How an Accident of Hardware Design Encouraged Open Source (O'ReillyNet) [LWN.net]

How an Accident of Hardware Design Encouraged Open Source (O'ReillyNet)

Posted Mar 1, 2007 17:26 UTC (Thu) by jzbiciak (✭ supporter ✭, #5246)
In reply to: How an Accident of Hardware Design Encouraged Open Source (O'ReillyNet) by brouhaha
Parent article: How an Accident of Hardware Design Encouraged Open Source (O'ReillyNet)

Ok, I misremembered then. I didn't have much opportunity to program the 6800 series back in the day--just a few brushes with a 6875 and a 68HC11.

Big endian bit numbering is supremely annoying to me. The TI Home Computer numbered its busses in big-endian. A0 was the MSB of the address bus. Depending on whether you were looking at the 16-bit or 8-bit portion of the bus, the LSB was A14 or A15. (Yes, I did program 9900 assembly. It was my first assembly language.)

It works, but it only works well if you left-justify addresses as opposed to right-justifying them. And that only works if you know what your longest address is. What happens if the machine goes to 32 bits? :-)

(I'll stop now. I had written more, but thought better of it.)

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