int e l 10.1 MEMORY / HARDWARE CONFIGURATION This scheme of memory addressing actually permits MCS BASIC-52 to address 96K bytes of memory, 32K of RAM devices, 32K of EPROM/ROM devices and 32K of combined RAM/EPROM/ROM devices. Since /RD and /PSEN are ANDED for addresses from 8000H through 0FFFFH, the 8052AH "looks like" a Von Neumann machine in this address space. The XBY and CBY special function operators will yield the same value when their arguments are between 8000H and 0FFFFH. When the EPROM programming feature in MCS BASIC-52 is used, BASIC assumes that the EPROM to be programmed is addressed starting at location 8000H.
MCS BASIC-52 can only program EPROMS addressed between 8000H and 0FFFFH. When the PROG command is used for the first time, on an erased EPROM, MCS BASIC-52 stores this program beginning at address 8010H. Locations 8000H through 800FH are used to save the baud rate information, plus configuration information. Some suggestions for implementation of the RAM/EPROM mode are shown in figure 2. - 134 -