xerox Trident Disk Software Oct77 free download

File name Trident_Disk_Software_Oct77.pdf

(ALTODOCS)TFS.TTY;9 FRI 28-0CT-77 11:35AM PAGE 1 For Xerox Internal Use Only -- October 28, 1977 Trident disk software October 21, 1977 1 Software and Utilities for Trident Disks: Tfs, Tfu, Triex 1. Introduction This document describes Bcpl-based software for operating any of the family of Trident disk drives attached to an Alto using a "Trident controller card" (the software presently deals with the T-80 and T-300 models). Hardware and diagnostic information can be found in the document "Trident disk for the Alto" (on (ALTODOCS)TRIDENT.EARS). by Roger Bates. The software documentation is divided into three parts: (1) a brief "how-to" section describing the software package available for operating the Trident; (2) a section describing two useful utility programs. Tfu and Triex; and (3) a section describing the software package in more detail. There is a short revision history at the end. The Tfs package and utilities all assume that the disk is to be formatted with 9 sectors per track, 1024 data words per sector. Thus a T-80 disk has a capacity (815 tracks, 5 surfaces, 9 sectors, 1024 words per sector) of 36,675 pages or 37,555,200 words. A T-300 (19 surfaces rather than 5) has a capacity of 139,365 pages or 142,709,760 words; however, due to the restriction of virtual disk addresses to 16 bits, a single file system may utilize only about 47 percent of this capacity, and it is necessary to construct multiple file systems in order to make use of the entire disk. Because of bandwidth limitations, it is unwise to operate the Trident disk while the Alto display is on. Although the Tfs package will save the display state, turn it off, run the disk, and restore the display for every transfer, the user may prefer to turn the display off himself. The Tfs management of the display causes the screen to flash objectionably whenever frequent calls to Tfs are underway. 2. Trident File System (Tfs) software package The software for operating the Trident disk is contained in (Alto)Tfs.Dm, and consists of the following relocatable files: Tfslnit.Br, TfsBase.Br, TfsA.Br, TfsWrite.Br TfsCreate.Br, TfsClose.Br, TfsDDMgr.Br, TfsNewDisk.Br, TfsSwat.Br. and TriConMc.Br. The definitions file Tfs.D is also included. The LoadRam.Br file, formerly included as part of the Tfs, is now available as a separate package. (ALTODOCS)TFS.TTY;9 FRI 28-0CT-77 11:35AM PAGE 1