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1 files changed, 0 insertions, 28 deletions
| -rw-r--r-- | hello_world/basic_starter.oph | 28 |
diff --git a/hello_world/basic_starter.oph b/hello_world/basic_starter.oph deleted file mode 100644 index b893c08..0000000 --- a/hello_world/basic_starter.oph +++ /dev/null @@ -1,28 +0,0 @@ -; PRG format -; Contains two bytes of header data, address from which -; the rest of the file will be loaded into memory. -; BASIC memory starts at addr 2048, we effectively place "10 SYS 2064" -; and an end of program after it. Then immedately afterwards -; we place our command on addr 2064. -; When BASIC loads up, it runs "10 SYS 2064" and passes up execution there. -; Then, when we return, we get a zero which indicates termination. - -; The starting address is defined by the value (label or alias) "main". -; Since in basic we need to provide a decimal string, but we store a decimal value, we need -; to do this complicated convertion. -.alias main_addr_ch1 '0 + main / 10000 ; 65535 -> 6 -.alias main_addr_ch2 '0 + [main - main / 10000 * 10000] / 1000 ; 65535 -> 65535 - 60000 = 5535 / 1000 = 5 -.alias main_addr_ch3 '0 + [main - main / 1000 * 1000] / 100 ; 65535 -> 65535 - 65000 = 535 / 100 = 5 -.alias main_addr_ch4 '0 + [main - main / 100 * 100] / 10 ; 65535 -> 65535 - 65500 = 35 / 10 = 3 -.alias main_addr_ch5 '0 + main - main / 10 * 10 ; 65535 -> 65535 - 65530 = 5 - -.word $0801 ; Header -- addr 2049 -.org $0801 ; Program Counter - -.scope - .word _eop ; Next line addr (I guess it is used to tell how long the line is?) - .word 10 ; 10 (line of BASIC program) - .byte $9e," " ; SYS 2064 (opcode for SYS and null terminated string) - .byte main_addr_ch1,main_addr_ch2,main_addr_ch3,main_addr_ch4,main_addr_ch5,0 -_eop: .word 0 ; End of program -.scend |