MACE Journal v4n8 Aug 1984

A

Ramblings

Some idle thoughts about our new owners***

WHY SELL ATARI NOW? Another dumb move
by Warner Communications, in this writer's
opinion* Sure, half-billion dollar losses are
no picnic, but that's one hell of a tax write
off* And with Atari's soon return to
profitability, that makes the move even more
strange* They've been watching "MTV" too
long! Do all of us Atarians now own
Ataridores? If you buy that one, I've got some
Michael Jackson concert tickets for you!

ELECTIONS are coming real soon* If you think
you can do a better job than I (or any of the
officers) please let me or past-president
Marshall Dubin know*

TARICON '84 Plans are progressing, slow but
sure* Pre-registration for MACE members will
be held tonight and at the August meeting*
Tickets will cost a minimal $2*00* We
anticipate 20 to 30 booths from ATARI and
OSS down to your local software dealer*

Adult volunteers will be needed* This is an
official MACE activity, and for it to be
successful, we need you to volunteer your
services for the weekend* Set-up will take
place on Friday the 24th, with the show
scheduled the 25th and 26th* Tear-down will
be after 6J00 PM on the 26th* All this takes
place the weekend before Labor Day, so
nobody's vacations will be messed up*
VOLUNTEER YOUR SERVICES TONIGHT!

The official MACE Road Trip took place on
July 4th* Didn't get anyone else to come
along, so it proved to be a nice vacation in
Canada for yours truly and his family*
They've got some real problems with Atari
north of the border* See me after the meeting,
at Tequila Willie's (the un-official watering
hole of MACE), and I'll clue you in on them*
My thanks go out to Steve and Chris Gauthier
for their warm hospitality (and cold Labatts!)*

That's about all this month* Please make
yourself available to help with TARICON if at
all possible! Call the MACE HOTLINE to
volunteer or to get the latest info*

THE MOST IMPORTANT
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Send check or money order to: M.A.C.E., P.O.
Box 2785 Southfield, Michigan 48037.

Won't you take a moment right now and take a
look at the mailing lable? You know* the one
on the back cover* Notice that date in the
upper right-hand corner? It's your
membership expiration date* If it is close*
then renew it now. either by mail or at the
next general meeting* to avoid interruption of
your membership* Also look at the name and
address for any typo's and let me know so
corrections can be made* Your help in this
area will be appreciated!

If you plan on a change in address* try to get
the info to us so our files can be updated at
the earliest passible date*

Thanks alot folks!

Paul R* Wheeler
Membership Coordinator

OSS BASIC XL

Reviewed by Mike Fortuesi

Good old Atari BASIC* Have you ever wished
it could do just a little more? Did you ever
want your programs to run just a little faster?
Did you ever look at programs for other
computers in magazines and wonder just how in
the world you were going to translate them to
the Atari? Did you ever want to write a
program using (sigh of envy) string arrays?
Well, all your wishes have been answered*
Optimized Systems Software's (OSS) BASIC XL
is everything Atari BASIC isn't* and more*

BASIC XL comes to you in the form of a bright
orange cartridge enclosed in a cheerful yellow
binder* The binder contains a reference
manual and the tutorial "Thirty Days to
Understanding BASIC XL*" a guide for the
beginning user* In all* I found the
documentation clear and well-explained* The
reference section of the manual reads very
much like an expanded version of the Atari
BASIC Reference Manual* This should come as
no surprise* since BASIC XL was written by
the same company responsible for Atari
BASIC* In a few instances* I found some
minor errors in the manual* both in the
reference section and the tutorial* I sincerely
hope OSS intends to correct these errors as
soon as possible*

First of all* I would like to clear up any
misconceptions the title may imply* BASIC XL
will run on any Atari computer* not just the
new XL models* It is upwardly compatible
with Atari BASIC} this means it will run
normal BASIC programs* but programs written
using special BASIC XL features will not work
with Atari BASIC* And what features it has!
BASIC XL has the following commands not
present in Atari BASIC*

* BGET, BPUT - Allows you to do direct
binary I/O* This was possible in BASIC only
through a series of POKES and a machine
language call* Now operations such as saving
hi-res screens to disk are almost trivial*

# DEL - Delete a range of line numbers
from your program*

* DIR* ERASE* RENAME, PROTECT,
UNPROTECT - Say good-bye to the DOS menu*
These important disk functions are only a
command away*

# DPOKE - Performs a word-oriented (16
bit) POKE into two successive memory
locations* Ever see program segments that
ran like this?

