›(While  some  of  the following is old›that to some of   you,  there   is   a›possibility that   you     may    have›forgotten  some basics›--- PUN INTENDED---)›Reprinted from M.A.G.I.C.'s EXCELLENT›Newsletter, September 1990.›            Ye OLDE EDITORS› -=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-››                                      ›    Atari BASIC Programming Helps›By  Hawke,  Sysop  of  the  Nine Hells›Information  Exchange of Philadelphia,›(215) 785-2625››As  a  whole,  standard Atari BASIC is›not  the  best  programming  medium in›existence.   One of the major problems›stems   from  the  fact  that  it  was›created  too  many years ago.  Be that›as  it  may, new programmers are being›subjected  to  it  now, unnecessarily,›and  must  deal with a user unfriendly›language.  Inspired by a set of PASCAL›notes, I venture to write these helps,›so  that  BASIC  programmers can learn›from  my  experience,  as  well as the›Phoenix,  with  whom  I have consulted›about  this  text.   Any  questions or›comments are welcomed.  Contact myself›or  Phoenix through the above Bulletin›Board number.››The   following   sections  deal  with›POKE's, PEEK's, small machine language›routines, some program listings, BASIC›tricks, and other such nonsense.››ROUTINE  ONE:  (Three Lower case H's),›(INVERSE   asterisk),   (Capital   L),›(Capital V), (INVERSE Lower case D)››ROUTINE TWO:  (Lower case H), (INVERSE›Quote),  (Control  P), (SPACE), (Upper›case   V),  (INVERSE  lower  case  D),›(INVERSE  control A), (INVERSE capital›T),   (INVERSE   close   parenthesis),›(Control   ,),  (INVERSE  control  E),›(INVERSE capital U), (Control .)››(Ed.  note:   When typing in the above›routines, DON'T type in the commas.)››Section    One:    Machine    Language›Routines››Many  BASIC programmers are fearful of›using  machine language subroutines in›their  programs.   I  know  this to be›true,  because  I  was one of them.  I›have  since  gotten  over  that  fear,›after   collaboratively   writing  the›P-Net 4.5 BBS system with the Phoenix,›and have converted a few others.››If you have ever used Character Fonts,›made  with  any  number of font editor›programs  (Envision, SuperFont, etc.),›you  know  that  they  can  be used to›create  fancy text, graphics, or maps.›The problem with them is that one must›enter in 1,024 bytes, poke them into a›page  of  memory,  and then change the›register  holding  the  address of the›ROM  set  to  the  new set.  To do all›this  takes  a bit of time to do.  The›following  machine language subroutine›loads  in  a character set and adjusts›the register in seconds.››1            POKE           881,0:OPEN›#3,4,128,"D:SET.DAT":  POKE 884,0:POKE›885,112:POKE  888,0:  POKE  889,4:POKE›882,7›2  AA=USR(ADR("ROUTINE ONE"),48):CLOSE›#3:POKE 54277,4:POKE 756,112››* SET.DAT would be the font.››*  Poking  885,112  tells  the machine›which  page  of  memory  the redefined›character set will be stored in (since›a  character  set  MUST  start  at the›beginning of a page).››*  To  return  to  the ROM set, simply›POKE  756,224.   To  go  back  to  the›redefined font, POKE 756,112.›››The  next  machine  routine deals with›speedy    Disk   I/O.    Atari   BASIC›programmers  know that using the INPUT›and  GET  commands  with disk files is›SLOW,   especially  when  using  large›amounts   of   data.    The  following›machine   language  subroutine  solves›this  problem  by allowing you to read›an   entire   file   into   a  string,›virtually,  in  seconds.   This can be›useful when printing out text files or›editting machine language programs (by›string search, etc.).›› 900           CLOSE           #1:OPEN›#1,4,0,"D1:filename.ext"›1000  CE=INT(MEM/256):POKE 857,CE:POKE›856,MEM-256*CE:›BUF$(MEM)=" ":BOF=C1›1010  POKE 853,INT(ADR(BUF$)/256):POKE›852,›ADR(BUF$)-PEEK(853)*256›1020  DUM$="ROUTINE TWO":POKE 850,7:IF›USR(ADR(DUM$))=136›THEN BOF=C0›1030›X=PEEK(856)+256*PEEK(857):BUF$=BUF$(1,›):RETURN››* MEM is the amount of characters that›BUF$ is dimensioned to hold.››* In line 1000, the routine divides up›that  number  into  two numbers with a›formula   (16-bit  conversion).   