JPEG Image - 635.61 kB - 10/01/2020 at 21:54

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prototype0b-hardware.mp4

This is the new hardware I've patched into my existing computer. On the left is the page table RAM and a NAND IC; on the right is a modified write-only debug port being used as a PID register.

MPEG-4 Video - 39.58 MB - 10/01/2020 at 01:20

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prototype0b-output.mp4

Video output from Prototype 0b. Two processes are running alongside the supervisor, with preemptive multitasking driven by wiring the 50Hz vsync signal into the CPU's NMI pin.

RAM is split into eight pages; each process gets one for its stack and other storage, plus one of the four pages that cover video memory. The supervisor also had a page for its general storage and a page of video memory.

The processes are each printing their register contents. They increment X continually while running.

The supervisor is displaying the total number of times it has run the scheduler.

MPEG-4 Video - 30.02 MB - 10/01/2020 at 01:19

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blockdiagram-prototype0-2.png

Block diagram of Prototype 0 - extending the original architecture with paged memory and multiprocessing, but not protection yet

Portable Network Graphics (PNG) - 79.89 kB - 09/27/2020 at 15:26

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blockdiagram-originalcomputer2.png

Block diagram of the original computer that I'm using as a base to extend and add protected memory

Portable Network Graphics (PNG) - 47.96 kB - 09/27/2020 at 15:23

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