100 HI=INT(MEM/256)*LO=MEM-256*HI

no poke addr,lo:poke ADDR+1,HI

In BASIC XL, that would look like this!
100 DPOKE ADDR,MEM

DPEEK is the counterpart to DPOKE, and
works in much the same manner*

# FAST - Speeds up program execution by
doing a precompile of the program in memory*
More on this later*

# IF***ELSE***ENDIF - There is is more
here than just IF***THEN***ELSE* More on this
later*

# INPUT with a prompt following, as in
this example*

100 INPUT "NAME YOUR POISON",A$

# String concatenation - In Microsoft
BASIC, strings may be added together like
this!

100 A$="HI"
110 B$="THERE"
120 C$=A$+" "+B$
130 PRINT C$

When RUN, the program would produce}
HI THERE

In BASIC XL, line 120 would read:
120 C*=A$," ",B$

# LOMEM - Change the system low memory
pointer to save space for assembly language
routines, custom character sets, etc*

# LVAR - Lists all variable names and the
line numbers they can be found to any output

device (screen, printer or disk file*)

* MOVE - Perform block moves of memory
at machine language speed* Blocks may be
moved either up or down in memory* No
address checks are made* so watch out!

* PMGRAPHICS, PMCLR* FMCOLOR,
PMMOVE* FMWIDTH* MOVE* MISSILE* BUMP
- A complete set of player-missile commands
and functions* A system memory map is now
no longer a necessity to use player-missile
graphics from BASIC*

* NUM - Auto line numbering* A
convenience to save time when entering
programs*

* PRINT USING - Allows you to produce
neat* formatted output without using
subroutines to justify numbers and add
trailing zeroes before. printing*

* RENUM - When you're finished with your
program* why not renumber it so people can't
tell you spent the past week or so hacking
away at it?

* RGET* RPUT - Perform I/O using records
of mixed strings and numeric variables* Most
useful in file processing*

* SET - A command that gives you control
over various BASIC XL system settings* Do
you hate the question mark an INPUT
statement produces as much as I do? Change
it to a greater-than sign (">") as follows?

SET 2,ASC("> M )

SET allows you to change other system
settings as well. The BREAK key can be
enabled* disabled* or return an error* The
spacing for tab stops can be changed*
Missiles can either wraparound from the top
of the screen to the bottom* or roll off the
edge* Missiles can also be grouped into a
fifth player* FOR***NEXT loops can be set to
execute at least once* or zero times* You can
even decide whether the USR function should
push a parameter count on the 6502 stack*

* TAB - Another feature missing from
Atari BASIC that was usually done using
various POKES to cryptic memory locations*

* TRACE* TRACEOFF - Prints the line
number currently being executed on the
screen* This can be a timesaver when
debugging*

* WHILE***ENDWHILE - A control
structure that allows you to perform a group
of statements until a certain condition exists*
More on this will follow as well.

Is that enough for you? No? Well* then let's
take a look at the BASIC XL function library:

* ERR - ERR(O) will return the latest error
number* ERR(l) will return the line at which
the error occured* This can be useful for
error-handling routines.

* HEX* - Converts an integer number up to
65535 to a hexadecimal string. BASIC XL can
also operate and do calculations with
hexadecimal constants* as in the following
example!

100 PRINT HEX*(USR(*680**3FFA**2972»

Typing PRINT *FCB5 would yield a result of
64693* BASIC XL eliminates the need for
hexadecimal-decimal conversion tables and
programs*

* FIND - Finds the location of a substring
in a larger string* no matter how large the
string is*

* HSTICK* VSTICK - Returns -1, 0* or +1
for the joystick both horizontally and
vertically* Useful in games and etch-a-s ketch
type programs*

* LEFT*. RIGHT** and MID* - Microsoft
BASIC* eat your heart out. These functions
return substrings of a larger string. Of
course* you can still do things they way they
are done in Atari BASIC (e*g* A*(M*N))*

* FEN - PEN(O) returns horizontal
coordinates of the light pen* PEN(l) returns
vertical coordinates*

* PMADR - Finds the address in memory
where a given player-missile image is stored*

* RANDOM - Returns a random integer
between any two numbers* For a random
number between 1 and 100* try:

100R=RANDOM(1,100)

* SYS - Returns information on various
BASIC XL system settings (the same ones you
can change with the SET command)*

And let us not forget some of the incidental
benefits of BASIC XLJ

* String Arrays - This is best explained
with an example* The command*

DIM A$(20,40)

DIMensions an array of 20 elements* each 40
characters long* Referencing an element of
the array would look like this*

PRINT A$(I}>

This references element I in the array* A
substring of that element would look like*

PRINT A$(I}M*N)

* Auto-dimension of strings - BASIC XL
will automatically DIMension a string that has
not been previously DIMensioned to a length
of 40 characters* The auto DIMension length
can be changed with the SET command*

* Full English error messages - Never run
to the reference manual to find out what
"ERROR- 13 IN LINE 32015" means again*

* Formatted listings - BASIC XL will print
listings in upper and lower case* indenting
FOR***NEXT and WHILE***ENDWHILE loops*
and IF***ELSE***ENDIF structures as well*

* Program entry in upper/lower case and
inverse video - BASIC XL will automatically
convert all characters except those in quotes
to upper case normal video* so you can enter
programs in lower case*

