DS200CTBAG1ADD通用模塊,GE使用產(chǎn)品
PCCchip2提供的接口允許16位CD2401出現(xiàn)在連續(xù)地址；然而，對CD2401的訪問必須是8位或16位。不允許32位訪問。請參閱CD2401數(shù)據(jù)表和MVME197LE、MVME197DP和MVME197SP Single中的PCCCip2章板機程序員詳細(xì)編程參考指南信息
CD2401支持對本地內(nèi)存的DMA操作。因為CD2401不支持中斷VMEbus鎖定條件所需的重試操作，CD2401 DMA控制器不應(yīng)編程為訪問VMEbus。
DS200CTBAG1ADD通用模塊硬件沒有將CD2401限制為板載DRAM。
打印機接口MVME197LE具有與Centronics兼容的打印機接口。打印機接口由PCCCip2提供。請參閱MVME197LE、MVME197DP和MVME197SP單板計算機詳細(xì)編程信息和打印機端口接口連接的圖紙。以太網(wǎng)接口82596CA用于實現(xiàn)以太網(wǎng)收發(fā)器接口。這個82596CA使用DMA操作訪問本地RAM以執(zhí)行其正常操作功能。因為82596CA具有較小的內(nèi)部緩沖區(qū)和VMEbus
如果DMA具有未定義的延遲期，則可能會發(fā)生緩沖區(qū)溢出編程為訪問VMEbus。因此，82596CA不應(yīng)編程為訪問VMEbus。每個MVME197LE模塊都分配了一個以太網(wǎng)站地址。這地址是$08003E2XXXXX，其中XXXXX是唯一的5位數(shù)字分配給板的以太網(wǎng)站地址顯示在連接到VMEbus的標(biāo)簽上P2接頭。此外，包括以太網(wǎng)地址在內(nèi)的八個字節(jié)是存儲在BBRAM的配置區(qū)域中，具有以下兩個字節(jié)：這些設(shè)置為0。也就是說，08003E2xxxx00000存儲在BBRAM中。在地址為$FFFC1F2C，可以讀取上面的四個字節(jié)（08003E2X）。在地址為$FFFC1F30，可以讀取較低的四個字節(jié)（XXXX0000）。提到本章后面將介紹BBRAM、TOD時鐘內(nèi)存映射。這個MVME197LE調(diào)試器能夠檢索或設(shè)置以太網(wǎng)
The interface provided by the PCCchip2 allows the 16-bit CD2401 to appear at
contiguous addresses; however, accesses to the CD2401 must be 8 or 16 bits.
32-bit accesses are not permitted. Refer to the CD2401 data sheet and to the
PCCchip2 chapter in the MVME197LE, MVME197DP, and MVME197SP Single
Board Computers Programmer’s Reference Guide for detailed programming
information.
The CD2401 supports DMA operations to local memory. Because the CD2401
does not support a retry operation necessary to break VMEbus lock conditions,
the CD2401 DMA controllers should not be programmed to access the
VMEbus. The hardware does not restrict the CD2401 to onboard DRAM.
Printer Interface
The MVME197LE has a Centronics-compatible printer interface. The printer
interface is provided by the PCCchip2. Refer to the PCCchip2 chapter in the
MVME197LE, MVME197DP, and MVME197SP Single Board Computers
Programmer’s Reference Guide for detailed programming information and for
drawings of the printer port interface connections.
Ethernet Interface
The 82596CA is used to implement the Ethernet transceiver interface. The
82596CA accesses local RAM using DMA operations to perform its normal
functions. Because the 82596CA has small internal buffers and the VMEbus
has an undefined latency period, buffer overrun may occur if the DMA is
programmed to access the VMEbus. Therefore, the 82596CA should not be
programmed to access the VMEbus.
Every MVME197LE module is assigned an Ethernet Station Address. This
address is $08003E2XXXXX, where XXXXX is the unique 5-nibble number
assigned to the boardThe Ethernet Station Address is displayed on a label attached to the VMEbus
P2 connector. In addition, the eight bytes including the Ethernet address are
stored in the configuration area of the BBRAM, with the two lower bytes of
those set to 0. That is, 08003E2XXXXX0000 is stored in the BBRAM. At an
address of $FFFC1F2C, the upper four bytes (08003E2X) can be read. At an
address of $FFFC1F30, the lower four bytes (XXXX0000) can be read. Refer to
the BBRAM, TOD Clock memory map description later in this chapter. The
MVME197LE debugger has the capability to retrieve or set the Ethernet
