Model 100 System Map Part 7 (F5F4-FFEC): Difference between revisions

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F5FCH -  RST 6.5 RAM vector (3)  Used for UART interrupt (Called)
F5FCH -  RST 6.5 RAM vector (3)  Used for UART interrupt (Called)
F5F0H -  Active system signature: warm vs. cold boot


F5FFH -  RST 7.5 RAM vector (3)  Used for Timer interrupt (Called)
F5FFH -  RST 7.5 RAM vector (3)  Used for Timer interrupt (Called)
Line 49: Line 51:


F64FH -  Y coordinate of last graphic point plotted
F64FH -  Y coordinate of last graphic point plotted
F651H -  Flag used during EDITing a BASIC program.
        0, when editing a .DO file,
        1, while editing an entire BASIC program
        255, when editing a specific lines from a BASIC program
F652H -  "ERRTRP" error trap code pointer (2)
F654H -  ??? Some counter related to the token interpreter (1)
F655H -  ??? (2)


F656H -  Power off exit condition switch (0-return control back to  
F656H -  Power off exit condition switch (0-return control back to  
Line 76: Line 88:


F675H -  Output device for RST 20H (0=screen, 1=printer)
F675H -  Output device for RST 20H (0=screen, 1=printer)
F678H -  Start of string buffer for BASIC (2)
F678H -  Start of string buffer for BASIC (2)


Line 84: Line 97:


F680H -  End of statement marker ':' or null
F680H -  End of statement marker ':' or null
F681H -  BASIC tokenized text


F685H -  Start of keyboard buffer used by the keyboard line input  
F685H -  Start of keyboard buffer used by the keyboard line input  
Line 91: Line 106:


F789H -  Function key definition area (128)
F789H -  Function key definition area (128)
F809H -  End of function key definition area


F80AH -  Function key definition area used by BASIC (128)
F80AH -  Function key definition area used by BASIC (128)


F88CH -  End of used RAM for permanent storage (does not include
F88CH -  End of file area, start of paste buffer and/or BASIC variables (2)
        variables, paste buffer, etc.) (2)
 
F897H -  Start of "work area"


F923H -  Seconds (ones)
F923H -  Seconds (ones)
Line 120: Line 137:


F92EH -  Year (tens)
F92EH -  Year (tens)
F92FH -  Timer, decreases from 125 to 0. At zero, time+date copied
        from clock chip to RAM.
F930H -  Timer, decreases from 12 to 1. When 1, byte at $F931
        decreased by 1.
F931H -  Power down counter. When 1, power goes OFF.


F933H -  Seconds (ones)
F933H -  Seconds (ones)
Line 138: Line 163:


F93BH -  Day (0=Sunday, 1=Monday, etc.)
F93BH -  Day (0=Sunday, 1=Monday, etc.)
F93CH -  ??? timer or timer interrupt related (1)


F93DH -  Time for ON TIME interrupt (SSMMHH) (6)
F93DH -  Time for ON TIME interrupt (SSMMHH) (6)
F943H -  ??? other source claims this is COM on/off flag.
        States COM on/off is 1 for ON, 0 for OFF


F944H -  On Com flag (0=off, 255=on)
F944H -  On Com flag (0=off, 255=on)
Line 162: Line 192:
                   3 - Set for invisible file
                   3 - Set for invisible file
           2-3 - Address of file
           2-3 - Address of file
           4-11 - Eight byte filename.  Filename must have extention
           4-11 - Eight byte filename.  Filename must have extension
                 right justified and filename left justified.  Any  
                 right justified and filename left justified.  Any  
                 gaps should be filled with spaces (ex. "ADD.DO"  
                 gaps should be filled with spaces (ex. "ADD.DO"  
                 should be "ADD  DO")
                 should be "ADD  DO")


F99AH Address of current BASIC program not saved (Suzuki) (2)
F962H BASIC file slot
 
F96DH -  TEXT file slot
 
F978H -  TELCOM file slot
 
F979H -  ADDRSS file slot
 
F98EH -  SCHEDL file slot
 
F999H -  Start of "Suzuki" file slot


F9A5H -  Start of Paste buffer (Hayashi) (2)
F99AH -  Pointer to current BASIC program not saved (Suzuki) (2)
 
F9A4H -  Start of "Hayashi" file slot
 
F9A5H -  Start of PASTE buffer ("Hayashi") pointer (2)
 
F9AFH -  Start of "RickY" file slot
        Note: this is the last reserved file slot. All following file
        slots are in the user region. The routine at $20E4, for example,
        starts out pointing to RickY, but immediately adds 11, since it
        is walking the user file area.
 