* Boolean arithmetic - Operators have now
been provided for bitwise AND* OR and EOR
of two numbers* Machine language
programmers know what I'm talking about;
others can be content to know they exist*

* FAST program execution - Whenever
Atari BASIC encounters a GOTO* GOSUB* or

NEXT statement* it has to search for the line
to transfer control to* starting at the very
beginning of the program and continuing until
the line is found* Obviously* the longer your
program is* the slower subroutines and such
near the end will run* When BASIC XL sees
the FAST command* it looks at the program in
memory* It replaces the line numbers after
GOTOs and GOSUBs with the actual memory
addresses of those lines* As a result*
programs run much faster* The speed
improvement depends on the program* OSS
claims programs can run up to four times
faster? my experience is about twice normal
speed or less* Note that programs that
perform a large number of calculations will
not benefit very much from the FAST command*
Others may benefit very* very much* I have
one game in BASIC that is actually too fast to
play*

* IF***ELSE***ENDIF capability - Other
BASICS have IF**THEN***ELSE* BASIC XL has
more* Try this example (from the BASIC XL
manual) on for size*

200 IF AM001FRINT "TOO BIG"
210 A=100

220 ELSE JPRINT "A-OK"
230 ENDIF

Look at line 200 carefully* Note that there is
no THEN statement — only a colon* When using
IF***ELSE***ENDIF in BASIC XL* ALL
statements (even those on multiple lines)
between the following colon and the ELSE
statement are executed if the statement is
true* and ALL statements between the ELSE
and ENDIF are executed if the statement is
false* If you didn't quite catch the
implications of all this* here's another
example from the manual*

100 IF A>B J REM SO FAR A IS BIGGER
110 IF A>C i PRINT "A BIGGEST"
120 ELSE J PRINT "C BIGGEST"
130 ENDIF
140 ELSE

150 IF B>C I PRINT "B BIGGEST"
160 ELSE { PRINT "C BIGGEST"
170 ENDIF
180 ENDIF

If you like the way that example reads* you
will definitely have a fun time with BASIC XL*

5

* WHILE***ENDWHILE - Another powerful
control structure, WHILE***ENDWHILE allows
you to set up a loop that executes only as long
as some condition holds true* Again* an
example*

100 WHILE FEEK<5327?)06JENDWHILE

This line will patiently wait until the START
key is pressed* As long as the condition holds
true* the loop will execute* When the START
key is pressed* the condition becomes false*
and BASIC XL stops executing the loop*
Contrast this with the equivalent BASIC code*

100 IF PEEK(53279K>6 THEN 100

Using the I F * * ♦ E L S E * * * E N D I F and
WHILE***ENDWHILE capabilities of BASIC XL,
it is possible to write structured BASIC
programs* GOTO statements are no longer
needed*

At this point, you may be wondering "How
much extra memory are all these nifty
features going to take up in my Atari?" The
answer* not a single byte more than Atari
BASIC* That's right, the BASIC XL cartridge
takes up only 8K in an Atari on power-up*
With OS/A+ version 2*1 on my Atari 800,
BASIC XL reports 31502 free bytes of memory
when PRINT FRE(0) is typed* With Atari DOS
2*0, 32274 bytes of memory are free. These
figures are the same for Atari BASIC — check
them out yourself* The designers at OSS
invented a special bank-switching system that
keeps only an 8K portion of the cartridge in
memory at one time, while the other 8K is
hidden from the machine* The result? With
BASIC XL, you can have your cake and eat it
too* But that's not all! When used with DOS
XL, another OSS product, another 5K is opened
for your use* DOS XL was specifically
designed for use with BASIC XL, and locates
itself in the RAM that is occupied by the
cartridge* When DOS is needed, the BASIC XL
cartridge ROM is turned completely off,
exposing the RAM underneath* When used
with DOS XL, about 37K is free for
programming in BASIC XL*

Now, for some of my complaints about BASIC
XL* My first complaint is the cartridge itself,
which has tin connector tabs rather than gold

ones* I have worked with early Ataris that
had tin-plated connector tabs on their memory
boards, and I know what a pain they can be*
The boards usually had to be cleaned weekly
to avoid system crashes that destroyed hours
of work* Obviously, a product of this quality
deserves a better cartridge* My second
complaint concerns some possible bugs in the
program* I bought BASIC XL after seeing it
run on a friend's machine a few weeks earlier*
When I plugged my BASIC XL cartridge into my
Atari, I discovered I had version 1*02* My
friend's version 1*0 BASIC XL was purchased
only a month earlier* I noted that his
cartridge had some compatibiltiy problems
with some Atari BASIC programs in my
collection* One program stopped running with
a LINE NOT FOUND error* This error occurs
if you try to GOTO a line that doesn't exist in
your program* The problem was that the line
where the error occured was a DRA WTO
statement! A few programs (such as the
Scriptor Word Processor from COMPUTE!
Magazine, April 1983 and some games from
COMPUTE!) wouldn't run at all. The revision
1*02 cartridge I received did not have these
problems (except Scriptor — it still doesn't
work), but one cannot be sure if other
problems exist* It seems safe to say that
most Atari BASIC programs will run properly
under BASIC XL, and the ones that don't have
exotic machine language routines and other
"tricks" in them that make problems for BASIC
XL* If I find a program that doesn't work in
BASIC XL, I simply run it under Atari BASIC*
The original bugs of Atari BASIC have been
fixed, however, and you need not worry about
a system lock-up while editing a program*

