Posted By
JamesC
on 2014-05-24
13:23:06
|  Re: Commodore LCD Emulator
For basic details on the LCD, review the article in Commodore Microcomputers magazine, Mar/April 1985:
http://www.floodgap.com/retrobits/ckb/secret/cbm-clip-lcd1.jpg
http://www.floodgap.com/retrobits/ckb/secret/cbm-clip-lcd2.jpg
BASIC 3.6 includes most of the commands of BASIC 3.5:
1. RLUM() evaluates as a variable, equivalent to RL(0).
2. The COLOR statement gives a SYNTAX ERROR.
3. RCLR (return the current COLOR) gives an UNIMPLEMENTED COMMAND error.
4. EXIT (from a DO loop) is modified to exit BASIC if not currently running in a DO loop. Think of it as a "Quit BASIC" command, with no y/n confirmation.
The function keys along the bottom of the screen can be redefined with the KEY command. 3.6 adds the keyword POPUPS (token FE25), which allow the system's Notepad and Calculator to pop up "over" BASIC.
I also see a hidden keyword USING (token FB). Since it's just before UNTIL and WHILE (tokens FC and FD) I suspect it was intended for a DO loop.
Many BASIC 7.0 keywords are in the LCD's ROM, but there is no code to support them. FAST, SLOW, and QUIT give SYNTAX errors. Interestingly, OFF (token FE24) does not cause any error at all!
The following "FE-token" commands from BASIC 7.0 will cause UNIMPLEMENTED COMMAND errors:
BANK, FILTER, PLAY, TEMPO, MOVSPR, SPRITE, SPRCOLOR, RREG, ENVELOPE, SLEEP, CATALOG, DOPEN, APPEND, DCLOSE, BSAVE, BLOAD, RECORD, CONCAT, DVERIFY, DCLEAR, SPRSAV, COLLISION, BEGIN, BEND, WINDOW, BOOT, WIDTH, SPRDEF, STASH, FETCH, SWAP.
The following "CE-token" commands from BASIC 7.0 will cause UNIMPLEMENTED COMMAND errors:
POT, BUMP, PEN, RSPRPOS, RSPRITE, RSPRCOLOR, XOR, RWINDOW, POINTER.
BASIC program storage starts at $1000. When using GRAPHIC 1 (the only graphic mode supported on the LCD), BASIC moves up to $3000. Since there are no color or luminance tables to maintain, only pixel data, the LCD places its bitmap from $1000-2FFF.
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