80C186EB/80C188EB Microprocessor User's Manual - CEUNES

PERIPHERAL CONTROL BLOCKRegister Name:Register Mnemonic:Register Function:PCB Relocation RegisterRELREGRelocates the PCB within memory or I/O space.15 0ETMEMR19R18R17R16R15R14R13R12R11R10R9R8A1263-0ABitMnemonicBit NameResetStateFunctionET Escape Trap 0 The ET bit controls access to the math coprocessor.If ET is set, the CPU will trap (resulting ina Type 7 interrupt) when an ESC instruction isexecuted.NOTE: The 8-bit bus version of the deviceautomatically traps an ESC opcode to the Type 7interrupt, regardless of the state of the ET bit.MEM Memory I/O 0 The MEM bit specifies the PCB location. SetMEM to locate the PCB in memory space, orclear it to locate the PCB in I/O space.R19:8 PCB BaseAddressUpper BitsNOTE:0FFHR19:8 define the upper address bits of the PCBbase address. All lower bits are zero. R19:16 areignored when the PCB is mapped to I/O space.Reserved register bits are shown with gray shading. Reserved bits must be writtento a logic zero to ensure compatibility with future Intel products.Figure 4-1. PCB Relocation Register4-2