This›tells   the   subroutine  the  maximum›length  the  string can hold.  It then›sets  the last character in BUF$ equal›to  a character, thus, it defines BUF$›as being full.››*   Line   1010  divides  the  address›(starting  location)  of  BUF$  by the›same  16-bit conversion, and stores it›for  the  subroutine, so that it knows›where  to  start  putting the incoming›data.››*   Line  1020  executes  the  machine›routine,   and   reads  in  the  data,›checking  for  an  End  Of  File (EOF)›error; #136.  If such an error is met,›the variable BOF is set to zero.››*  Line  1030  retrieves the number of›bytes  long  the  routine  loaded, and›tells  BUF$  that  it  is  X number of›characters long.››*  If  BOF=0, the user may account for›the  EOF  and jump back to the routine›after clearing BUF$.››*  By using this routine, one can copy›files  through  BASIC.   Simply, after›reading in a file, print the string to›disk.››10            CLOSE            #1:OPEN›#1,8,0,"D1:destinat.ion":PRINT›#1;BUF$:CLOSE #1›››The last machine language routine is a›clock.  The Atari has a built in clock›and  doesn't  even use it.  It follows›the  electrical  current  in the U.S.,›which  flows  at 60Mhz.  The following›routine,  written by the Phoenix, sets›up a clock, using page 6 memory (1536)›to store the data, and operates during›each  VBI  (Vertical Blank Interrupt).›You  merely have to supply the current›hour, minutes, seconds, and 60ths of a›second.   You can retrieve the current›time  by  merely  using PEEK commands.›The  only stricture is that if you use›a  graphics  command  (eg. GRAPHICS 0)›you must re-initialize the clock.››32700   FOR  A=1  TO  105:READ  B:POKE›1535+A,B:NEXT A›32705   ?   "Enter  Military  Time  as›Hours,Minutes,Seconds,60ths":    INPUT›H,M,S,SS›32710 X=USR(1611,H,M,S,SS)›32720                             DATA›238,115,6,173,115,6,201,60,240,3,76,95›228,169›32730                             DATA›0,141,115,6,238,114,6,173,114,6,201,60›240,3,76,›95,228,169,0,141›32740                             DATA›114,6,238,113,6,173,113,6,201,60,240,3›76,95,228,›169,0,141,113,6›32750                             DATA›238,112,6,173,112,6,201,24,240,3,76,95›228,169,0,›141,112,6,76,95›32751                             DATA›228,104,104,104,141,112,6,104,104,141,›13,6,104,›104,141,114,6,104,104,141›32752                             DATA›115,6,169,6,170,160,0,76,92,228,0››*  The  PEEK  locations  for  the time›are:››          Hours   - 1648›          Minutes - 1649›          Seconds - 1650›          60ths   - 1651››*  The program first pokes the machine›language   subroutine   into   page  6›memory,  and then prompts you to enter›the time.››*   It   then   GOSUBS   the   machine›subroutine, sending with it the values›of  the  current time, and then starts›the clock.››*  After a GRAPHICS command, just PEEK›in the values of the correct time into›H,  M,  S, and SS, and reintialize the›clock.›››Section Two: BASIC Tricks››Since  Atari BASIC hasn't many special›features,   one   must  compensate  by›"tricking" the system.  These "tricks"›are  actually  ways  around BASIC that›speed  up  processing,  format output,›etc.››The  first  trick deals with filling a›string  with one character.  To fill a›string  with  1,000  spaces, one would›usually do this:››          10 DIM L$(1000)›          20 FOR A=1 TO 1000›          30 L$(A,A)=" "›          40 NEXT A››This  method, though fine programming,›is  SLOW.   The  trick  around it is a›quirk in the BASIC; well, not actually›a  "quirk",  but  a  hidden back door.›The  line  below is the aforementioned›routines equivalent.››10   DIM   L$(1000):L$="  ":L$(1000)="›":L$(2)=L$››Not  only is this routine shorter, but›it's  almost  instantaneous, depending›on  the  size of the string.  I find a›one  second  wait  for  strings in the›xx,xxx  digit  range, but I think that›it's worth the wait.››Side  Note:  If you DIMension a string›at 1000, and aren't filling the ENTIRE›string  with  one  character,  say 500›from a 1,000 character string, and use›the    formula    [L$="    ":L$(500)="›":L$(2)=L$],  it will fill it with 501›spaces.   