The only real competition for BASIC XL is
Atari Microsoft BASIC II* This combination
cartridge/diskette package does have a few
features that BASIC XL doesn't offer (such as
integer variables and user-defined functions
of the type DEF FN), and it does offer faster
math computation than BASIC XL (BASIC XL
uses the slow Atari floating point ROMs)* But
when you consider that BASIC XL is
compatible with Atari BASIC, has
syntax-checking, takes up 8K in your Atari as
opposed to 18K, offers a FAST command, and
comes all on one cartridge instead of a
cartridge and a disk, BASIC XL wins hands
down* In short, BASIC XL is the first BASIC
worthy of the computer it was written
for — the Atari*

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— MEMORY MOVER —
AND SCREEN SAVE

MEMORY MOVER was written to demonstrate
the use of BASIC strings to move massive
amounts of memory at machine language speed*
Advanced BASIC programmers will find these
routines helpful to move player-missile graphics
or other data to new locations quickly* Less
advanced programmers may use this program to
design* save and recall game-board screens and
everyone will find this a fun way to doodle on
the screen and get some useful insight on how
strings are managed in Atari Basic*

This program works on either disk or
cassette based systems with 24k or more
memories* It can be condensed to fit into 16k
machines by removing all of the REM statements*
replacing the constants with variables* and using
multiple statement lines. A nice feature is the
use of a string that has been DIMed to 1 to
handle over 4k of memory* This is done by
modifying the variable value table after BASIC
has performed its space allotment* I used
modified strings to move data around in memory
and not pay a penalty in DIMed string overhead*
Now on to the program*

It is important in this program that SCREEN*
is the first variable on the variable tables*
After you have typed in the program* LIST it to
disk or cassette and then re-ENTER it* This will
clean up the variable tables and put SCREEN* in
the first position and easy to find in the
variable value table*

Lines 50 to 220 are the drawing routine*
Lines 50 to 110 set up the screen and provide
instructions for the prograrrr user* In lines 120
through 160, 1 use subscripted variables to help
change the X and Y locations of the cursor* That
eliminates a lot of IF-THEN statements and
leaves only those needed to check for the edge
of the screen* If you modify this program for
other graphics modes, don't forget to change the
maximum X and Y values* Lines 170 through 210
are used to detect the end of the drawing
routine* change color* and provide erasing of
lines already drawn* You might wish to add lines
to change the color* luminosity* etc* Don't forget
to add routines to re-insert those changes after
you bring the screen back from storage* Line 220
puts the dots on the screen and loops back*

The flashing routine in lines 250-360 is a
graphic way to demonstrate the memory mover
technique* Line 250 through 310 provide
instructions and reset the graphics mode* After
a GRAPHICS command* it is necessary to
reposition SCREEN* to overlay the new screen
position* This must be done before you use this
string after a GRAPHICS command even if you
stayed in the same mode* Lines 320 and 330 look
for a signal to end the routine or to change
strings*

Lines 340 and 350 do the real work by making
SCREEN* equal to one of the holding tank
strings* Instead of moving the screen data
pointer* I moved all of the screen data* including
the display list* As a program routine, this is
not efficient but it is a graphic way of
demonstrating the memory mover* When you run
the program* you will see that you can swap 4200
bytes of memory fast enough to superimpose two
images on the screen at apparently the same
time* If you can do it that fast for screen data*
you can do it that fast for other data* Line 360
loops you back for more exchanges*

Lines 370 though 510 initalize the program,
SIZE sets both holding strings to the correct
DIMension for GRAPHICS 7. Room has been
allowed for both the display list and screen
data* If you modify this program for other
graphics modes* don't forget to change the pokes
on line 1060-1070* 1 100-1110 and 1360 to
conform to the new graphics mode memory
requirements* Line 430 loads a machine language
input/output routine into a string call CIO**
Lines 450 and 460 load the subscripted variables
used to read the joystick* Lines 490 to 510
remove all data from the holding tank strings
SHOLD1* and SHOLD2* and open them up to
their DIMed length. If these strings are not
opened up, SCREEN* might send or receive only
one byte of data* The string cleaning was thrown
in just to show you a fast way of doing it*

Lines 520-610 were added so you could
bringing back a screen that you had previously
stored without going through the drawing
routine*

Lines 620-740 send the program through two
draw and save cycles* The variable T stands for
test* This was added to show you that the text
data is also being moved. Screen data addresses
change each time a GRAPHICS command is used.
SCREEN* must be repositioned to conform to the
changed data address* This is done by the
GOSUB 940* The variables OP1 and OP2 stand

