Download Vector VEC256 Hardware manual

For Xerox Internal Use Only -- December 15, 1980
Alto Operating System
May 5, 1980
3
e) A 44-key keyboard, 5-finger keyset, and mouse
f) A Diablo printer interface
g) An Ethernet interface
h) Interfaces for analog-to-digital and digital-to-analog conversion, for TV camera input, and for
RS-232b (teletype) connection
a
i) A real-time clock and an interval timer (see table 2.1 for brief descriptions)
3. User-callable procedures
This section describes the operating system facilities provided by procedures which can be called from
programs using the standard Bcpl calling sequence. All of these procedures are a permanent part of
operating system, automatically available to any user program.
user
the
Although this manual describes a rather extensive set of facilities, which together occupy close to
words of memory, portions of the system can be deactivated (see Junta), thus freeing the memory they
When the user program finishes execution, the deactivated portions can be retrieved from the disk
reinitialized.
12K
use.
and
Default arguments: Many of the procedures given below have rather long argument lists, but
convenient defaulting schemes. The documentation decorates argument lists with default values.
argument followed by [exp] will default if omitted or zero to the value exp; an argument followed
[...exp] will default if omitted to exp. Although Bcpl allows you to omit procedure arguments by
"nil," the called procedure cannot detect its use; it therefore cannot be the basis for defaulting arguments.
have
An
by
using
3.1. Facilities
The facilities of the operating system fall into fairly neat categories; often this is because the
operating
system has simply loaded a standard library subroutine as part of its environment. This manual
offers
summarized documentation for the functions in the various software "packages;" more documentation
can
be found in the "Alto Software Packages Manual." (Note: Appendices to this manual
include
documentation of the packages most relevant to the operating system.) In outline, the operating
system
provides:
-
A "basic" resident that maintains a time-of-day clock, that processes parity error interrupts,
that contains the resident required to interface to Swat, the debugger.
and
-
The Bcpl runtime support module, which provides several functions (such as a stack
allocator) that are necessary to permit Bcpl programs to run.
-
Disk drivers for transferring complete pages between memory and existing files on the disk.
is the BfsBase package.
-
Disk drivers for creating new files, and for extending or shortening existing files. This is
BfsWrite package.
-
A simple storage allocator for managing "zones" of working storage. This is the
-
Disk "streams," which implement sequential byte or word I/O to the disk. This is the
package.
-
Disk directory management, which provides facilities for searching directory files for entries
associate a string name and a disk file.
frame
This
the
Alloc package.
DiskStreams
that