Talk:83Plus:RAM:8447

Stuff:

• Always call Bh before you output. There's no sense in waiting for the LCD to be ready to receive instructions when you are not yet ready to send them.
• Would it be worth adding pages for OS-independent direct calls in addition to B_CALLs? There aren't very many of them.
  • At some point we may even want to document OS-dependent addresses (such as offpage call points.)

FloppusMaximus 14:47, 21 Apr 2005 (PDT)

AFAIK, 000Bh is not OS dependant (I think it's even documented in the 83psysroutines.pdf), so it should be ok to list it. --Aquanight 17:13, 23 Apr 2005 (PDT)

It's not OS-dependent, but on OS 1.12 (and presumably on earlier OS's) it actually just tests an IY bit and returns. (out=11 call=17 bit=20 ret=10 -> 58 cc, which is enough for most LCD drivers when running at 6 MHz.) Thus it destroys the zero flag (as well as sign, parity, subtract, X, Y, I'm not sure about HC.) Presumably when TI's programmers were writing OS 1.13, they were looking for somewhere they could put an LCD delay routine which wouldn't crash if called on 1.12, and noticed that 000B happened to be such a place. FloppusMaximus 18:52, 23 Apr 2005 (PDT)