S

for Operation, OP1 is used to open an I/O
control block for input or output operations* OP2
does the same for a CIO location called on by the
machine language routine* These variables and
WORD$ saved writing different routines for
input and output*

Line 750 sends the program to the flashing
routine and lines 760-870 call for screen data to
be brought in from outside storage and flashed
on the screen in the flashing routine* 880 ends
the program when you are finished experimenting
and 890-920 contain the DATA needed for the
CIO* string machine language routine and the
joystick readers*

The heart of this program is in lines
930-1140* BASIC addresses strings and
subscripted variables by their offset from the
start of the array table instead of their
absolute address in memory* To modify a string's
address, you must first find out where the array
table is. Next, since the strings offset address*
current size and DIMensioned size is kept in the
variable value table* you must find the value
table and the string's position in it* By naming
SCREENS first in the program* SCREENS has the
first position on all of the variable tables* The
second named variable has the second position
and so fourth*

In the variable value table, byte zero and one
tell what kind of variable it is and what number
variable it is* In string and array variables, byte
two and three tell its offset from the start of
the array table* In string variables, Byte four
and five tell how long it is at a given moment in
the program and byte six and seven tell how long
it has been DIMensioned to*

I documented this section with wordy
variable names and lots of REM statements for
easy future refferance* Each string variable
repeats this pattern* If you need more than one
string mover for future programs, DIM it second
(etc.) in the program* That way it will be easy to
find on the value table.

Lines 1150 to 1390 are the input/output
section. A TRAP statement on line 1 170 protects
the program from crashing through careless
naming of disk files. Lines 1180-1260 get the
proper I/O device and a file name if necessary.
Line 1270 first closes a file that may have been
left open due to error then. Then it OPENs I/O
control block one with the code controlled by
OP1 and the appropriate name carried by
DISKN*. Lines 1280 sets the correct GRAPHICS
mode and insures that string SCREENS overlays

the screen data area. If their is an output
operation, line 1290 puts the information to be
transmitted on the screen* Line 1310 tells CIO
(Central Input/Output, a part of the operating
system) what kind of I/O operation will be
handled* Lines 1340 tell CIO where to start
taking its data* Line 1360 tell how many bytes of
data to take and line 1370 call the CIO to action
via a short machine language routine. The 16
tells CIO that control block one is being used*
Line 1380 CLOSEs the control block and removes
the trap so that any other errors in the program
can be detected and referanced. If there is an
error in I/O operations, the error is TRAPed to
lines 1400-1410 which allow you to recover by
finding out what is wrong and correcting it
without loosing the screen you have drawn*

Remember 1

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10 REM MEMORY MOVER AND SCREEN SAVER
20 REM

30 DIM SCREEN*(l)JGOTO 370

40 REM SCREEN DRAWING ROUTINE

50 GRAPHICS 7!C 1=1

60 ? "TEST ";TJ" JOYSTICK DRAWS LINE"
70 ? "FIRE BUTTON ERASES DRAWING"
80 ? "SELECT CHANGES COLOR"
90 ? "START BUTTON SAVES DRAWING"}

ioo x=5o:y=5o:plot x,y

110 COLOR C!S=STICK<0)

120 X=X+JOYX(S)!Y=Y+JOYY(S)

130 IF X<0 THEN X=0

140 IF XM59 THEN X=159

150 IF Y<0 THEN Y=0

160 IF Y>79 THEN Y=79

170 POKE BUTTON,8JIF PEEK(BUTTON)=6

THEN RETURN

180 IF PEEK(BUTTON)=5 THEN Cl=Cl+15FOR

1=1 TO 40 'NEXT I

190 IF Cl>3 THEN Cl=l

200 IF STRIG(0)=1 THEN C=C1

210 IF STRIG(0)=0 THEN C=0

220 PLOT X,YJGOTO 110

230 REM FLASHING ROUTINE

240 GRAPHICS 0

250 ? "READY FOR FLASHING ROUTINE"
260 ? "THIS ROUTINE MOVES 4,192 BYTES OF"
270 ? "MEMORY AS FAST AS YOU CAN PRESS
THE"

280 ? "FIRE BUTTON, WHEN YOU ARE DONE"
290 ? "EXPERIMENTING, PRESS THE START
BUTTON"

300 ? {? "PRESS RETURN TO START

ROUTINE" 'INPUT ANSWERS

310 GRAPHICS 7JGOSUB 930

320 POKE BUTTON,8JIF PEEK(BUTTON)=6

THEN RETURN

330 S=STRIG(0)

340 IF S=0 THEN SCREEN*=SHOLD2*

350 IF S=l THEN SCREEN$=SHOLDl*

360 GOTO 320

370 REM INITIALIZATION

380 SIZE=4 1 92 J V256=256 :BUTTON=53279

390 DIM SHOLDl$(SIZE),SHOLD2*(SIZE)

400 DIM

JOYX(15>,JOYYU5),DISKN*<15),FILENAME$U2)
410 DIM C*(1),ANSWER$(1),CIO$(7),WORD$(10);
C$=C HR$(0)

