DS200TCTGG1AFF燃機(jī)模塊,GE產(chǎn)品重量
PCI和SCSISCSI是面向字節(jié)流的；中地址最低的字節(jié)不管endian模式如何，內(nèi)存都是第一個(gè)要傳輸?shù)膬?nèi)存。由于Raven ASIC在兩個(gè)小端都保持地址不變性在大端模式下，SCSI數(shù)據(jù)不應(yīng)出現(xiàn)端位問(wèn)題。Big-endian軟件仍然必須考慮字節(jié)交換效應(yīng)然而，當(dāng)訪問(wèn)PCI/SCSI設(shè)備的寄存器時(shí)。PCI和以太網(wǎng)以太網(wǎng)也是面向字節(jié)流的；具有最低地址的字節(jié)在內(nèi)存中是第一個(gè)被傳輸?shù)模瑹o(wú)論端模式如何。
DS200TCTGG1AFF燃機(jī)模塊因?yàn)镽aven在little endian和在大端模式下，以太網(wǎng)數(shù)據(jù)不應(yīng)出現(xiàn)端問(wèn)題。
Big-endian軟件仍然必須考慮字節(jié)交換效應(yīng)然而，當(dāng)訪問(wèn)PCI/Ethernet設(shè)備的寄存器時(shí)。宇宙ASIC的作用由于PCI總線是小端，而VMEbus是大端，因此Universe PCI/VME總線橋ASIC在這兩種總線中執(zhí)行字節(jié)交換維護(hù)的方向（從PCI到VMEbus和從VMEbus到PCI）地址不變性，與處理器的操作模式無(wú)關(guān)領(lǐng)域VMEbus域VMEbus本質(zhì)上是大端的。所有直接連接到的設(shè)備VMEbus必須在大端模式下運(yùn)行，而不管處理器域中的操作。在大端模式下，字節(jié)交換首先由Universe執(zhí)行ASIC和Raven。結(jié)果對(duì)big endian是透明的軟件（理想效果）。然而，在little endian模式下，軟件必須進(jìn)行字節(jié)交換ASIC的影響和考慮到烏鴉。介紹本章介紹了MVME2603/2604單板計(jì)算機(jī)方框圖級(jí)別。一般說(shuō)明概述了MVME2603/2604，然后詳細(xì)描述了電路。圖3-1顯示了整個(gè)電路板的框圖建筑學(xué)其他MVME2603/2604區(qū)塊的詳細(xì)說(shuō)明，包括ASIC和外圍芯片中的可編程寄存器可在附錄D中列出的程序員參考指南，與文檔有關(guān)的功能說(shuō)明，請(qǐng)參閱MVME2603/2604更深入。特征下表總結(jié)了MVME2603/2604的功能單板計(jì)算機(jī)。
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.
