DS200TCTGG1AFF燃机模块,GE产品重量
PCI和SCSISCSI是面向字节流的；中地址最低的字节不管endian模式如何，内存都是第一个要传输的内存。由于Raven ASIC在两个小端都保持地址不变性在大端模式下，SCSI数据不应出现端位问题。Big-endian软件仍然必须考虑字节交换效应然而，当访问PCI/SCSI设备的寄存器时。PCI和以太网以太网也是面向字节流的；具有最低地址的字节在内存中是第一个被传输的，无论端模式如何。
DS200TCTGG1AFF燃机模块因为Raven在little endian和在大端模式下，以太网数据不应出现端问题。
Big-endian软件仍然必须考虑字节交换效应然而，当访问PCI/Ethernet设备的寄存器时。宇宙ASIC的作用由于PCI总线是小端，而VMEbus是大端，因此Universe PCI/VME总线桥ASIC在这两种总线中执行字节交换维护的方向（从PCI到VMEbus和从VMEbus到PCI）地址不变性，与处理器的操作模式无关领域VMEbus域VMEbus本质上是大端的。所有直接连接到的设备VMEbus必须在大端模式下运行，而不管处理器域中的操作。在大端模式下，字节交换首先由Universe执行ASIC和Raven。结果对big endian是透明的软件（理想效果）。然而，在little endian模式下，软件必须进行字节交换ASIC的影响和考虑到乌鸦。介绍本章介绍了MVME2603/2604单板计算机方框图级别。一般说明概述了MVME2603/2604，然后详细描述了电路。图3-1显示了整个电路板的框图建筑学其他MVME2603/2604区块的详细说明，包括ASIC和外围芯片中的可编程寄存器可在附录D中列出的程序员参考指南，与文档有关的功能说明，请参阅MVME2603/2604更深入。特征下表总结了MVME2603/2604的功能单板计算机。
PCI and SCSI
SCSI is byte-stream-oriented; the byte having the lowest address in
memory is the first one to be transferred regardless of the endian mode.
Since the Raven ASIC maintains address invariance in both little-endian
and big-endian modes, no endian issues should arise for SCSI data.
Big-endian software must still take the byte-swapping effect into account
when accessing the registers of the PCI/SCSI device, however.
PCI and Ethernet
Ethernet is also byte-stream-oriented; the byte having the lowest address
in memory is the first one to be transferred regardless of the endian mode.
Since the Raven maintains address invariance in both little-endian and
big-endian mode, no endian issues should arise for Ethernet data.
Big-endian software must still take the byte-swapping effect into account
when accessing the registers of the PCI/Ethernet device, however.
Role of the Universe ASIC
Because the PCI bus is little-endian while the VMEbus is big-endian, the
Universe PCI/VME bus bridge ASIC performs byte swapping in both
directions (from PCI to VMEbus and from VMEbus to PCI) to maintain
address invariance, regardless of the mode of operation in the processor’s
domain.
VMEbus Domain
The VMEbus is inherently big-endian. All devices connected directly to
the VMEbus must operate in big-endian mode, regardless of the mode of
operation in the processor’s domain.
In big-endian mode, byte-swapping is performed first by the Universe
ASIC and then by the Raven. The result is transparent to big-endian
software (a desirable effect).
In little-endian mode, however, software must take the byte-swapping
effect of the Universe ASIC and the address reverse-rearranging effect of
the Raven into account.Introduction
This chapter describes the MVME2603/2604 single board computer on a
block diagram level. The General Description provides an overview of the
MVME2603/2604, followed by a detailed description of several blocks of
circuitry. Figure 3-1 shows a block diagram of the overall board
architecture.
Detailed descriptions of other MVME2603/2604 blocks, including
programmable registers in the ASICs and peripheral chips, can be found in
the Programmer’s Reference Guide, listed in Appendix D, Related
Documentation. Refer to it for a functional description of the
MVME2603/2604 in greater depth.
Features
The following table summarizes the features of the MVME2603/2604
single board computers.