420 REM BUILD CIO STRING
430 FOR 1=1 TO 75READ
S:CIO$(I,I)=CHR$(S)JNEXT I
440 REM LOAD JOYSTICK DATA
450 FOR 1=1 TO 15,'READ S{JOYX(I)=S

460 READ S.'JOYY(I)=S.*NEXT I

470 GOSUB 930,'REM MODIFY STRING SCREEN

480 REM OPEN UP CLEANED STRINGS

490 SHOLDl$=C$!SHOLDl$<SIZE)=C$

500 SHOLDl$(2,SIZE)=SHOLDl$

5 1 0 SHOLD2*=SHOLD 1 $

520 REM CHOOSE FUNCTION

530 GRAPHICS 0

540 ? J? "DO YOU WANT TO DRAW PICTURES
OR BRING"

550 ? "BACK THOSE YOU HAVE DRAWN?"

560 ? t? "TYPE D FOR DRAW"

570 ? " B FOR BRING BACK".'?

580 ? "THEN TYPE RETURN"}?

590 DJPUT ANSWER*

600 IF ANSWER*="B" THEN 810

610 IF ANSWER*0"D" THEN 530

620 REM DRAW 2 PICTURES AND SAVE EACH

630 REM DRAWING 1

640T=i:GOSUB50

650 GOSUB 940

660 SHOLD2*=SCREEN$:SHOLDl$=SHOLD2*

670OFl=8:OF2=ll

680 WOPJD*="SAVE TO"

690 GOSUB 1160

700 REM DRAWING 2

710 T=2JGOSUB 50

720 GOSUB 940

730 SHOLDl*=SCREEN*

740 GOSUB 1160

750 GOSUB 230:REM FLASHING TEST

760 GRAPHICS 0.'?

770 ? "ALL SCREEN DATA WILL BE

OVERWRITTEN"

780 ? "BY DATA THAT WILL BE BROUGHT
BACK"

790 ? "FROM THE STORAGE MEDIA"

800 FOR 1=1 TO 5005NEXT I

810 WORD*="BRING FROM"

820 OPl=4:OP2=7

830 GOSUB 1160

840 SHOLD2*=SCREEN*

850 GOSUB 1 160

860 SHOLDl*=SCREEN*
870 GOSUB 230

880 GRAPHICS 0.'? "THIS COMPLETES THE
TEST":END

890 DATA 104,104,104,170,76,86,228

900 DATA 0,0,0,0,0,0,0,0,1,1

910 DATA 1,-1,1,0,0,0,-1,1,-1,-1

920 DATA -1,0,0,0,0,1,0,-1,0,0

930 REM MODIFY ADDRESS OF SCREEN*

940 DISPLAYLIST=PEEK(560)+

V256*PEEK(561)

950 VARIABLETABLE=PEEK(134)+V256*
PEEK(135)

lO

960 ARRA YT ABLE=PEEK( 1 40)+ V256*PEEK( 1 4 1 )

970 OFFSET=DISPLAYLIST-ARRAYTABLE

980 HI=INT<OFFSET/V256)

990 LO=OFFSET-V256*HI

1000 REM LOW & HI BYTE OF NEW ADDRESS

1010 REM OF STRING SCREEN$

1020 POKE V ARI ABLET ABLE+2»LO

1030 POKE VARIABLETABLE+3,HI

1040 REM LOW & HI BYTE OF NEW CURRENT

1050 REM SIZE OF STRING SCREEN*

1060 POKE VARIABLETABLE+4,100

1070 POKE VARI ABLET ABLE+5» 1 6

1080 REM LOW & HI BYTE OF NEW DIMED

1090 REM SIZE OF STRING SCREEN*

1100 POKE V ARI ABLET ABLE+6 > 1 00

1110 POKE V ARI ABLET ABLE+7 ,32

1 120 SCREENHI=INT(ADR(SCREEN*)/V256)

1130

SCREENLO=ADR(SCREEN*)-SCREENHI*V256
1140 RETURN

1 150 REM NAMING THE OUTPUT FILE
1160 GRAPHICS 0
1170 TRAP 1400

1180 ? J? "DO YOU WISH TO "JWORD*
1190 ? "DISK OR CASSETTE CD/C]?":?
1200 ? "TYPE D FOR DISK OR C FOR
CASSETTE"?

COMING
ATTRACTIONS
August 21st«
Meeting

Here's the tentative schedule of topics for the
August meeting. Please note that this
meeting IS on the 3rd. Tuesday of the month,
as will all further meetings this year be.

