int e l APPENDIX A 1.1 MEMORY USAGE (Version 1.0) The following list specifies what locations in internal and external memory MCS BASIC-52 uses, and what these locations are used for. This information can largely be regarded as "for your information," but it can be used to do things like alter the pulse width of a EPROM programming pulse, etc. INTERNAL MEMORY ALLOCATION:
LOCATION(S) IN HEX MCS BASIC-52 USAGE 00H THRU 07H "WORKING REGISTER BANK" 08H BASIC TEXT POINTER -- LOW BYTE 09H ARGUMENT STACK POINTER 0AH BASIC TEXT POINTER -- HIGH BYTE 0BH THRU 0FH TEMPORARY BASIC STORAGE 10H READ TEXT POINTER -- LOW BYTE 11H CONTROL STACK POINTER 12H READ TEXT POINTER -- HIGH BYTE 13H START ADDRESS OF BASIC PROGRAM -- HIGH BYTE 14H START ADDRESS OF BASIC PROGRAM -- LOW BYTE 15H NULL COUNT 16H PRINT HEAD POSITION FOR OUTPUT 17H FLOATING POINT OUTPUT FORMAT TYPE 18H THRU 21H NOT USED -- RESERVED FOR USER 22H BITS USED SPECIFICALLY AS FOLLOWS BIT 22.0H SET WHEN "ONTIME" STATEMENT IS EXECUTED BIT 22.1H SET WHEN BASIC INTERRUPT IN PROGRESS BIT 22.2H SET WHEN "ONEX1" STATEMENT IS EXECUTED BIT 22.3H SET WHEN "ONERR" STATEMENT IS EXECUTED BIT 22.4H SET WHEN "ONTIME" INTERRUPT IS IN PROGRESS BIT 22.5H SET WHEN A LINE IS EDITED BIT 22.6H SET WHEN EXTERNAL INTERRUPT IS PENDING BIT 22.7H WHEN SET, CONT COMMAND WILL WORK 23H BITS USED SPECIFICALLY AS FOLLOWS BIT 23.0H USED AS FLAG FOR "GET" OPERATOR BIT 23.1H SET WHEN INVALID INTEGER FOUND IN TEXT BIT 23.2H TEMPORARY BIT LOCATION BIT 23.3H CONSOLE OUTPUT CONTROL, 1 = LINE PRINTER BIT 23.4H CONSOLE OUTPUT CONTROL, 1 = USER DEFINED BIT 23.5H BASIC ARRAY INITIALIZATION BIT BIT 23.6H CONSOLE INPUT CONTROL, 1 = USER DEFINED BIT 23.7H RESERVED - 162 -