*><*<>*› This   article   reprinted   from  the› M.A.G.I.C. Newsetter Nov. 1990, by OL'› HACKERS,  with  thanks. It adds to the› prior reported PEEKS and POKES,  along› with  machine   language   programming› tips.››     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.    (Editor.    I    strongly› disagree.   I   find   BASIC   a   fun› programing   tool,   in spite  of  its› limitations. A.P.)››       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$(1,X):RETURN››  *  MEM  is  the  amount of characters› that BUF$ 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,› 113,6,104,104,141,114,6,104,104,141›› 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   off  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. (Editor: I concur.› Have been using it for years  to  make› up  the  newsletter!  Am now trying to› learn  about  another  FANTASTIC  Word› Processor! A.P.)›› 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, 8 BIT librarian for M.A.G.I.C.›                 <<>><<>>››