- Business meeting

- Atari Tennis demo

- Letter Perfect demo

- CBS Educational Software demos

- TARICON '84 workers meeting

Tom Sturza
Program Coordinator

1210 INPUT ANSWER*

1220 IF ANSWER*="C" THEN

DISKN*="C:"!GOTO 1270

1230 IF ANSWER*<>"D" THEN GOTO 1160

1240 ? '? "TYPE IN THE FILENAME AND

PRESS RETURN"

1250 INPUT FILENAME*

1260 DISKN*="D{"1DISKN*(3)=FILENAME*

1270 CLOSE #l!OPEN #1,OP1,0,DISKN*

1280 GRAPHICS 7}GOSUB 940

1290 IF OPl=8 THEN SCREEN*=SHOLDl*

1300 REM SET UP IOCB

1310 POKE 850,OP2

1320 REM LOW BYTE AND HI BYTE OF

1330 REM WHERE TO START MOVING DATA

1340 POKE 852,SCREENLOJFOKE 853,SCREENHI

1350 REM LOW & HI BYTE OF HOW MANY

BYTES TO MOVE

1360 POKE 856,100JPOKE 857,16

1370 X=USR(ADR(CIO*),16)

1380 CLOSE #i:TRAP 50000

1390 FOR 1=1 TO 200JNEXT I {RETURN

1400 ? J? "YOU HAVE MADE AN ERROR"

1410 ? 5? "PLEASE TRY AGAIN JGOTO 1160"

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routines
Filenames

by Phil Heavin

The device independence that is an integral part of
the ATARI operating system is a very powerful and
useful feature that BASIC programmers do not
usually utilize to its fullest extent.

A user of a program that writes an ASCII type
output file should have the flexability when he runs
the program to direct its output to any device on his
computer. This can be achieved very easily on the
ATARI by simply prompting the user for a complete
file string and using that string in the open
statement.

The above approach has two drawbacks. The first is
that all users must understand the file naming
conventions to give even the simplest response.
Second, it would be nice if the majority of the time
the user could get what he wants by typing just a
RETURN.

The following example program demonstrates the
use of the subroutine GETFILE. Given the default
file string, DEF*, it will prompt the user for his
input, apply the default for each separate portion of
the file specification and return the string FILE*
which can be used in the OPEN statement.

100 REM

20035 FFE*=DEF*
20040 GOSUB fSS

20050 DFDEV$=DEVi 5 DFNAHEi=NANE$ J
DFEXTi=£XTi

20060 PRINT "("JDEF*;">"t
20070 INPUT FILE*
20080 GOSUB fSS

20090 If DEV$="" THEN DEV*=0fDEV$
20100 F NAME*-"' THEN NAMEt=0FNAME*
20110 F EXT$="" THEN EXT$=DfEXT$
20120 FU£*=0EV*
20130 FFE$(LEN<FILEi)+l)=*AME*
20110 FFE*(L£N<FILE$>+1)=EXT$
20150 RETURN

20500 REN

20510 REN | fSS - PILE STRING SCAN

20511 REN |

20512 REN | INPUT:

20513 REN | FILE* - PILE STRING

20514 REN |

20515 REN | OUTPUT:

20516 REN | DEW - DEVICE

20517 REN | NAME! - PILE NAME

20518 REM | EXT$ - PILE EXTENTION
20520 REN

12

110 REN | PROGRAM TO DEMONSTRATE |
120 REM | PROMPTING FOR A PILE NAME |
130 REM | HITH DEFAULTS I

140 REM —

200 DIM DEPf(16),FILE$(16),DEV$(3),
DFDEv$<3) ,NAMEI<8) ,DFNAME$<8> ,EXT*<4) ,
DFEXTi(4),REST*(12)
210 LET GEFFE=20000
220 FSS=20500

250 REM

260 REN | BODY OF PROGRAM GOES HERE I

270 REM

300 DEF*="D}OUFILE.DAT"

310 GOSUB GETFILE

320 PRINT "OPEN PILE "JFILEi

330 PRINT

340 GOTO 310

20000 REM —

20002 REM
20004 REM
20010 REM

20020 REM

20021 REM

20022 REM

20023 REM

20024 REM

20025 REM

20026 REM

20027 REM

20028 REM

20029 REM

20030 REM

20031 REM

getfile routine
prompt user for filename
hith default and apply
them to the response

input:

def$ - default file

STRING

output:

PILE* - RESULT FILE
DEV* - RESULT DEVICE

NAME* - RESULT NAME
EXT$ - RESULT EXTENTION

20530 DEV*=""
20540 NAME$=""
20550 EXT$=""
20555 REST$=FILE$
20560 IC=i:LC=LEN(FILE$)
20570 F IC<=LC THEN IF FTLENICIC)
O":" THEN IC=IC+i:G0T0 20570
20580 F IC«C THEN DEV*=FILEi<l,IC>:
REST$=""}F IC<LC THEN REST$=FILE$(IC+1)
20585 FILE$=REST$
20590 IC=i:LC=LEN(FILE$)
20600 F IC<=LC THEN F FILE$(IC,IC)
<>"." THEN IC=IC+i:G0T0 20600
20610 IF ID1 THEN NAME*=FTLES(1,IC-1>
20620 F IC<=LC THEN EXT$=FILE$(IC)
20630 RETURN

Run this program and try several responses to the
prompt. As you will see, typing RETURN would cause
the output to be written to "DJOUTFILE.DAT".

