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54 lines
1.7 KiB
Markdown
54 lines
1.7 KiB
Markdown
# Incompatible Timesharing System
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[]
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(https://travis-ci.org/PDP-10/its)
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### About ITS
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ITS, the Incompatible Timesharing System, is an operating system for
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the PDP-10 computer family. It was written by hackers at MIT in the
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1960s. The MIT site was shut down in 1990, but enthusiasts continue
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to operate ITS systems to this day.
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### Documentation
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See the [`doc` subdirectory](doc) for documentation.
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### Building it from scratch
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This repository contains source code, tools, and scripts to build ITS
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from scratch.
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1. First, magnetic tape images are created from files in `src` and
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`bin`. There are two bootable tapes, and two tapes with files in
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DUMP backup format.
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2. Then the tapes are used to create a file system on an RP06 disk and
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populate it with a minimal system.
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3. Next, the system is booted from the disk. Source code is loaded
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from tape, and the following programs are rebuilt:
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- MIDAS, the assembler.
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- DDT, debugger and HACTRN user login shell.
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- The ITS monitor (kernel).
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- Exec DDT, standalone debugger.
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- NSALV, standalone file system tool.
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4. The system is restarted, the rebuilt monitor and salvager are
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combined into a new ITS binary, which is then started.
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5. Remaining programs are rebuilt:
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- TECO, editor.
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- DUMP, tape backup and restore.
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- PDSET, set time and date.
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- KSFEDR, manipulate front-end file system.
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- LOCK, shut down system.
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- ATSIGN DEVICE, load device drivers.
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- TCTYP and CRTSTY, terminal handling.
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- PEEK, system monitoring.
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- ARCDEV, transparent file system access to archive files.
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6. Finally, the whole file system is dumped to tape.
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