These locations are used during the SPRSAV routine [$76EC] to temporarily preserve the current value in the CHRGET pointer (61-62/$3D-$3E).
9 9 4 $ O 3 E 2 FG_BG Standard bitmap color fill value
This location holds the color memory fill pattern for standard bitmapped mode. When the SCNCLR routine [$6A79] is used to clear the standard bitmapped (GRAPHIC 1 or GRAPHIC 2) display, all locations in the video matrix area will be filled with the value here. (The SCNCLR routine is also used when the clear parameter is specified in a GRAPHIC statement.) In standard bitmapped mode, the video matrix area holds fore- ground and background color information, so the value here determines the default foreground and background colors for all screen positions after the screen is cleared.
Whenever the BASIC graphics routines are used to draw anything on the standard bitmapped display, the value in this location will determine the color of the line drawn. If color source 0 was specified for the line, the value in the lower four bits here will be stored in the lower four bits of the video ma- trix locations corresponding to the line's location in the bit- map. If color source 1 is specified, the value in the upper four bits here will be stored in the upper four bits of the video matrix locations corresponding to the line's location in the bitmap.
The value in this location is updated whenever the COLOR statement [$69E2] is executed. The high four bits here are set to the value in the lower four bits of the foreground color in location 134/$86. The lower four bits here are set to the value in the lower four bits of the VIC background color register at 53281/$D021. These locations are initialized during
981
S03D5
981 $03D5 CURRENT-BANK
Bank number for BASIC operationsThe value in this location specifies the bank number used dur- ing BASIC routines which directly access memory. The value here doesn't affect the current system configuration—only the configuration that will be established for certain operations. The value here specifies the bank to which data will stored when the POKE statement is used, or from which data will be read when the PEEK statement is used. The value here deter- mines the bank configuration in which the target address for a SYS statement will be seen. It also determines the bank for the address used in the WAIT statement. The value here deter- mines the default bank for the BOOT, BLOAD, and BSAVE statements. It also determines the system bank affected by the STASH, FETCH, and SWAP statements.
The value here is initialized to 15/$0F during the BASIC cold-start sequence, so bank 15 is the default. The BANK statement can be used to change the value here.
982-985 $03D6-$03D9 TMPDES
Pointers for INSTR evaluationThese locations are used as working pointers for the INSTR statement routine [$99C1]. Locations 982-983/$03D6-$03D7 hold the address of the first string parameter and locations 984-985/$03D8-$03D9 hold the address of the second string.
$03DA
FIN_BANK
986
String block flag
This location is used during the routine [$8D22] to convert character strings into floating-point values to indicate whether the string being converted resides in BASIC program text (block 0 RAM) or in the string pool {block 1 RAM).
987-990 $03DB-$03DE SAVSIZ
Temporary storage for SHAPE dataThese locations are used during the SSHAPE routine [$642B] to hold coordinates of the area being saved, and during the SPRSAV routine [$76EC] to hold the descriptor of the first pa- rameter value.
110
S 0 3 E 2
994
991 $03DF BITS
Floating-point overflow byteThis location is used for working storage while aligning float- ing-point values for mathematical operations, or for converting floating-point values into integers. The value here is initialized to O/$0O during the BASIC cold-start sequence, and will be re- set to that value during CLR or warm start.
992-993 $03E0-$03El SPRTMP
Temporary pointer storageThese locations are used during the SPRSAV routine [$76EC] to temporarily preserve the current value in the CHRGET pointer (61-62/$3D-$3E).
9 9 4 $ O 3 E 2 FG_BG Standard bitmap color fill value
This location holds the color memory fill pattern for standard bitmapped mode. When the SCNCLR routine [$6A79] is used to clear the standard bitmapped (GRAPHIC 1 or GRAPHIC 2) display, all locations in the video matrix area will be filled with the value here. (The SCNCLR routine is also used when the clear parameter is specified in a GRAPHIC statement.) In standard bitmapped mode, the video matrix area holds fore- ground and background color information, so the value here determines the default foreground and background colors for all screen positions after the screen is cleared.
Whenever the BASIC graphics routines are used to draw anything on the standard bitmapped display, the value in this location will determine the color of the line drawn. If color source 0 was specified for the line, the value in the lower four bits here will be stored in the lower four bits of the video ma- trix locations corresponding to the line's location in the bit- map. If color source 1 is specified, the value in the upper four bits here will be stored in the upper four bits of the video matrix locations corresponding to the line's location in the bitmap.
The value in this location is updated whenever the COLOR statement [$69E2] is executed. The high four bits here are set to the value in the lower four bits of the foreground color in location 134/$86. The lower four bits here are set to the value in the lower four bits of the VIC background color register at 53281/$D021. These locations are initialized during
995 S03E3
the BASIC cold-start sequence to the default foreground and background colors, so this location will initially hold 219/$DB, for a light green foreground and dark gray background. The value here is not affected by RUN/STOP-RESTORE.
