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System Variables Data Sheet

 These system variables are used in the NC100 Notepad, and it is assumed that they are also used for the NC150 and NC200 machines.

Address Name Size Comments
&B000 copyofmmu0 &01 copy of MMU0 since it's a write-only port.
&B001 copyofmmu1 &01 copy of MMU1 since it's a write-only port.
&B002 copyofmmu2 &01 copy of MMU2 since it's a write-only port.
&B003 copyofmmu3 &01 copy of MMU3 since it's a write-only port.
&B004 gotcontext &01  
&B005 __savepearlmmu &01 Extra variables needed in case not saving context.
&B006 __saveaf &02  
&B008 __savehl &02  
&B00A saveaf &02 To save context, save all the registers...
&B00C savebc &02  
&B00E savede &02  
&B010 savehl &02  
&B012 saveix &02  
&B014 saveiy &02  
&B016 savepc &02  
&B018 savesp &02  
&B01A saveafdash &02  
&B01C savebcdash &02  
&B01E savededash &02  
&B020 savehldash &02  
&B022 savemmu0 &01 ...and the memory state.
&B023 savemmu1 &01  
&B024 savemmu2 &01  
&B025 savemmu3 &01  
&B026 savecritpc &02  
&B028 savecritsp &02  
&B02A savingcontext &01  
&B02B nmimagic &04  
&B02F nmichksums &08 Checksum bytes of first 8 ROMs.
&B037 criticalpc &02 Save PC and SP for recovery from NMI during IRQ.
&B039 criticalsp &02  
&B03B   &50 A small stack which is only used in initialisation. It can't sensibly overlap with anything in case there is an NMI requiring immediate shutdown after saving context. A subsequent power on will have to restore the context.
&B08B initstack    
&B08B diagnostics? &01 Flag used in start-up, non-zero to do diagnostics.
&B08C saveprinstat &01  
&B08D kbdstate1 &0A 1 bit per key: 1=down, 0=up to correspond to the matrix.
&B097 kbdstate2 &0A  
&B0A1 padkeybuf &40  
&B0E1 padnextin &01 Offset into padkeybuf.
&B0E2 padnextout &01  
&B0E3 padbufempty &01 Non-zero if empty.
&B0E4 lastkbdstate &02  
&B0E6 thiskbdstate &02  
&B0E8 caps.state &01 0=off, &FF=on
&B0E9 savecaps &01  
&B0EA justswitchedon? &01  
&B0EB padserbuf &20 Variables above here are preserved after time-out.
&B10B padsernextin &01  
&B10C padsernextout &01  
&B10D padserbufempty &01  
&B10E padserin_xoff &01 Non-zero when XOFF has stopped inward transmission.
&B10F padserout_xoff &01 Non-zero when XOFF has stopped outward transmission.
&B110 disablexonxoff &01 Non-zero to disable software handshake.
&B111 ackirq &01 Set non-zero when ACK interrupt occurs.
&B112 rptdelay &01 Centiseconds.
&B113 rptrate &01 Centiseconds.
&B114 rpttimer &01 Count down timer for key repeat.
&B115 keytorepeat &01 Key number.
&B116 rptkeystates &01 Shift states.
&B117 rtcbuf &0D  
&B124 d.alarmday &06 Alarm day, hour and minute - ready for RTC chip.
&B12A alarmhappened &01 Non zero when alarm has gone off, message pending.
&B12B alarmhappenedgotmsg &01 Non zero when alarm has gone off, got message & pending.
&B12C soundcounter &01 Non-zero if playing a tune.
&B12D soundptr &02 Pointer to array of frequency,duration.
&B12F soundrepcount &01  
&B130 soundrepptr &02  
&B132 poweroffminutes &01 Configured time to power off.
&B133 minutesleft &01  
&B134 minutecounter &02  
&B136 eventhappened &01  
&B137 preservecontext &01 0=return to main screen at power on.
&B138 dontpreservecontext &01 1=don't preserve (diagnostics/battery).
&B139 mainprog &01 6=inbasic, 128=inexternal (foreground program id).
&B13A currentprinter &01 0 for parallel, 1 for serial.
&B13B currentmenu &02 Pointer to current menu.
&B13D wasmenusel &01 After KMWAITCHAR this is 1 if menu used, 0 if not.