F9B0H -  Pointer to BASIC program line being edited (unverified) (2)
 
F9BAH -  User file slots 1-19, extends to FA8A
 
FA8BH -  End of directory marker ($FF)


FAACH -  ASCII character last output to printer
FAACH -  ASCII character last output to printer


FAADH -  Label line enable flag (0=not enabled)
FAADH -  Label line enable flag (0 = disabled, non-zero = enabled)


FAAEH -  Contents of port 0A8H
FAAEH -  Contents of port $A8


FAAFH -  Start of IPL filename (8)
FAAFH -  Start of IPL filename (8)
Line 182: Line 238:


FABEH -  Storage for stack pointer on power up/down for continued  
FABEH -  Storage for stack pointer on power up/down for continued  
        program execution after a power down (2)
        program execution after a power down (2)


FAC0H -  Lowest RAM memory address used by system (8000H for a 32k  
FAC0H -  Lowest RAM memory address used by system (8000H for a 32k  
        system) (2)
        system) (2)


FAC9H -  Offset of last RST 38H call
FAC9H -  Offset of last RST 38H call (computed address for RST 7 call)


FAD0H -  Length of last program loaded or saved on tape
FAD0H -  Length of last program loaded or saved on tape (2)


FADAH -  Start of RST 38H vector table (256)
FADAH -  Start of RST 38H vector table (256)


FAE2H -  LCD character output RAM vector for 20H routine.  The address  
FAE2H -  LCD character output RAM vector for 20H routine.  The address  
        at this location is called everytime a character is sent to  
        at this location is called everytime a character is sent to  
        the LCD (note:This routine is called at 4317H). (2)
        the LCD (note:This routine is called at 4317H). (2)


FAE4H -  Printer output RAM vector.  The 2 byte address at this  
FAE4H -  Printer output RAM vector.  The 2 byte address at this  
Line 204: Line 260:
         location is called evertime an EOF function is performed. (2)
         location is called evertime an EOF function is performed. (2)


FB0CH -  TERM F6 RAM vector (2)
FB0CH -  TELCOM TERM mode F6 RAM vector (2)


FB0EH -  TERM F7 RAM vector (2)
FB0EH -  TELCOM TERM mode F7 RAM vector (2)


FB14H -  WIDTH statement RAM vector.  (2)
FB14H -  WIDTH statement RAM vector.  (2)
Line 233: Line 289:


FB64H -  Create/Locate switch for variables used in the main  
FB64H -  Create/Locate switch for variables used in the main  
        evaluation routine (Locate=0, Create>0).
        evaluation routine (Locate=0, Create>0).


FB65H -  Type of last variable used (2-Integer, 3-String, 4-Single  
FB65H -  Type of last variable used (2-Integer, 3-String, 4-Single  
        Precision, 5-Double Precision)
        Precision, 5-Double Precision)


FB67H -  Start address for file buffer area (2)
FB67H -  Start address for file buffer area (2)


FB94H -  Line number of current data statement
FB94H -  Line number of current data statement (2)


FB96H -  0 if no FOR/NEXT loop in progress
FB96H -  0 if no FOR/NEXT loop in progress


FB99H -  Address of last variable assigned via a LET instruction.   
FB99H -  Address of last variable assigned via a LET instruction.   
        This address points to the variable description table as with  
        This address points to the variable description table as with  
        a VARPTR(variable) instruction.
        a VARPTR(variable) instruction. (2)


FB9BH -  Pointer to most recent or currently running line (2).  This  
FB9BH -  Pointer to most recent or currently running line (2).  This  
        address points to the actual text skipping the line number  
        address points to the actual text skipping the line number  
        and spaces.
        and spaces.


