PMC-20 updates

A few notes on my mini computer.

I re-wrote MPE (the user shell/commands/accounting system) on and off over the last few months. MPE is now version 3.02. I’ve added a lot of user programs and added features to the utilities I already completed.

I’m finishing up a line editor that’s somewhere between ED for the pdp-8 and TECO. All the user utils  (cd, copy, attach, type etc) are multi-user safe and as optimized as I can make them.

I found out about the Linux kernel  atime bug that breaks some of my system monitor stuff. Too bad the kernel devs want to keep it broken. Oh, well.

I made a file system change that made a 200% speed up to the user experience. Very happy with that.

I wrote a couple drivers for low speed and high speed paper tape readers.

I wrote a tape drive driver. I can’t find my 500 mb tape drive so I emulated one using sequential files on various media. Really happy with it - I can type “tape save” and save versions of software in seconds. Lots faster than reel to reel drives.

I rediscovered cobol. Wrote the user accounting package in it. Called money, just like DEC’s version. Looks better. Runs faster. Output looks good on my line printer.

All the things I wanted to do in college but didn’t have time or ability. I do now.

Uptime is now 276 days without a hiccup. I need to move it to another room, but don’t want to just yet.

~ Kurt

Update 1/24/18

So, I wanted a way to transfer files, programs etc between devices and people. So I wrote a new file system called MPFS, MPE Portable File System. It’s a fat type system with 65536 512 byte blocks and 256 directory entries. Total size is around 33MB. I want it small because most of what it will be storing are source code, small executables etc. Most of the system executables for MPE are about 20k to 30k. They are dynamically linked so they stay small.

I’m writing the driver to use MPFS into MPS so that access will be transparent and fast.

The next step in put everything in protected memory at boot up (the heap and a small stack) and run it out of memory.

~kurt

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