
>>>>>>>>>>>>>>>>>>>>> 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
	...

++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