If, however, this were just a test run and you respond
E: the resultant file string is E50UTFILE.DAT which
means the output would be displayed on the screen.

For printed output you would respond with P:. If you
wanted the output to a different file name on disk you
would just type the name, for example, MYFILE. The
output file will be DJMYFILE.DAT.

If the filename is ok but you are lucky enough to have
another disk you can direct the output there by typing
D25 causing the file string to be D2JOUTFILE .DAT.

The examples could be continued but rather, try
different responses to the sample program. Then use
the subroutines in your programs. It will make them
more usable for you and those who use your program.

SINCE YOU

By Kathy £ Tom Sturza

Q{ Why can't M*A*C*E* print a list of the
Special Interest Groups (SIG) in each issue of
the J ournal?

A i We would gladly do so if the
Chairpersons of the SIG's would keep us
informed of who is in charge and where to
contact therm Your current officers haven't
had too much success in this area*

However* the following list is the last active
list that I have* You may have to track down
the new chairpersons*

ASSEMBLER SIG

Todd Meitzner, (313)542-1752

EDUCATION SIG

Mark Davids* (313)774-9709

FORTH SIG

Tom Chrapkiewicz, (313) 772-8291

Not a very long list* is it? There have been
other SIG groups in the past* J ust to name a
few* Telecommunications* BASIC* and
Beginners* We've also had suggestions for a
PILOT SIG* a LOGO SIG* and a Newsletter SIG*

SIG memberships are FREE but require
M*A*C*E* members to organize on their own*
M*A*C*E* officers do NOT arrange for SIG's to
be created or for meeting locations* Such
meetings are usually held in members homes
or in local computer stores*

Your officers agree that M*A*C*E* would be a
much more worthwhile organization if we had a
large number of active SIG's* What do you
think?

A COURSE DESCRIPTION FROM THE STUDENT
HANDBOOK OF FUNKY WINKERBEAN

COMPUTER MATH 101 — (PREREQUISITE -
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In Computer Math* you'll learn programming*
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and how to change the batteries in your pocket
calculator*

The language of the computer is called BASIC
and you can use it to write programs* solve
problems* and communicate with your friends
in hyperspace*

Once you've mastered the computer* you
should be able to eliminate counting on your
fingers once and for all!

C I I

SOFTWARE TRENDS

I 7 □

Attention MACE Members** You receive an
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CHAOS, MACE and the City of Southfield present

Taricon '84

AN ATARI ONLY COMPUTER CONVENTION

August 25-26, 1984

SOUTHFIELD CIVIC CENTER PAVILLION

SOUTHFIELD, MICHIGAN

Devoted Exclusively To Atari Home Computers

and Related Support Products

CONVENTION FEATURES

* Displays by Software, Peripheral and Accessories

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For more information, send for our full pre-registration flyer:

TariCon '84
P O Box 2785
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or call 313 978 2458

14

MICHIGAN ATA RI COMPUTER ENTHUSIASTS

P=».0. Box 2785J Southfield, Mi* 48037

BULLETIN BOARDSJ MAIN 978-1635/ WEST 582-0657
MACE/TARICON HOTLINE! INFO (voice) 978-2458

PRESIDENT

Michael Lechkun

32229 Ruehle
Warren, MI 48093
978-2458(CompuServe:70655,645)

VICE-PRESIDENT
Wallace Duvall
15579 Chestnut
Roseville, Mi. 48066
772-1982

PROGRAM COORDINATOR
Thomas Sturza
18684 Purlingbrook
Livonia, Mi, 48152
477-2345

DISK LIBRARIAN
Chet Gonterman
35088 Savannah Lane
Farmington Hills, Mi. 48018
553-7443

TREASURER

CASSETTE LIBRARIAN
James Phillips
40008 Cambridge, Bldg 23-Apt 103
Canton Township, Mi. 48187
981-1523

CORRESPONDING SECRETARY
Jane Simon
2345 Pinecrest

Ferndale, Mi. 48220
399-1694 (CompuServe: 74065,1545)

RECORDING SECRETARY

Barbara J . Franczyk
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231-2531

MEMBERSHIP CHAIRMAN
Paul Wheeler
14842 Fielding
Detroit, Mi. 48223
538-364?

M»AtC«E* JOURNAL EDITOR
Marshall S* Dubin
3237 Doral Drive
Rochester, Michigan 48063
(313) 375-9047

x:t meeting: 8/21/84} 7:00 IRIM

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PAGE 6 magazine is a top quality magazine
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Up to 48 glossy pages in each issue of articles,
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USER GROUP SECRETARIES

PAGE 6 is run on the same lines as many User Groups.
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