995 $03E3 FG-JMC1
Multicolor bitmap color fill value
This location holds the color memory fill pattern for multicolor bitmapped mode. When the SCNCLR routine [$6A79] is used to clear the multicolor bitmapped (GRAPHIC 3 or GRAPHIC 4) display, all locations in the video matrix area will be filled with the value here. (The SCNCLR routine is also used when the clear parameter is specified in a GRAPHIC statement.) In multicolor bitmapped mode, the video matrix area holds color information for pixels with %01 and %10 bit patterns, so the value here determines the default colors for those pixel pat- terns in all screen positions after the screen is cleared.
For the BASIC graphics routines that draw on the multi- color bitmapped display, the value in this location will deter- mine the color of any lines drawn using color sources 1 or 2. If color source 1 was specified for the line, the value in the upper four bits here will be stored in the upper four bits of the video matrix locations corresponding to the line's location in the bitmap. If color source 2 was specified, the value in the lower four bits here will be stored in the lower four bits of the video matrix locations corresponding to the line's location in the bitmap.
The value in these locations can be changed with the COLOR statement [$69E2]. The high four bits here are set to the value in the lower four bits of the foreground color in lo- cation 134/$86. The lower four bits here are set to the multi- color 1 value in the lower four bits of location 132/$84. The location is initialized during the BASIC cold-start sequence to the default multicolor pixel colors for %01 and %10 patterns, so this location will initially hold 2O9/$D1, for light green
%01 pixels and white %1O pixels. The value here is not af- fected by RUN/STOP-RESTORE.
996-1007 $03E4-$03EF Unused
The locations in this range are not used by any system ROM routine, and are thus available for your own programming.
112
$03FD-$03FF 1021-1023
1008-1020 $03F0-$03FC DMA
DMA_CALL execution routine
This area holds the RAM-resident portion of the Kernal DMA_CALL routine [$F7A5]. The routine is copied here from Kernal ROM during the reset sequence. It is designed to initi- ate a DMA (direct memory access) command to the REC (RAM expansion controller) chip in an installed memory ex- pansion module. The routine loads the current memory con- figuration register contents, then stores the contents of the Y register in the REC command register address (57089/$DF01) and stores the contents of the accumulator in the MMU mem- ory configuration register (65280/$FF00). If the REC is config- ured in its default state, storing the value in the MMU register should trigger the specified REC operation. See Chapter 8 for more information about the REC chip. Upon completion of the operation, the original memory configuration register setting will be restored.
1021-1023 $03FD-$03FF Unused
The locations in this range are not used by any system ROM routine, and are thus available for your own programming.
995 S03E3
the BASIC cold-start sequence to the default foreground and background colors, so this location will initially hold 219/$DB, for a light green foreground and dark gray background. The value here is not affected by RUN/STOP-RESTORE.
995 $03E3 FG-JMC1
Multicolor bitmap color fill value
This location holds the color memory fill pattern for multicolor bitmapped mode. When the SCNCLR routine [$6A79] is used to clear the multicolor bitmapped (GRAPHIC 3 or GRAPHIC 4) display, all locations in the video matrix area will be filled with the value here. (The SCNCLR routine is also used when the clear parameter is specified in a GRAPHIC statement.) In multicolor bitmapped mode, the video matrix area holds color information for pixels with %01 and %10 bit patterns, so the value here determines the default colors for those pixel pat- terns in all screen positions after the screen is cleared.
For the BASIC graphics routines that draw on the multi- color bitmapped display, the value in this location will deter- mine the color of any lines drawn using color sources 1 or 2. If color source 1 was specified for the line, the value in the upper four bits here will be stored in the upper four bits of the video matrix locations corresponding to the line's location in the bitmap. If color source 2 was specified, the value in the lower four bits here will be stored in the lower four bits of the video matrix locations corresponding to the line's location in the bitmap.
The value in these locations can be changed with the COLOR statement [$69E2]. The high four bits here are set to the value in the lower four bits of the foreground color in lo- cation 134/$86. The lower four bits here are set to the multi- color 1 value in the lower four bits of location 132/$84. The location is initialized during the BASIC cold-start sequence to the default multicolor pixel colors for %01 and %10 patterns, so this location will initially hold 2O9/$D1, for light green
%01 pixels and white %1O pixels. The value here is not af- fected by RUN/STOP-RESTORE.
996-1007 $03E4-$03EF Unused
The locations in this range are not used by any system ROM routine, and are thus available for your own programming.
$03FD-$03FF 1021-1023
1008-1020 $03F0-$03FC DMA
DMA_CALL execution routine
This area holds the RAM-resident portion of the Kernal DMA_CALL routine [$F7A5]. The routine is copied here from Kernal ROM during the reset sequence. It is designed to initi- ate a DMA (direct memory access) command to the REC (RAM expansion controller) chip in an installed memory ex- pansion module. The routine loads the current memory con- figuration register contents, then stores the contents of the Y register in the REC command register address (57089/$DF01) and stores the contents of the accumulator in the MMU mem- ory configuration register (65280/$FF00). If the REC is config- ured in its default state, storing the value in the MMU register should trigger the specified REC operation. See Chapter 8 for more information about the REC chip. Upon completion of the operation, the original memory configuration register setting will be restored.
1021-1023 $03FD-$03FF Unused
The locations in this range are not used by any system ROM routine, and are thus available for your own programming.