JKForth : loader

The JKForth Bootloader

The bootloader is extermely primitive, and allows booting only from 720K floppy diskettes. Why? Because that's all my NEC's BIOS supports. Hey, they were very trendy in 1985.

The bootloader is loaded by the PC BIOS at address 0000:7C00. It loads the JKForth kernel from succeeding disk blocks using BIOS calls, and installs it at address 1000:0000. It also initializes the stack pointer to 2000:FFFF. Finally, it locates the address of the Forth entry routine at address 1000:000A in the loaded kernel image, installs the proper segment address (0x1000) at 1000:000C, and executes an indirect jump to the indicated address. At that point the Forth initializer sets up the stack pointers, then begins interpreting Forth code using the address interpreter.

Questions and comments to Joseph Knapka.


asm forth_code hand_compiled_kernel home loader	The JKForth Bootloader The JKForth Bootloader The bootloader is extermely primitive, and allows booting only from 720K floppy diskettes. Why? Because that's all my NEC's BIOS supports. Hey, they were very trendy in 1985. The bootloader is loaded by the PC BIOS at address 0000:7C00. It loads the JKForth kernel from succeeding disk blocks using BIOS calls, and installs it at address 1000:0000. It also initializes the stack pointer to 2000:FFFF. Finally, it locates the address of the Forth entry routine at address 1000:000A in the loaded kernel image, installs the proper segment address (0x1000) at 1000:000C, and executes an indirect jump to the indicated address. At that point the Forth initializer sets up the stack pointers, then begins interpreting Forth code using the address interpreter. Questions and comments to Joseph Knapka.	Last changed: 03-02-06 22:59:50