FB9DH -  Stack pointer value used by BASIC to reinitialize the stack.   
FB9DH -  Stack pointer value used by BASIC to reinitialize the stack.   
        This memory pointer is updated after each instruction by the  
        This memory pointer is updated after each instruction by the  
        routine at 0804H. (2)
        routine at 0804H. (2)


FB9FH -  Line number of last error (2)
FB9FH -  Line number of last error (2)


FBA1H -  Most recent used or entered line number (2)
FBA1H -  Most recent used or entered line number (2)
FBA3H -  Pointer of where error occured (2)
 
FBA3H -  Pointer to statement where error occurred (2)


FBA5H -  Address of ON ERROR routine (2)
FBA5H -  Address of ON ERROR routine (2)
FBA7H -  Error status flag
        VirtualT disassembly calls this "BASIC program is running flag"
FBA8H -  End of BASIC expression (2)


FBAAH -  Line where last break, END, or STOP occured (2)
FBAAH -  Line where last break, END, or STOP occured (2)


FBACH -  Address where program stoped on last break, END, or STOP (2)
FBACH -  Address where program stopped on last break, END, or STOP (2)


FBAEH -  Pointer to the start of the DO files and end of the BA files.
FBAEH -  Pointer to the start of the DO files (2)
        (2)


FBB0H -  Pointer to the start of CO files (2)
FBB0H -  Pointer to the start of CO files (2)
Line 282: Line 343:


FBBAH -  26 byte table for default variable types declared by the DEF  
FBBAH -  26 byte table for default variable types declared by the DEF  
        statement.  Each entry corresponds to one of the letters  
        statement.  Each entry corresponds to one of the letters  
        A-Z.  The contents of each entry are 2 for an integer, 3 for  
        A-Z.  The contents of each entry are 2 for an integer, 3 for  
        a string, 4 for a single precision number, and 8 for a double  
        a string, 4 for a single precision number, and 8 for a double  
        precision number. (26)
        precision number. (26)


C18H -  Start of FAC1 for single (4) and double (8) precision number
FC18H -  Start of FAC1 for single (4) and double (8) precision numbers
        (8)
        (8)


FC1AH -  Start of FAC1 for integers (2)
FC1AH -  Start of FAC1 for integers (2)
Line 296: Line 357:
FC6BH -  Start of FAC2 for integers (2)
FC6BH -  Start of FAC2 for integers (2)


FC82H -  Maximum number of open files (Maxfiles) (1)
FC82H -  Maximum number of open files (MAXFILES) (1)


FC83H -  Pointer to the 30 byte file number description pointer  
FC83H -  Pointer to the 30 byte file number descriptor pointer  
        table-2.  Each entry of thetable points to the actual file  
        table-2.  Each entry of the table points to the actual file  
        description table (same as VARPTR(#x)).
        descriptor table (same as VARPTR(#x)).


FC8CH -  Pointer to the file description table for the last file used  
FC8CH -  Pointer to the file descriptor table for the last file used  
        (2)
        (2)
 
FC93H -  Filename Buffer #1 of current BASIC program (8)
 
FC9BH -  ??? maybe terminator of Filename buffer #1


FC93H -  Filename of current BASIC program (6)
FC9CH -  Filename Buffer #2 of last program loaded from tape (6 or 8?)


FC9CH Filename of last program loaded from tape (6)
FCA2H ??? (30 bytes)


FCC0H -  Start of alternate LCD character buffer (320)
FCC0H -  Start of alternate LCD character buffer (320)
FD88H -  Scratchpad w/in ALTLCD for Date/Time in ASCII, used by MENU routine,
FD9FH -  End of Date/Time scratchpad
FDD9H -  Scratchpad w/in ALTLCD for filename argument to $5AA6 (CHKDC - 4)
FDE2H -  End of CHKDC-4 filename argument
FDF0H -  Scratchpad w/in ALTLCD for filespec to be check against filespec
        searched for by CHKDC
FDF9H -  End of CHKDC scratchpad


FDFFH -  End of alternate LCD character buffer
FDFFH -  End of alternate LCD character buffer
Line 315: Line 390:
FE00H -  Start of LCD memory (320)
FE00H -  Start of LCD memory (320)


FF40H -  End of LCD memory
FF3FH -  End of LCD memory
 
FF40H -  ??? (2)


FF42H -  XON/XOFF enable flag.  If this byte is 0, XON/XOFFs are not  
FF42H -  XON/XOFF enable flag.  If this byte is 0, XON/XOFFs are not  
        significant for RS232 operations.  If this byte is greater  
        significant for RS232 operations.  If this byte is greater  
        than 0, XON/XOFFs are treated as normal.
        than 0, XON/XOFFs are treated as normal.