To  clear  this  up, all you›need  do, is put "L$=L$(1,500))" after›setting  it.   This is true, even when›filling 998 of the 1,000 characters.›››The  next "trick" deals with the INPUT›statement.   Anyone who has programmed›using  the  INPUT statement knows that›it puts a "?" on the screen to signify›an   input   request.    This  can  be›bothersome  to  some,  especially  me,›when  they  want  to make prompts look›nice.    That  "?"  just  looks  outta›place,  and  sometimes  is included in›the returned variable.››There  are  two  solutions.  One is to›write  your  own  "Get-Line"  routine,›using an open keyboard buffer, getting›keypresses,  adjusting  for backspaces›and  control  characters, and using up›memory, OR...››Use  the  following Input command that›is  totally  the  equivalent  of  your›regular INPUT.››          INPUT #16,variable››That's   right!    An   input  through›standard   Atari   BASIC  without  the›dreaded  "?".   It  works exactly like›the standard INPUT command.  Sure, you›could  open  a  channel  to the editor›(E:)   yourself,   but   this   method›requires no additional open buffers.›››Ever  want  to  intialize  a disk from›BASIC?   No,  I don't mean just format›it, I mean put DOS on it too.  Well, I›have good news and bad news.  The GOOD›news  is that you can, the bad news is›that  that's  ALL  you  can put on it;›DOS,  no DUP.  In fact, the writing of›DOS  to the disk is as fast as writing›from DOS itself!››          OPEN›#1,8,0,"D1:DOS.SYS":CLOSE #1››Yes,  that's  it!   All  DOS's  except›SpartaDOS  and  TOPDOS will work, even›the OSA+ DOS's.  You have just written›DOS to your disk from BASIC.›››Did  you  ever  want  to Re-Boot (Warm›Boot)  the computer from BASIC without›hitting System Reset?  Try this:››          X=USR(58487)››This  will  "Warm  Boot" the computer,›but  unlike  the  RESET key, it is the›equivalent  of turning the machine OFF›and  ON again; so you might call it an›artificial  COLD  boot.   You may hold›down  OPTION  as this boot takes place›to  disengage  BASIC.  Its Hexadecimal›number  is  E477. You can do it from a›DOS as well.›››Section Three: PEEK's and POKE's››Did   the   speed   of   Atari   BASIC›processing   ever   bug   you?   Well,›there's   a   way   to  increase  data›processing   33%.   It  will  increase›problem     solving     speed,    data›processing, and graphic plotting.››          POKE 559,0››This  POKE  will shut down ANTIC, thus›shutting   of   the  screen,  so  that›processing  speed  is  increased.   To›turn it back on, use POKE 559,34.›››To  find  out  what  version  of Atari›BASIC  you  have in your computer, you›simply:››          PRINT PEEK(43234)››A  number  32  or  less is revision A.›The  value  64  or less is revision B;›built  into  most  XL's.  And a number›greater  than  64  is  revision C; the›current  version  built  into  the  XE›line.  Though I have an old 800XL, for›some  reason  I  have revision C built›in; a blessing.›››Here  are some keyboard POKE's to play›with:››     *  755,004  - Turns character set›Upside-Down,   and   disables  Inverse›video.››     *   755,008   -   Right-Side   up›character set WITHOUT Inverse video.››     *     755,013    -    Upside-Down›characters WITH Inverse video.››     *   755,010   -   Right-Side   up›character set with Inverse video›                  (Normal mode).›››Special  recognition to XLent software›and  David  Castell  for  creating the›fine  word  processor  used  to create›this text.  BRAVO.››Please  send  me  comments  concerning›these   notes.   A  positive  response›might warrant a Part Two.››                                     ›Hawke››----------------››I  downloaded  this  article  from the›Pandora    BBS   (614)   471-9209   on›10/22/89.   It looks like it came from›the Nine Hells Information Exchange of›Philadelphia (PA) BBS, (215) 785-2625.› I  thought it might be good for those›still  programming  in Atari BASIC.  I›hadn't  seem  most  of the tips before›except  the  one on getting rid of the›question   mark.    I'll   bet  others›haven't  either.  I hope you find this›article helpful. - Grant -›                                      ›