printer output from either program. Only a portion of the listing is shown to give the idea without wasting too much paper. PRINTER OUTPUT -------------- MICHAEL J. KARAS 2468 HANSEN CT SIMI VALLEY CA 93065 KELLY S. SMITH 3055 WACO AVE SIMI VALLEY CA 93063 JACOB B. JOHNSON 2793 ANDREW COURT MANKADO MN 56705 SHIELA P. ERICKSON 454 B UNIVERSITY AVE FARGO ND 58102 DALE F. WILLIAMS 35912 CIRCLE MTN DR DAVENPORT IW 59034 MICHAEL H. HANSEN 2486 KARAS CT SIMI VALLEY CA 93065 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ Installing a Computer Bulletin Board Program ============================================ By: Ben Bronson If you want to put up a bulletin board or a program exchange system that runs under CP/M (and if you don't want to write all your own software from scratch) you have two choices: Ward Christensen's and Randy Suess's assembly- language CBBS and the BASIC-language RBBS written by Howard Moulton, Bruce Ratoff, Ron Fowler, Tim Nicholas and others. The Real CBBS ------------- CBBS is the daddy of all bulletin board programs for micro- computers and as such has been imitated to some extent by all other public-domain and commercial BBS software. It is also an excellent program: fast, compact, and flexible. One of its best features is its sophisticated message editing capability. However, as its authors tell the would-be system operator quite plainly, installing it (not to mention modifying it) does require a good knowledge of assembly language. CBBS is written as a whole set of modules that have to be configured, then linked, and finally maintained with another set of programs. If you are good at assembly language, you should certainly choose it over RBBS. The cost is negligible in terms of what you get -- Send a check for $50 made out to Randy Suess to: CBBS, 5219 W Warwick, Chicago, Ill. 60641. You will receive a copy of the CBBS source program and files on 2 CP/M format soft sectored 8" floppy disks. MINICBBS -------- If you are only moderately familiar with assembler and want to run a system dedicated to software downloading rather than message interchange, there is one intermediate alternative that should be mentioned: Keith Petersen's stripped-down version called MINICBBS, which runs as a COM file on a CP/M system to which (as is normal with program downloading or RCPM setups) the caller has access. MINICBBS can be obtained in already assembled form from any of the SYSOPS (Keith himself, Dave Hardy, Calamity Cliffs or Dave Moritz) who use it, but (as CBBS is copyrighted and as MINICBBS needs several of the auxiliary and maintenance programs supplied on the CBBS distribution disks) they will only release it to those who have bought CBBS. MINICBBS retains the good message editingfeatures of its parent program and occupies only about l0K of disk space. It is a good deal easier to get up and running than the full CBBS. The only disadvantages of MINICBBS are (1) that making modifications requires greater familiarity with assembler and (2) that its method of storing new messages makes keeping these private from other users a bit complicated. The programs to do this are well worked out and in the public domain (for example, SECURITY.ASM and TAG2.ASM), but most MINICBBS sysops still find it necessary to keep the program and its messages in a very high user area and to move everything back down whenever they want to do some purging and editing. RBBS, Etc. ---------- The main (and only) alternative to the CBBS series is RBBS or its two RCPM-specialized descendants, ENTERBBS and MINIRBBS. The RBBS programs have several shortcomings. In their current form they have inferior message editing features. They are impossibly slow when run as BAS files under MBASIC. And when compiled with BASCOM (which makes them almost as fast as CBBS or sometimes even as fast), they are bulky. A compiled RBBS occupies 34K of disk space and RAM, and a compiled MINIRBBS needs 30K all by itself, compared with the 10K used by MINICBBS. While most people have enough RAM so that size in memory is not a problem, the RBBS series performs noticeably worse on systems with slow disk drives. On the other hand, RBBS has a single great advantage: it is a lot easier to install. If you have a very modest knowledge of BASIC and own or have access to BASCOM, you can get a RBBS system up and running in a single evening, while installing CBBS takes several days for a crack assembly- language programmer. To the RCPM operator its use of a MBASIC-type sequential message file is also an advantage -- access to messages can be controlled simply by declaring the MESSAGES file a $SYS file, and can easily be protected from XMODEMing by using TAG2.COM. RBBS is essentially self-explanatory, but a few notes might ease the installation process even further. Briefly, one becomes an RBBS SYSOP like this: Installing RBBS --------------- (1) Get RBSUTL22.BAS (or ASC) and RBBS24.BAS (and later, ENTBBS24 & MINBBS24.BAS as well) from a local RCPM system. As indicated earlier, you will also need to have a version of BYE (PMMIBY63, BYE65 and BYE67 all can load a COM file automatically after bringing themselves up when the telephone rings, so choose one of those -- the COM file in question will of course be RBBS.COM). (2) Try the program with MBASIC in interpreter mode. Just type MBASIC RBBS24 and see what happens. (3) Look at the disk directory after you have exited back to CP/M. You'll notice that several new files have been created: MESSAGES, CALLERS, USERS, COUNTERS, SUMMARY, LASTCALR and (if you have left yourself a comment) COMMENTS. These are 7/11 of the auxiliary files that a full-fledged RBBS can use, and 