FF43H -  RS232 initialization status (0-deactivated, >0- activated)
FF43H -  RS232 initialization status (0-deactivated, >0- activated)


FF44H -  Sound flag (0=on) (1)
FF44H -  Sound flag (0=on, 175=off) (1)


FF45H -  Contents of port 0E8H (1)
FF45H -  Contents of port $E8H (1)
        (called Cassette ON/OFF flag, elsewhere)


FF46H -  Start of 64 character RS232 buffer (64)
FF46H -  Start of 64 character RS232 buffer (64)
FF85H -  End of 64 RS232 buffer


FF86H -  Number of characters in the RS232 buffer (FF46H).  When this  
FF86H -  Number of characters in the RS232 buffer (FF46H).  When this  
        number reaches 40, a control S is automatically sent by the  
        number reaches 40, a control S is automatically sent by the  
        system.
        system.


FF8AH -  Status of control S (1-Control S has been pressed, 0-no  
FF8AH -  Status of control S (1-Control S has been pressed, 0-no  
        control S is active).
        control S is active).


FF8BH -  8155 UART baud rate generator baud rate timer value (2)
FF8BH -  8155 UART baud rate generator baud rate timer value (2)
FF8DH -  RS232 parity control byte (1)


FF8EH -  High or low cassette level trigger flag for 6FDBH (1)
FF8EH -  High or low cassette level trigger flag for 6FDBH (1)
FF8FH -  ??? (1)
FF90H -  Contains a 2 as long as a noncontrol key held down (1)
FF91H -  ??? (6)


FF97H -  8 bits for storing space, del, tab, esc, paste, label, print,  
FF97H -  8 bits for storing space, del, tab, esc, paste, label, print,  
        and enter key recognition.
        and enter key recognition.




F98H -  8 bits for storing function key recognition
FF98H -  8 bits for storing function key recognition
 
FF99H -  ??? (9)


FFA2H -  8 bits for storing shift, ctrl, grph, code, num, and caps  
FFA2H -  8 bits for storing shift, ctrl, grph, code, num, and caps  
        lock.
        lock.


FFAAH -  Number of characters in keyboard buffer.
FFAAH -  Number of characters in keyboard buffer.


FFABH -  Start of keyboard typeahead buffer (32)
FFABH -  Start of keyboard typeahead buffer (64)
FFEAH -  End of keyboard buffer


FFECH -  Start of 5 byte table describing the bit pattern currently  
FFEBH -  ??? (1)
        under the cursor (5)
 
FFECH -  Start of 5 byte bit image of the pattern currently  
        under the cursor (5). Can be used by screen dump routines
</pre>
</pre>
[[Category:Model T Developer Reference]] [[Category:Model 100 System Map]]

Latest revision as of 14:27, 8 April 2009

Origin

This is a derived work of the "Model 100 System Map", Copyright (C) 1985, Robert D. Covington, Systems Information Management Consultants.

Model 100 RAM Memory Map

F5F4H -  Himem (2)

F5F9H -  RST 5.5 RAM vector (3)  Used for BCR interrupt

F5FCH -  RST 6.5 RAM vector (3)  Used for UART interrupt (Called)

F5F0H -  Active system signature: warm vs. cold boot

F5FFH -  RST 7.5 RAM vector (3)  Used for Timer interrupt (Called)

F602H -  RAM vector for TRAP interrupt (3) (1431H)

F62AH -  Option ROM flag (0-no option ROM)

F62BH -  Dial speed (1=10pps, 2=20pps)

F630H -  Start of 8 byte table for each function key status (1=on,
         0=off)

F639H -  Cursor row (1-8)

