Temporary use for GSHAPE statement. SCALE mode flag. The SYSTEM Vector Most Commodore computers, based on the 6502 or a derivative, have three important vectors located at the very top of the memory map. Alternately, after typing G064, you can simply turn the 1571 off and then on again. Subsequent PRINT# statements referencing logical file If can then write additional data, which gets appended to the end of the file. If no disk drive is specified (d is absent), drive is assumed. Some commercial software pack- ages for the C-128 redirect this vector to point to a memory-clear routine or to a loop that hangs the system. In this case, the only way to recover is to turn the C-128’s power off and then on again.
Registers at $DCOO-$DCOF. CIA #2 Handles serial port, RS-232 Registers at $DD0O-$DD0F. Reserved I/O block. Register #47 is called the keyboard control register. However, the programmer must first find some free RAM and set it aside exclu- sively for zero-page and / or stack usage. However, the 8502 can always access the MMU registers at $FF00-$FF04 no matter what bank is selected. C-128 Architecture and Memory Management 89 The Conf iguratiion Registser The MMU’s configuration register (CR) directly controls the selec- tion of the various RAM, ROM, and I/O blocks.
Temporary storage for 8563 80- column routines. 8563 cursor color before cursor blink occurs. VIC-II raster value for split- screen changeover. The two 6526 CIA (complex interface adapter) chips are located at $DCOO-$DCOF and $DDOO-$DDOF, just as in the C-64. The block $DEOO-$DEFF, called 10 1 , is still reserved by Commodore for future expansion. The selection of ROM or RAM in this space, otherwise occupied by I/O chips, is determined by bits 4 and 5 of the configuration register. Zero-page memory, however, is at a premium because there are only 256 bytes available to this particular addressing mode.