HONEYWELL 51454363-175模塊，51454363-175產(chǎn)品外觀
磁盤輸入/輸出支持187Bug可以通過與通信啟動(dòng)磁盤輸入/輸出VMEbus上的智能磁盤控制器模塊。本節(jié)包括：? 區(qū)塊與扇區(qū)? 設(shè)備探針功能
? 通過187Bug命令進(jìn)行磁盤輸入/輸出
? 通過187Bug系統(tǒng)調(diào)用進(jìn)行磁盤輸入/輸出
? 默認(rèn)控制器和設(shè)備參數(shù)
? 磁盤輸入/輸出錯(cuò)誤代碼磁盤支持設(shè)施
187Bug中內(nèi)置的磁盤支持設(shè)施包括：? 命令級磁盤操作
HONEYWELL 51454363-175模塊? 磁盤輸入/輸出系統(tǒng)調(diào)用（僅通過其中一個(gè)陷阱#496說明）供用戶程序使用
? 磁盤參數(shù)的定義數(shù)據(jù)結(jié)構(gòu)參數(shù)表參數(shù)，例如映射模塊的地址和連接到控制器模塊的設(shè)備的類型和數(shù)量由187Bug保存在表格中。這些參數(shù)的默認(rèn)值在通電和冷啟動(dòng)重置時(shí)分配，但可以根據(jù)需要進(jìn)行更改在本章后面關(guān)于默認(rèn)參數(shù)的部分中進(jìn)行了描述。
支持的控制器附錄B包含當(dāng)前支持的控制器列表，如以及每個(gè)控制器的默認(rèn)配置列表。區(qū)塊與扇區(qū)邏輯塊定義了磁盤設(shè)備的信息單元。A.187Bug將磁盤視為劃分為邏輯磁盤的存儲(chǔ)區(qū)域阻礙。默認(rèn)情況下，邏輯塊大小設(shè)置為256字節(jié)
阻止系統(tǒng)中的設(shè)備。塊大小可以在每個(gè)基于IOT命令的設(shè)備。
該部門將媒體本身的信息單元定義為：由控制器查看。扇區(qū)大小因不同而異控制器和特定設(shè)備的值可以顯示和使用IOT命令更改。當(dāng)請求磁盤傳輸時(shí)，傳輸?shù)拈_始和大小以塊為單位指定。187Bug將其轉(zhuǎn)換為等效值扇區(qū)規(guī)范，然后將其傳遞給控制器啟動(dòng)傳輸。如果從塊到扇區(qū)的轉(zhuǎn)換產(chǎn)生如果是分?jǐn)?shù)扇區(qū)計(jì)數(shù)，則返回一個(gè)錯(cuò)誤，并且不返回任何數(shù)據(jù)轉(zhuǎn)移。
Disk I/O Support
187Bug can initiate disk input/output by communicating with
intelligent disk controller modules over the VMEbus.
This section covers:
? Blocks Versus Sectors
? Device Probe Function
? Disk I/O via 187Bug Commands
? Disk I/O via 187Bug System Calls
? Default 187Bug Controller and Device Parameters
? Disk I/O Error Codes
Disk Support Facilities
Disk support facilities built into 187Bug consist of the following:
? Command-level disk operations
? Disk I/O system calls (only via one of the TRAP #496
instructions) for use by user programs
? Defined data structures for disk parameters
Parameter Tables
Parameters such as the address where the module is mapped and
the type and number of devices attached to the controller module
are kept in tables by 187Bug. Default values for these parameters
are assigned at powerup and cold-start reset, but may be altered as
described in the section on default parameters, later in this chapter.
Supported Controllers
Appendix B contains a list of the controllers presently supported, as
well as a list of the default configurations for each controller. Blocks Versus Sectors
The logical block defines the unit of information for disk devices. A
disk is viewed by 187Bug as a storage area divided into logical
blocks. By default, the logical block size is set to 256 bytes for every
block device in the system. The block size can be changed on a per
device basis with the IOT command.
The sector defines the unit of information for the media itself, as
viewed by the controller. The sector size varies for different
controllers, and the value for a specific device can be displayed and
changed with the IOT command.
When a disk transfer is requested, the start and size of the transfer
is specified in blocks. 187Bug translates this into an equivalent
sector specification, which is then passed on to the controller to
initiate the transfer. If the conversion from blocks to sectors yields
a fractional sector count, an error is returned and no data is
transferred.
