The BBC and Master Computer Public Domain Library
8F7D NEW
Submitted by Steve Fewell
Description:
Call routine &9BA6 to check that the BASIC statement is correct and ends correctly
-
Call routine &BEFE to carry out the NEW command as follows:
- * Set TOP (&12-&13) to PAGE (&18, LSB of PAGE is always zero)
- * Set TRACE flag (&20) to 0 (meaning that TRACE is OFF)
- * Store #&0D as the first byte of the program, i.e. the '<cr>' character
- * Store #&FF as the second byte of the program (previously this byte contained the line number MSB value)
- These 2 characters specify a null program ('<cr>' specifies program start and #&FF specifies program end)
- * Set TOP to point to the next byte after these two characters
- * Set TRACE flag (&20) to 0 (meaning that TRACE is OFF)
execute any entered commands.
Disassembly for the NEW routine
| 8F7D | 032 166 155 | 20 A6 9B | JSR &9BA6 Check end of Statement | |
| 8F80 | 032 254 190 | 20 FE BE | JSR &BEFE reset the program to an empty program | |
| 8F83 | ... Prompt for command line and execute the entered command(s) ... |
&BEFE - reset the program to an empty program
| BEFE | 169 013 | A9 0D | LDA#&0D | |
| BF00 | 164 024 | A4 18 | LDY &18 | |
| BF02 | 132 019 | 84 13 | STY &13 | |
| BF04 | d | 100 018 | 64 12 | STZ &12 |
| BF06 | d | 100 032 | 64 20 | STZ &20 |
| BF08 | 146 018 | 92 12 | STA (&12) | |
| BF0A | 169 255 | A9 FF | LDA#&FF | |
| BF0C | 160 001 | A0 01 | LDY#&01 | |
| BF0E | 145 018 | 91 12 | STA (&12),Y | |
| BF10 | 200 | C8 | INY | |
| BF11 | 132 018 | 84 12 | STY &12 | |
| BF13 | ` | 096 | 60 | RTS |