F63AH -  Cursor column (1-40)

F63BH -  Number of active rows (1-8)

F63CH -  Number of active columns on screen (1-40)

F63DH -  Label line/8th line protect status (0=off)

F63EH -  Scroll disable flag (0-allow scrolling)

F63FH -  Cursor status (0-off, 1-on)

F640H -  Cursor row (1-8)

F641H -  Cursor Column (1-40)

F646H -  ESCape mode flag for RST 20H (0-normal video, not zero-ESCape 
         mode)

F648H -  Reverse video switch (0=off)

F64EH -  X coordinate of last graphic point plotted

F64FH -  Y coordinate of last graphic point plotted

F651H -  Flag used during EDITing a BASIC program.
         0, when editing a .DO file,
         1, while editing an entire BASIC program
         255, when editing a specific lines from a BASIC program

F652H -  "ERRTRP" error trap code pointer (2)

F654H -  ??? Some counter related to the token interpreter (1)
F655H -  ??? (2)

F656H -  Power off exit condition switch (0-return control back to 
        program on power up, 1-return to menu on power up)

F658H -  Full/half duplex switch (0-half duplex)

F65AH -  Auto linefeed on RS232 output switch (0-auto linefeed option 
        off, not zero-automatically send a linefeed after every 
        carriage return)

F65BH -  Start of textual RS232 parameter setting buffer.   This 
        buffer is normally used to store the STAT setting for TELCOM 
        (5)

F660H -  Self modifying address called on CALL statement

F661H -  Address last called (2)

F667H -  Called on OUT statement

F66AH -  Called on INP function

F672H -  Error code of last error

F674H -  Line printer head position

F675H -  Output device for RST 20H (0=screen, 1=printer)

F678H -  Start of string buffer for BASIC (2)

F67AH -  Current executing line number, FFFFH if no program running. 
        (2)

F67CH -  Start of BASIC program pointer (2)

F680H -  End of statement marker ':' or null

F681H -  BASIC tokenized text

F685H -  Start of keyboard buffer used by the keyboard line input 
        routine at 4644H.

F788H -  Current horizontal position of cursor (0-39)

F789H -  Function key definition area (128)
F809H -  End of function key definition area

F80AH -  Function key definition area used by BASIC (128)

F88CH -  End of file area, start of paste buffer and/or BASIC variables (2)

F897H -  Start of "work area"

F923H -  Seconds (ones)

F924H -  Seconds (tens)

F925H -  Minutes (ones)

F926H -  Minutes (tens)

F927H -  Hours (ones)

F928H -  Hours (tens)

F929H -  Date (ones)

F92AH -  Date (tens)

F92BH -  Day code (0=Sunday, 1=Monday, etc.)

F92CH -  Current month (1-12)

F92DH -  Year (ones)

F92EH -  Year (tens)

F92FH -  Timer, decreases from 125 to 0. At zero, time+date copied
         from clock chip to RAM.

F930H -  Timer, decreases from 12 to 1. When 1, byte at $F931
         decreased by 1.

F931H -  Power down counter. When 1, power goes OFF.

F933H -  Seconds (ones)

F934H -  Seconds (tens)

F935H -  Minutes (ones)

F936H -  Minutes (tens)

F937H -  Hours (ones)

F938H -  Hours (tens)

F939H -  Date (ones)

F93AH -  Date (tens)

F93BH -  Day (0=Sunday, 1=Monday, etc.)

F93CH -  ??? timer or timer interrupt related (1)

F93DH -  Time for ON TIME interrupt (SSMMHH) (6)

F943H -  ??? other source claims this is COM on/off flag.
         States COM on/off is 1 for ON, 0 for OFF

F944H -  On Com flag (0=off, 255=on)

F945H -  Address of On Com routine (2)

F947H -  On time flag (0=off, 255=on)

F948H -  Address of on time routine (2)

F94AH -  Function key vector table (24)
           First byte - On/off status
         Next 2 bytes - Vector address

