int e l 3.1 DESCRIPTION OF EPROM FILE COMMANDS COMMANDS: RAM(cr) and ROM [integer] (cr) ACTION TAKEN: These two commands tell the MCS BASIC-52 interpreter whether to select the current program (the current program is the one that will be displayed during a LIST command and executed when RUN is typed) out of RAM or EPROM. The RAM address is assumed to be 512 (200H) and the EPROM address begins at 32784 (8010H). RAM When RAM(cr) is entered MCS BASIC-52 selects the current program from RAM MEMORY. This is usually considered the "normal" mode of operation and is the mode that most users interact with the command interpreter.
ROM When ROM [integer] (cr) is entered MCS BASIC-52 selects the current program out of EPROM memory. If no integer is typed after the ROM command (i.e. ROM (cr)) MCS BASIC-52 defaults to ROM 1. Since the programs are stored sequentially in EPROM the integer following the ROM command selects which program the user wants to run or list. If you attempt to select a program that does not exist (i.e. you type in ROM 8 and only 6 programs are stored in the EPROM) the message ERROR: PROM MODE will be displayed. MCS BASIC-52 does not transfer the program from EPROM to RAM when the ROM mode is selected. So, you cannot EDIT a program in the ROM mode.
If you attempt to edit a program in the ROM mode, by typing in a line number, the message ERROR: PROM MODE will be displayed. The following command to be described, XFER, permits one to transfer a program from EPROM to RAM for editing purposes. Since the ROM command does NOT transfer a program to RAM, it is possible to have different programs in ROM and RAM simultaneously. The user can "flip" back and forth between the two modes at any time. Another added benefit of NOT transferring a program to RAM is that all of the RAM memory can be used for variable storage if the PROGRAM is stored in EPROM. The SYSTEM CONTROL VALUES --MTOP and FREE always refer to RAM not EPROM. VARIATIONS: None. - 21 -