HONEYWELL 51454363-175模塊，51454363-175產品外觀
磁盤輸入/輸出支持187Bug可以通過與通信啟動磁盤輸入/輸出VMEbus上的智能磁盤控制器模塊。本節包括：? 區塊與扇區? 設備探針功能
? 通過187Bug命令進行磁盤輸入/輸出
? 通過187Bug系統調用進行磁盤輸入/輸出
? 默認控制器和設備參數
? 磁盤輸入/輸出錯誤代碼磁盤支持設施
187Bug中內置的磁盤支持設施包括：? 命令級磁盤操作
HONEYWELL 51454363-175模塊? 磁盤輸入/輸出系統調用（僅通過其中一個陷阱#496說明）供用戶程序使用
? 磁盤參數的定義數據結構參數表參數，例如映射模塊的地址和連接到控制器模塊的設備的類型和數量由187Bug保存在表格中。這些參數的默認值在通電和冷啟動重置時分配，但可以根據需要進行更改在本章后面關于默認參數的部分中進行了描述。
支持的控制器附錄B包含當前支持的控制器列表，如以及每個控制器的默認配置列表。區塊與扇區邏輯塊定義了磁盤設備的信息單元。A.187Bug將磁盤視為劃分為邏輯磁盤的存儲區域阻礙。默認情況下，邏輯塊大小設置為256字節
阻止系統中的設備。塊大小可以在每個基于IOT命令的設備。
該部門將媒體本身的信息單元定義為：由控制器查看。扇區大小因不同而異控制器和特定設備的值可以顯示和使用IOT命令更改。當請求磁盤傳輸時，傳輸的開始和大小以塊為單位指定。187Bug將其轉換為等效值扇區規范，然后將其傳遞給控制器啟動傳輸。如果從塊到扇區的轉換產生如果是分數扇區計數，則返回一個錯誤，并且不返回任何數據轉移。
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.
