Comment by FarmerPotato

The primary virtue of a Forth system is that it is interactive. You can see this on any 1990s system that can start up in Open Firmware.

I've started with a FIG-Forth kernel in 9900 assembler, which fits into 8K. Many authors worked that code up to the 1990s branch I grabbed.

To bring up the board, I cross-assemble to produce two Flash EEPROMs, plug them in, and power up. The Forth kernel looks at block 6 for customizations where I tell it to compile some source packages I want from Flash. One of these is -ASSEMBLER, which lets me create short chunks of native machine code to work on very low-level things like bit I/O, the SPI and I2C peripheral behavior. Very good for debugging initial hardware.

When I'm happy with some code, I add the source to the next EEPROM build.

Block numbers were originally 1K chunks of disk, but can refer to any kind of storage like pages of ROM/RAM, or even to a process' virtual address space.