F962H -  Start of RAM directory
        Byte 1 - Directory flags.  A 255 specifies the end of the 
                 directory.
               Bit 7 - Set if valid entry
                   6 - Set for .DO file
                   5 - Set for .CO file
                   4 - Set for ROM file
                   3 - Set for invisible file
           2-3 - Address of file
          4-11 - Eight byte filename.  Filename must have extension 
                 right justified and filename left justified.  Any 
                 gaps should be filled with spaces (ex. "ADD.DO" 
                 should be "ADD   DO")

F962H -  BASIC file slot

F96DH -  TEXT file slot

F978H -  TELCOM file slot

F979H -  ADDRSS file slot

F98EH -  SCHEDL file slot

F999H -  Start of "Suzuki" file slot

F99AH -  Pointer to current BASIC program not saved (Suzuki) (2)

F9A4H -  Start of "Hayashi" file slot

F9A5H -  Start of PASTE buffer ("Hayashi") pointer (2)

F9AFH -  Start of "RickY" file slot
         Note: this is the last reserved file slot. All following file
         slots are in the user region. The routine at $20E4, for example,
         starts out pointing to RickY, but immediately adds 11, since it
         is walking the user file area.

F9B0H -  Pointer to BASIC program line being edited (unverified) (2)

F9BAH -  User file slots 1-19, extends to FA8A

FA8BH -  End of directory marker ($FF)

FAACH -  ASCII character last output to printer

FAADH -  Label line enable flag (0 = disabled, non-zero = enabled)

FAAEH -  Contents of port $A8

FAAFH -  Start of IPL filename (8)

FABAH -  Address where last BASIC list started (2)

FABEH -  Storage for stack pointer on power up/down for continued 
         program execution after a power down (2)

FAC0H -  Lowest RAM memory address used by system (8000H for a 32k 
         system) (2)

FAC9H -  Offset of last RST 38H call (computed address for RST 7 call)

FAD0H -  Length of last program loaded or saved on tape (2)

FADAH -  Start of RST 38H vector table (256)

FAE2H -  LCD character output RAM vector for 20H routine.  The address 
         at this location is called everytime a character is sent to 
         the LCD (note:This routine is called at 4317H). (2)

FAE4H -  Printer output RAM vector.  The 2 byte address at this 
        location is called everytime a character is output to the 
        printer via the routine at 1470H. (2)

FB00H -  EOF function RAM vector.   The 2 byte address at this 
        location is called evertime an EOF function is performed. (2)

FB0CH -  TELCOM TERM mode F6 RAM vector (2)

FB0EH -  TELCOM TERM mode F7 RAM vector (2)

FB14H -  WIDTH statement RAM vector.  (2)

FB1AH -  CRT open routine RAM vector (2)

FB1EH -  CRT output file routine RAM vector (2)

FB20H -  WAND Open routine RAM vector (2)

FB22H -  WAND Close routine RAM vector (2)

FB24H -  WAND Get routine RAM vector (2)

FB26H -  WAND Special I/O routine vector (2)

FB28H -  LOF function routine RAM vector (2)

FB2AH -  LOC function routine RAM vector (2)

FB2CH -  LFILES statement routine RAM vector (2)

FB2EH -  DSKI$ routine RAM vector (2)

FB30H -  DSKO$ routine RAM vector (2)

FB64H -  Create/Locate switch for variables used in the main 
         evaluation routine (Locate=0, Create>0).

FB65H -  Type of last variable used (2-Integer, 3-String, 4-Single 
         Precision, 5-Double Precision)

FB67H -  Start address for file buffer area (2)

FB94H -  Line number of current data statement (2)

FB96H -  0 if no FOR/NEXT loop in progress

FB99H -  Address of last variable assigned via a LET instruction.  
         This address points to the variable description table as with 
         a VARPTR(variable) instruction. (2)

FB9BH -  Pointer to most recent or currently running line (2).  This 
         address points to the actual text skipping the line number 
         and spaces.

