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Master Dictionary
(in memory)
Areal
Area
n
The following rules apply:
Physical
Devi ce (pock or RAD)
/
/
/
/
/
r - -
\
\
\
\
/
/
/
r - -
-
~
...
\
\
Areal
Lobel
First Fi Ie
Directory Entry
f-- -
-
- - - -
Entry a
r - - - - - - -
Entry b
~------
File
a
File
b
Areal File
Directory
•
A physical device (e.g., a RAD) may contain 1 to 40 areas. An area is totally contained on
one physical device.
•
An area may contain one or more files. A file is totally contained within one area.
Figure 3. RBM Disk File Management
sufficient spare entries must be available in the Master
Dictionary to accommodate the newly mounted areas, and
the areas to be mounted must be uni que Iy named among
those areas already mounted. RBM performs the necessary
checks to ensure proper mounting.
Special precaution must be taken for 7252 and 3233 Car-
tridge Disk units. Since the fixed disk as well as the re-
movable disk is stopped when replacing the cartridge, at!
file activity must
be
quiesced for both the fixed and re-
movable portions of the device (which are independently
addressable). If RBM's SP area resides on the fixed disk,
the computer must be placed in a completely idle state
(no active background or foreground, no key-ins pending).
Failure to do so will result in a SYSERR with code SP when
on attempt is mode by RBM to access an overlay.
Fore-
ground tasks that access files on the fixed portion of a drive
may also require the computer to
be
in the idle state to
avoid the Inonoperational l condition.
Obviously a crit-
ical real-time environment cannot tolerate the computer
being in lidle I, therefore, proper allocation of areas and
spindles is essential (e.g., two 7251 devices may be re-
qu ired rather than a single 7252).
8
Peripheral Equipment Requirements and Options
PERIPHERAL EQUIPMENT REQUIREMENTS AND OPTIONS
KEYBOARD/PRINTER - REQUIRED
RBM requires that the minimum configuration include a
keyboard/printer for operator control.
If an installation is configured with two or more keyboard/
printers, it is strongly suggested that OF N 1, which must
reference a keyboard/printer, pointat the same printer used
for background operations. Foreground tasks that reference
a keyboard/printer should not reference the keyboard/printer
associated with OF N
t.
CHARACTER-ORIENTED COMMUNICATIONS (COC)-
OPTIONAL
•
One buffered input/output channel dedicated to a
7630 Controller, with eight lines.
•
External DIO interface feature (Model 4170 for
Xerox 530, Model 8170 for Sigma 3).
•
Two external interrupts dedicated to the
cac
controller.
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