Normal RSTS/E system operation requires certain system files under the system files account [0,1]. The DSKINT option creates the system files account and two system files (BADB.SYS and SATT.SYS) required on all disks. When DSKINT is used to initialize a system disk, a third system file (RSTS.CIL) is also created to map the RSTS/E Core Image Library. The remaining system files are created by the REFRESH option of the Initialization code.
Table 3-3 lists the system files with a brief description of each. An overview of the REFRESH option is included below to empha-size the importance of using the option to full advantage when the system disk is first built. Detailed discussions of each system file is then presented to provide background information for proper use of the option. Finally, the details of using REFRESH are presented with several examples.
Initialization Options
System or swapping Required disk only
System or swapping Optional disk only CRASH.SYS System disk only Optional
Description
Initialization Options
3.4.1 REFRESH Option Overview
The REFRESH option allows the system manager to create, modify, reposition, and, in some cases, delete system files stored under the system files account [~,l]. The system files reside ori the system disk or on auxiliary swapping disks. (In either case, these files are catalogued by the directory for account [~, 1] on the system disk.) The REFRESH routines assume that the system disk contains at least the minimum RSTS/E file structure as written during the initialization of the system disk using the DSKINT option. The REFRESH operation verifies that the entire disk structure is intact, but only the files stored under account [~,l] are manipulated. Thus, i t is possible to refresh a system disk which contains many files and accounts with-out destroying the existing files.
The REFRESH option must be used to initially create the required system files. This is done immediately after the system disk is initialized with DSKINT and all patches have been installed. Proper use of REFRESH when the system disk is created ensures that changes can be made to the system files at a later date.
Before REFRESH is used, the system manager must understand the principles in the construction of the system disk. The logical structure of the system disk is such that a linear string of unallo-cated space exists on the disk prior to loading the elL. When the
RSTS/E elL is written on the system disk, i t occupies the lower physical portion of the disk. Initializing the system disk writes a minimum RSTS/E file structure on the disk and assimilates the pure code of the eIL into the minimum file structure.
If the hardware includes ·0Re or more swapping disks, these
devices are considered logical extensions of the system disk. Figure 3-1 shows how disk sectors are numbered for several possible system and swapping disk configurations. Swapping disks do not require a file structure or directory information to be on the disk. All such information is included in the directories on the system disk. To allocate space for system files on the swapping devices, the initiali-zation code temporarily extends the system disk storage allocation
4
Initialization Options
out to the system disk, the allocation table does not map any space on the swapping disks regardless of whether the space is free or allocated. REFRESH allocates space on swapping devices based on cal-culated sizes of configured swapping disks. The physical devices are never accessed during REFRESH. Hence the swapping disks need not be physically present for normal REFRESH operation.
The size of RCll and RFll swapping disks vary depending on the number of platters. Each RC platter is 64K words or 256 segments;
Each RF platter is 256K words or 1024 segments. RFll and RCll disks are considered one unit regardless of the number of platters. Hard-ware permits data transfers to continue across these boundaries. The total space available is the sum of the platters sizes. RSTS/E sup-ports the hardware maximum or eight RF platters or four RC platters.
RS03 and RS04 fixed-head disks are treated as separate units.
The system files must fit on a unit and may not cross unit bound-aries. Each RS03 is 256K words or 1024 segments; each RS04 is 5l2K words or 2048 segments. If a system contains both RS03s and RS04s, all RS04s logically follow the system disk and all RS03s follow the RS04s. Physical unit numbers need not be known to use REFRESH.
Physical-to-logical unit mapping is done at Start up time. These distinctions are important when trying to locate system files on particular RS units. RSTS/E supports only four RS disk units for swapping but additional units may be attached to the RHll controller for use by other operating systems.
If the REFRESH operation proceeds without the system manager's requirements, only required system files are created on the system disk. These files are allocated the minimum required storage space in disk sectors immediately following the space occupied by the CIL.
A typical representation appears as follows:
Physical Sector
Boot-strap
1
MFO[l,l]
UFO[O,l]
UFO[1,2]
48 49
RSTS/E CIL 289
BUFF.SYS SWAP.0'.SYS
i
Unallo-cated SpaceInitialization Options
Such distribution of the required system files is seldom optimal.
For example, the default size of SWAP~.SYS can handle only the con-figured number of jobs at the default size of 8K words. Most RSTS/E systems wifl run BASIC-PLUS programs larger than 8K. Furthermore, REFRESH locates all the system files on the system disk, any swapping disks are not used.
At the time the system manager builds the system disk, he has available all the contiguous unallocated storage space. If he does not use this file space, he may be limited by the existing structures at a later time, since time sharing operations cause storage space on the system disk to be allocated randomly on an as-needed basis.
The free contiguous space at the front portion of the system disk can be allocated to user and system program and data files, thus limiting and restricting later structural changes to the system files in
account [O,lJ on the system disk.
A few examples can show the significance of fully using
REFRESH. The RSTS.CIL file is created at the minimum required size during the DSKINT process. (The minimum required size is actually rounded up to span an integral number of disk clusters, as deter-mined by the pack cluster size.) The contiguous storage space at the lower portion of the system disk immediately following the RSTS.CIL file is allocated to whatever other system files are created by REFRESH. During time sharing operations, subsequent contiguous
storage space is allocated to user and system program and data files.
Future expansion of storage space occupied by CIL becomes restricted.
If the system manager wishes to augment the system at some future date with either new hardware or software features, the size of the CIL will necessarily increase by an undetermined amount. The probability of successfully incorporating a newly generated CIL into an existing file structure is greatly improved if the system manager increases the size spanned by the CIL when the system files are
initially built on the system disk. The REFRESH option provides this capability. Thus, to allow for future changes, the system manager specifies from 20 to 40 extra blocks for the RSTS.CIL file. The extra contiguous space is then allocated to the CIL file at the lower portion of the disk, allowing for possible future, successful