FB9DH -  Stack pointer value used by BASIC to reinitialize the stack.  
         This memory pointer is updated after each instruction by the 
         routine at 0804H. (2)

FB9FH -  Line number of last error (2)

FBA1H -  Most recent used or entered line number (2)

FBA3H -  Pointer to statement where error occurred (2)

FBA5H -  Address of ON ERROR routine (2)

FBA7H -  Error status flag
         VirtualT disassembly calls this "BASIC program is running flag"

FBA8H -  End of BASIC expression (2)

FBAAH -  Line where last break, END, or STOP occured (2)

FBACH -  Address where program stopped on last break, END, or STOP (2)

FBAEH -  Pointer to the start of the DO files (2)

FBB0H -  Pointer to the start of CO files (2)

FBB2H -  Pointer to the start of variable table (2)

FBB4H -  Pointer to the start of array table (2)

FBB6H -  Pointer to the start of the systems unused memory (2)

FBB8H -  Address where DATA search will begin on next READ statement 
        (2)

FBBAH -  26 byte table for default variable types declared by the DEF 
         statement.   Each entry corresponds to one of the letters 
         A-Z.   The contents of each entry are 2 for an integer, 3 for 
         a string, 4 for a single precision number, and 8 for a double 
         precision number. (26)

FC18H -  Start of FAC1 for single (4) and double (8) precision numbers 
         (8)

FC1AH -  Start of FAC1 for integers (2)

FC69H -  Start for FAC2 for single (4) and double (8) precision numbers

FC6BH -  Start of FAC2 for integers (2)

FC82H -  Maximum number of open files (MAXFILES) (1)

FC83H -  Pointer to the 30 byte file number descriptor pointer 
         table-2.  Each entry of the table points to the actual file 
         descriptor table (same as VARPTR(#x)).

FC8CH -  Pointer to the file descriptor table for the last file used 
         (2)

FC93H -  Filename Buffer #1 of current BASIC program (8)

FC9BH -  ??? maybe terminator of Filename buffer #1

FC9CH -  Filename Buffer #2 of last program loaded from tape (6 or 8?)

FCA2H -  ??? (30 bytes)

FCC0H -  Start of alternate LCD character buffer (320)

FD88H -  Scratchpad w/in ALTLCD for Date/Time in ASCII, used by MENU routine,
FD9FH -  End of Date/Time scratchpad

FDD9H -  Scratchpad w/in ALTLCD for filename argument to $5AA6 (CHKDC - 4)
FDE2H -  End of CHKDC-4 filename argument

FDF0H -  Scratchpad w/in ALTLCD for filespec to be check against filespec
         searched for by CHKDC
FDF9H -  End of CHKDC scratchpad

FDFFH -  End of alternate LCD character buffer

FE00H -  Start of LCD memory (320)

FF3FH -  End of LCD memory

FF40H -  ??? (2)

FF42H -  XON/XOFF enable flag.  If this byte is 0, XON/XOFFs are not 
         significant for RS232 operations.  If this byte is greater 
         than 0, XON/XOFFs are treated as normal.

FF43H -  RS232 initialization status (0-deactivated, >0- activated)

FF44H -  Sound flag (0=on, 175=off) (1)

FF45H -  Contents of port $E8H (1)
         (called Cassette ON/OFF flag, elsewhere)

FF46H -  Start of 64 character RS232 buffer (64)
FF85H -  End of 64 RS232 buffer

FF86H -  Number of characters in the RS232 buffer (FF46H).  When this 
         number reaches 40, a control S is automatically sent by the 
         system.

FF8AH -  Status of control S (1-Control S has been pressed, 0-no 
         control S is active).

FF8BH -  8155 UART baud rate generator baud rate timer value (2)

FF8DH -  RS232 parity control byte (1)

FF8EH -  High or low cassette level trigger flag for 6FDBH (1)

FF8FH -  ??? (1)

FF90H -  Contains a 2 as long as a noncontrol key held down (1)

FF91H -  ??? (6)

FF97H -  8 bits for storing space, del, tab, esc, paste, label, print, 
         and enter key recognition.


FF98H -  8 bits for storing function key recognition

FF99H -  ??? (9)

FFA2H -  8 bits for storing shift, ctrl, grph, code, num, and caps 
         lock.

FFAAH -  Number of characters in keyboard buffer.

FFABH -  Start of keyboard typeahead buffer (64)
FFEAH -  End of keyboard buffer

FFEBH -  ??? (1)

FFECH -  Start of 5 byte bit image of the pattern currently 
         under the cursor (5). Can be used by screen dump routines