Applesoft: Internals--Miscellaneous Routines



PTRGET          DFE3

Read a variable name from CHRGET and find it in memory.  On entry TXTPTR

points to the first character of the variable name. On exit the address to the

value of the variable is in VARPNT and Y,A.  If PTRGET can't find a simple

variable it creates one. If it can't find an array it creates one dimensioned

from 0 to 10 and sets all elements equal to zero.



GETARYPT        F7D9

Read a variable name from CHRGET and find it in memory.  On entry TXTPTR

points to the first character of the variable name. This routine leaves LOWTR

pointing to the name of the variable array.  If the array can't be found the

result is an OUT OF DATA ERROR.



FNDLIN          D61A

Searches the program for the line whose number is in LINNUM.

On exit:

 C set LOWTR points to the link field of the desired line.

 C clear then not found.  LOWTR points to the next higher line.



DATA            D995

Move TXTPTR to the end of the statement.  Looks for the ":"  or eol (0).



DATAN           D9A3

Calculate the offset in Y from TXTPTR to the next ":"  or eol (0).



REMN            D9A6

Calculate the offset in Y from TXTPTR to the next eol (0).



ADDON           D998

Add Y to TXTPTR.



SCRTCH          D64B

The "NEW" command.  Clears the program, variables, and stack.



CLEARC          D66C

The "CLEAR" command. Clears the variables and stack.



STKINI          D683

Clears the stack.



RESTOR          D849

Sets the DATA pointer, DATPTR, to the beginning of the program.



STXTPT          D697

Set TXTPTR to the beginning of the program.



BLTU            D393

Block transfer makes room by moving everything forward.

On entry:

Y,A and HIGHDS = destination of high address + 1

         LOWTR = lowest address to be moved

        HIGHTR = highest address to be moved + 1

On exit:

LOWTR is unchanged

HIGHTR = LOWTR - $100

HIGHDS = lowest address transfered - $100



REASON          D3E3

Makes sure there's enough room in memory for another variable. Checks to be

sure that the address Y,A is less than FRETOP.  May cause garbage collection.

Causes "OUT OF MEMORY ERROR" if there's no room.



GARBAG          E484

Move all currently used strings up in memory as far as possible. This

maximizes the free memory area for more strings or numeric variables.



CONT            D898

Moves OLDTXT and OLDLIN into TXTPTR and CURLIN.



NEWSTT          D7D2

Execute a new statement.  On entry TXTPTR points to the ":" preceding the

statement or the zero at the end of the previous line.  Use NEWSTT to restart

the program with CONT.  THIS ROUTINE DOES NOT RETURN.



RUN             D566

Run the program in memory.  THIS ROUTINE DOES NOT RETURN.



GOTO            D93E

Uses LINGET and FNDLIN to update TXTPTR.  GOTO assumes that the 6502 registers

and A have been set up by the CHRGET that fetched the first digit.



LET             DA46

Uses CHRGET to get address of the variable, "=", evaluate the formula, and

store it.  On entry TXTPTR points to the first character of the variable

name.





Apple Tech Notes





Keywords:  <None>



==================================================================



This information is from the Apple Technical Information Library.



ArticleID: TECHINFO-0000080



19960724 15:55:27.00

.