FOXBORO FCM100E以太網(wǎng)模塊
此空間可用于設(shè)置保護(hù)模式PCI到VMEbus窗口（也稱為PCI從屬映像）。BIOS還將在該區(qū)域映射基于PCI的板載NVRAM、計(jì)時(shí)器和看門狗計(jì)時(shí)器。**該空間可以分配為共享內(nèi)存（例如，在基于奔騰處理器的CPU和VMEbus Master之間）。請(qǐng)注意，如果加載了PMC板，則擴(kuò)展BIOS可能位于該區(qū)域/O端口映射與桌面系統(tǒng)一樣，VMIVME-7750包含特殊的輸入/輸出指令，用于訪問(wèn)駐留在I/O尋址空間（與內(nèi)存尋址空間分離且不同）中的I/O外圍設(shè)備。I/O地址空間中的位置稱為端口。當(dāng)CPU解碼并執(zhí)行I/O指令時(shí)，它在線A00至A15上產(chǎn)生一個(gè)16位I/O地址，并用M/I/O控制線識(shí)別I/O周期。因此，CPU包括一個(gè)獨(dú)立的64Kbyte I/O地址空間，它可以作為字節(jié)、字或長(zhǎng)字訪問(wèn)。
This space can be used to set up protected mode PCI-to-VMEbus windows (also referred
to as PCI slave images). BIOS will also map on-board PCI based NVRAM, Timers and
Watchdog Timers in this area.
** This space can be allocated as shared memory (for example, between the Pentium
processor-based CPU and VMEbus Master). Note that if a PMC board is loaded, the
expansion BIOS may be placed in this area./O Port Map
Like a desktop system, the VMIVME-7750 includes special input/output instructions
that access I/O peripherals residing in I/O addressing space (separate and distinct
from memory addressing space). Locations in I/O address space are referred to as
ports. When the CPU decodes and executes an I/O instruction, it produces a 16-bit
I/O address on lines A00 to A15 and identifies the I/O cycle with the M/I/O control
line. Thus, the CPU includes an independent 64 Kbyte I/O address space, which is
accessible as bytes, words or longwords.
