RELIANCE 803430-8S组装模块PLC
内存映射VMIVME-7740的内存映射如表3-1所示。所有系统共享相同的存储器映射，尽管VMIVME-7740的SDRAM小于512 Mbyte，但它不能填满为板上扩展存储器$E0000-$FFFFF 128 Kbyte ROM BIOS$D8018-$DFFFF 32 Kbyte减去24字节NVRAM$D8016-$D8017 2字节板ID寄存器（BID）（0x7740）$D8014-$D8015 2字节VME BERR地址修改寄存器（VBAMR）$D8010-$D8013 4字节VME PERR地址寄存器（VBAR）保留的全部空间$D800E-$D800F 2字节系统命令寄存器（COMM）$D8000-$D800 D 14字节RTC/看门狗定时器控制寄存器$C8000-$D7FFF 64 KB LANWorks BIOS$C0000-$C7FFF 32 KB视频ROM$A0000-$BFFFF 128 KB视频RAM$00000-$9FFFF 640 KB用户RAM/DOS RAM此空间可用于设置保护模式PCI到VMEbus窗口（也称为PCI从属映像）。**该空间可以分配为共享内存（例如，在基于奔腾III处理器的CPU和VMEbus Master之间）。请注意，如果加载了PMC板，扩展BIOS可能会放在该区域。
Memory Map The memory map for the VMIVME-7740 is shown in Table 3-1. All systems share this same memory map, although a VMIVME-7740 with less than the full 512 Mbyte of SDRAM does not fill the entire space reserved for On-Board Extended Memory $E0000 - $FFFFF 128 Kbyte ROM BIOS $D8018 - $DFFFF 32 Kbyte minus 24 bytes NVRAM $D8016 - $D8017 2 bytes Board ID Register (BID) (0x7740) $D8014 - $D8015 2 bytes VME BERR Address Modifier Register (VBAMR) $D8010 - $D8013 4 bytes VME BERR Address Register (VBAR) $D800E - $D800F 2 bytes System Command Register (COMM) $D8000 - $D800D 14 bytes RTC/Watchdog Timer Control Registers $C8000 - $D7FFF 64 Kbyte LANWorks BIOS $C0000 - $C7FFF 32 Kbyte Video ROM $A0000 - $BFFFF 128 Kbyte Video RAM $00000 - $9FFFF 640 Kbyte User RAM/DOS RAM This space can be used to set up protected mode PCI-to-VMEbus windows (also referred to as PCI slave images). ** This space can be allocated as shared memory (for example, between the Pentium III processor-based CPU and VMEbus Master. Note that if a PMC board is loaded, the expansion BIOS may be placed in this area.