7/7 of those it absolutely has to use. (4) Now use an editor (or a word processor that does not put queer control characters in the file--WordStar in non- document mode works fine) to write four brief text files. Put amything you want into three of them, and call them INFO, BULLETIN and NEWCOM. Just that. Filenames without filetypes. The fourth file, PWDS, should contain only three words separated by commas: HONDURAS,BANANA,NOPASS These are the P1$, P2$ and P3$ you will see referred to in the early parts of the source code. "HONDURAS" and "BANANA" can be replaced with whatever you like; those are passwords for you, the SYSOP to use for quick entry and message- killing authority within the system. "NOPASS" is what you put in if the system is to be for unrestricted public use. Anything else here will become the access password for all users. Now return to CP/M. (5) Try the MBASIC RBBS routine again several times. Sign in with the same name, then with different names. Notice which text files are printed where when the name is new and when it is one the program already knows. Try signing yourself in with the first name SYSOP and the second name anything but BANANA or whatever your P2$ is. When you have had enough of this, (6) TYPE all the files with one-word names to see what they look like. If you look at them with an editor you'll notice that the ones created by the program rather than you all have fixed-length lines. Use the editor to put asterisks in front of a couple of the names you've invented that are already in the USERS file. Make sure you don't inadvertently make the lines with asterisks longer than the others, and put the asterisks at the very beginning of the line. (7) Go back to CP/M and do MBASIC RBBS24. Sign in with one of the names you have marked with an asterisk and see what happens. Play around with passwords a bit more. By now you should understand most of the program's tricks. (8) So go into RBBS24 (again with an editor or word processor that does not create MBASIC-incompatible conttol characters) and personalize the various messages that appear in quotation marks. Exit. Test with MBASIC. Try all combinations of commands and make sure they still work. Kill a couple of messages. Notice that you can kill the passworded ones if you're the SYSOP. (9) Next try RBSUTL22.BAS. Run it with MBASIC. Look at the menu and do what it tells you to do. Purge the file of killed messages. Remember to rebuild the SUMMARY file. Exit. Look at the directory and what has happened to the MESSAGES and other files. Now you know how to maintain an RBBS system. (10) And then compile. You'll need about 50-52K of memory to hold both BASCOM and RBBS. If you don't have that much, prevail on a friend or a local SYSOP (who is likely to be delighted at the idea of a new system that'll take some of the pressure off his) to compile it for you. Use the /X switch (check the manual for why if you're curious). Load with L80 with the /E and /N switches. And presto. You have a file called RBBS24.COM. Do the same with RBSUTL22. (11) Run it. Make sure it works as advertised. Notice that it picks up all the files created while you were trying the program out with MBASIC and treats those files as its own. Rewrite the INFO, BULLETIN and NEWCOM files so that they contain appriate messages. Test RBSUTL22. Note that it runs a good deal faster in compiled form. (12) Last, assemble BYE with the filename of whatever you have called RBBS24.COM (that'll work fine) in the appropriate place. Load it so that it too becomes a COM file. (13) Type BYE. Notice that it responds "COM FILE LOADED". Wait for the telephone to ring. (14) With any luck at all, you will find that you are now the proud proprietor of a Computer Bulletin Board. The rest is up to you. You'll have to decide whether you want public or passworded access, emphasis on messages or programs, and that sort of thing. If you opt for a RCPM or program down-loading function, RBBS will work quite nicely for that too, but you may care to try ENTBBS24 and MINBBS24, which offer less temptation to people who want to use the system as primarily a message service. Once you've succeeded in getting RBBS up, ENTERBBS & MINIRBBS will be a piece of cake. ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ CP/M-Net "Tip-of-the-Month" =========================== Changes Required to XMODEM and TAG When Using MP/M ================================================== By: Richard Rodman Micro Research, Inc. 8303 Arlington Blvd Fairfax VA 22031 While the CP/M and MP/M manuals both say that the bits f1' thru 4' are user-definable, it so happens that under MP/M, a process with bit 7=1 on the first letter of its name cannot be broken with Control-C or output stopped with Control-S, et cetera. Therefore, f1' actually is not available to the user. For this reason, you must move the tag bit to f2' if you intend to run MP/M on a remote system utilizing XMODEM with "tagged" files (i.e. "tagged" to prevent file transfers of "distribution-protected" programs OUT of the remote MP/M system). I have included some relevant listing portions below, from TAG and XMODEM, to fix the problem. from TAG: pext: ... rrc ;bit 7=0 for R, 1 for S ani 80h mov b,a ;save mask lxi d,dfcb+2 ;point to f2 ldax d ;get it ani 7fh ;strip f2' ora b ;set bit if option was S stax d ;put it back dcx d dcx d ;Added one more ... call bdos nextfile: lda dfcb+2 ;get f2 rlc ;isolate f2' ani 1 ... from XMODEM: ;Check for distribution-protected file ; OPENOK LDA FCB+2 ;second CHAR OF FILE NAME ANI 80H ;CHECK BIT 7 JZ OPENOK2 ;IT WAS OFF, FILE CAN BE SENT ... ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++