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EPOS - light and fast OS for PDP-11 http://anycpu.org/forum/viewtopic.php?f=9&t=573 |
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Author: | BigEd [ Tue Feb 05, 2019 2:04 pm ] |
Post subject: | EPOS - light and fast OS for PDP-11 |
As seen on the PiDP-11 mail list, in a PDF posted by Stephen Casner: Quote: The 'OS' in the acronym does not stand for Operating System, instead it is the Environment for Processing of Online Speech. This is a real-time kernel plus a nice CLI ("Exec") and multi-process debugger ("MEND") all implemented in Macro-11. EPOS did not support program development tools itself; system and application code was cross-assembled on a PDP-10 running TENEX or compiled with Whitesmiths C (running on RT-11 if I recall correctly). The style of EPOS also followed TENEX, but the file systems it implemented were DOS, RT-11 and Unix V6, with the last being its native file system. It was designed to be as efficient as possible, with a basic context-switch time of 204 μsec on a PDP11/45 with core memory. This allowed each device driver to be implemented as a separate process as well as facilitating multi-process applications. Processes could have separate address spaces or share one. A single process could, in theory, be populated with a full 64KB of I-space and 64KB of D-space, but EPOS never got the chance to run on hardware with more than 256KB of memory. |
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