&B13E lastsecond &01 Checked to see whether to update the time.
&B13F clockon? &01 Used in Protext, non-zero when clock is enabled.
&B140 sdumpname &04 File names s.a, s.b, s.c and so on - for screen dumps. Force d.workspace to an 8 byte boundary.
&B148 d.workspace &08 For massaged copy of symbol data (for example, inverse/underline).
&B150 d.datebuf &12  
&B162 d.asciitime &0C hh:mm:ss
&B16E currentcfg &4C  
&B1BA g.outstream &01 Bit 0 for screen, 1 for printer, 2 for file.
&B1BB g.h.outfile &02 File handle for charout if bit 2 set.
&B1BD g.pos &01 Current column number (charout).
&B1CE def.fname &0F Name of current file being edited.  First byte not zero if document open (yellow/red goes to edit mode, transfer from addrbook works).
&B1DD def.first &01  
&B1DE d.findinfobuf &24  
&B202 d.row &01 0-based within window.
&B203 d.col &01  
&B204 d.wintop &01  
&B205 d.winleft &01  
&B206 d.winheight &01 Height -1.
&B207 d.winwidth &01 Width -1.
&B208 d.winset? &01 Non-zero if window.
&B209 d.state &01 Bit 7 if inverse on.
&B20A d.rowcount &01  
&B20B d.colcount &01 How many more cols to print on this line.
&B20C &01 Current stream number.
&B20D d.fastpos &02 Needed for quick screen update.
&B20F d.streamwsp &40 8 streams of 8 bytes each.
&B24F d.dateptr &02 Non-null for expanding time/date.
&B251 d.kmcharret &02 Returned character.
&B253 d.kstate &02 Key locks state.
&B255 d.caslocks &01 Shift states set by sticky key press.
&B256 d.sticky &01 Non-zero in sticky key mode.
&B257 d.yellow &01 Low byte of yellow/other key token stored.
&B258 d.calcmode &01 Non-zero if keyboard in calculator mode.
&B259 d.kmexplen &01 Expansion string length.
&B25A d.kmexpptr &02 Expansion string pointer.
&B25C d.expbuffer &02 Address of expansion key buffer.
&B25E d.expbufptr &02 Pointer to free byte.
&B260 d.expbufend &02 Last byte in buffer.
&B2A1 macro_buf &100  
&B3A7     File selector variables...
&B3A7 fs_clicat &01 Non-zero if CAT command, not fsel.
&B3A8 fs_showsizes &01 Non-zero if showing file sizes (pad default=off).
&B3A9 fs_showsys &01 Non-zero if showing system files.
&B3AA fs_curfile &01 Current file number offset from top left.
&B3AB fs_topleftfile &01 File number displayed top left.
&B3AC fs_numcols &01  
&B3AD fs_colwidth &01  
&B3AE fs_numshown &01  
&B3AF fs_maxfiles &01 Max files that can be shown.
&B3B0 fs_handle &02  
&B3B2 fs_numfilerows &01 Rows of files in CAT command.
&B3B3 fs_startlist &02 Start of file list. Zero if doing unsorted list.
&B3B5 fs_startdir &02 Start of directory entries.
&B3B7 fs_endlist &02  
&B3B9 fs_numfiles &01 Number of files in directory.
&B3BA fs_lastshown &01 Last file number currently shown.
&B3BB tickcount &04 32 bit counter needed for basic.
&B3BF ticksleftuntilevent &02  
&B3C1 tickreloadvalue &02  
&B3C3 tickeventpending &01  
&B3C4 countdowntimer &02  
&B3C6 savestream &01  
&B3C7 password &05 Encrypted.
&B3CC pwbuf &05 Clear.
&B3D1 realpwbuf &05 The real password saved for encrypting.
&B3D6 haspassword &01 Non-zero if has password.
&B3D7 passwdlen &01  
&B3D8 passwordlocked &01 Non-zero if locked (disallow soft reset).
&B3D9 editingsecret &01 Non-zero when editing secret file (can't delete it).
&B3DA inmenu? &01 Non-zero when inside menu - macros disabled.
&B3DB macro_count &01  
&B3DC recording? &01  
&B3DD macro_token &02  
&B3DF printfailed &01 Flag set by MCREADYPRINTER.
&B3E0 wasmemoryerr &01  
&B3E1 inprotext &01 Used in file selector, 0=was [Function][L], non-zero=was [Function][2].
1997–2017 Tim Surtell

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