NEC 78K/0 Series User Manual

Also see for 78K/0 Series: User manual User manual User manual User manual User manual

Contents

NEC 78K/0 Series User Manual Manual pdf 12 page image

12 User's Manual U12326EJ4V0UMCHAPTER 1 MEMORY SPACE1.1 Memory SpacesThe 78K/0 Series product program memory map varies depending on the internal memory capacity. For detailsof memory-mapped address area, refer to the user’s manual of each product.1.2 Internal Program Memory (Internal ROM) SpaceEach 78K/0 Series product has internal ROM in the address space. Program and table data, etc. are storedin the ROM. Normally, this memory space is addressed by the program counter (PC). For details of the internalROM space, refer to the user’s manual of each product.1.3 Vector Table AreaThe 64-byte area 0000H to 003FH is reserved as a vector table area. The program start addresses for branchupon RESET input or interrupt request generation are stored in the vector table area. Of the 16-bit address, thelower 8 bits are stored at even addresses and the higher 8 bits are stored at odd addresses. For the vector tablearea, refer to the user’s manual of each product.1.4 CALLT Instruction Table AreaThe 64-byte area 0040H to 007FH can store the subroutine entry address of a 1-byte call instruction (CALLT).1.5 CALLF Instruction Entry AreaThe 2048-byte area 0800H to 0FFFH can perform a direct subroutine call with a 2-byte call instruction (CALLF).1.6 Internal Data Memory (Internal RAM) Space78K/0 Series products incorporate the following RAMs. For details of these RAMs, refer to the user’s manualof each product.(1) Internal high-speed RAMEach 78K/0 Series product incorporates an internal high-speed RAM. In the 32-byte area FEE0H to FEFFHof these areas, 4 banks of general-purpose registers, each bank consisting of eight 8-bit registers, areallocated.The internal high-speed RAM can also be used as a stack memory.(2) Buffer RAMThere are some products in the 78K/0 Series to which buffer RAM is allocated. This RAM is used to storethe transfer/receive data of serial interface channel 1 (3-wire serial I/O mode with automatic transfer/receivefunction). If not used in this mode, the buffer RAM can also be used as an ordinary RAM area.