I would say bit by bit, I mean "small part" and then keep making small extensions to the program(s)
First for new hardware would be a monitor program.
Either write one, or port one from other hardware.
A monitor program allows the inspection and edit of memory data and also to run programs in such memory.
The monitor program often placed in ROM for convenance.
A 6502 cross assembler, could be used to avoid the need for hand assembly the program to 6502 machine code.
Probably where WOZMON came from.
Then using WOZMON start writing a VERY simple basic interpreter.
Maybe the monitor program was borrowed from other hardware that used a 6502 ( would need slight mods for the Apple 1 ) NOTE This is just a possibility - I actually have NO idea
I suspect WOZ would have invented his own in any case ...
(OFF TOPIC - I messed around with a 68008 chip in mid 1980s?? and I recall I found a book with a complete montor program in for this chip - I can not recall the name of the book. )
Wow, cool to see the 68008 mentioned here! I actually went through 'The Art of Electronics Student Manual Hayes, Thomas C.; Horowitz, Paul' when I was a teenager in the late 90s and the course included wiring up the 68008 into a breadboard and attaching a keypad to key in hand-assembled hex! That was so fun.
I actually wire wrapped the 68008 chip with some buffer chips on a Apple 2 wire wrapping protoyping board. From recollection (<< probably wrong) the 68008 chip was enormous - about 10cm long and 2cm? wide. Back in the 80s I dreamed of getting the DTACK grounded 68000 board advertised in Byte Magazine ... but it was always "..a bit expensive for me ..."
First for new hardware would be a monitor program. Either write one, or port one from other hardware. A monitor program allows the inspection and edit of memory data and also to run programs in such memory. The monitor program often placed in ROM for convenance. A 6502 cross assembler, could be used to avoid the need for hand assembly the program to 6502 machine code.
Probably where WOZMON came from.
Then using WOZMON start writing a VERY simple basic interpreter.
Maybe the monitor program was borrowed from other hardware that used a 6502 ( would need slight mods for the Apple 1 ) NOTE This is just a possibility - I actually have NO idea I suspect WOZ would have invented his own in any case ...
(OFF TOPIC - I messed around with a 68008 chip in mid 1980s?? and I recall I found a book with a complete montor program in for this chip - I can not recall the name of the book. )