I think this is new (sorry if this is old news) but it seems the original source for the Apple II has been released:

http://www.theregister.co.uk/2013/11/12/apple_ii_source_code_released/

The actual good bits are here:

http://www.computerhistory.org/atchm/apple-ii-dos-source-code/

Simon

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My 6502 related blog: http://www.asciimation.co.nz/bb/category/6502-computer

I just saw this, too. Can't wait to find the time to sit down and read it. Then there is this:



This seems to be the IMP-16: http://www.selectric.org/imp16/

Nice find. Thank you, Simon. Those articles bring back many fond memories of that era...

After I purchased an Apple ][ in March, 1979, it took several months to save enough to purchase the Disk ][ drive and controller. I seem to recall the Disk ][ cost around $600 (ouch!) which is remarkable when you consider that many years later you could buy floppy disk drives for ten dollars, or less (grin). Floppy diskettes were pretty expensive too. If I recall correctly, a box of ten Verbatim 5.25 inch diskettes cost around $40 back then. Much more than an active hobbyist with a modest budget could afford so I worked out a trade deal with a couple local computer stores. Basically, I made an Apple ][ Lower Case Generator IC (a 2716 EPROM) which I sold for $40 USD and I would trade diskettes for LCG ICs one for one with the local stores. I never ran out of diskettes (grin).

The listing in that article could have saved me several months work disassembling Apple DOS by hand. When Apple introduced DOS 3.3, which used 16 sectors per track, I wrote a utility that allowed you to switch between the 16 sector and the older DOS 3.1/3.2 13 sector drivers which made it easier for people to move their program and data files onto the newer 16 sector diskettes. A local software startup, Sensible Software (West Bloomfield, MI), picked up the program and marketed it as DOS Plus and it made the Top Ten Best Seller List (Utility category) in SoftTalk Magazine several times. Much later, I contributed DOS and Pascal drivers to Xebec, an SCSI controller manufacturer, which went into the host controller for their Sider hard drives for the Apple ][.

Cheerful regards, Mike