The hard way to recover the IBM 5100 Non-executable ROS

https://github.com/stepleton/5100NonExecutableROSDecode/blob/master/WRITEUP.md

by classichasclass • 7 years ago

76 15 7 years ago

github.com

DanBC• 7 years ago

I love this write up.

There is some information about the 5100, with lots of photos, here: https://www.oldcomputr.com/ibm-5100-1975/

jamesmp98• 7 years ago

I love vintage computing and have wanted a 5100 for a few years now. Unfortunately the only time I've ever seen one on sale was about a year or two ago and I just couldn't afford it

bobblywobbles• 7 years ago

You are much smarter than I, reading this article is evidence of that.

dev_tty01• 7 years ago

Great write up. I loved the computation time estimates based on the target hardware. I have designed a number of CMOS chips during the last 20 years and I have always been amused that the 4 month fabrication time is quicker than the time required to do full chip simulations, assuming they were even possible. I like to refer to chip prototypes as custom real-time simulators.

vectorEQ• 7 years ago

this write up gave me a headache just thinking about this task :D wow what a battle to dump some bytes! excellent and interesting write up for sure! props!

Darkphibre• 7 years ago

That was an excellent read!

I'd be curious if he could have leveraged the CRC check as part of the verification loop.

jandrese4• 7 years ago

Seems like he made a lot more work for himself by trying to save a bit of space on the original capture and doing it at low resolution and with an unsynchronized v-blank.

I did something similar to this many years ago from a screen recording using a copy of gocr and netPBM. Cutting out blocks of text using netPBM tools and feeding them into gocr ended up working out quite well and didn't take enormous amount of cpu training some ML model.

rightbyte2• 7 years ago

I don't get it. Did he do it this way for the fun of it? Surely the computer has to be able to read and then write the rom to other output than the display.

jandrese4• 7 years ago

I think he was nervous about touching any of the hardware in the machine.

ncmncm• 7 years ago

I think masochism has to figure strongly here.

Otherwise he would have re-shot at higher resolution and more frames per screenful. Or something. One goal was to get the bytes out, but the other goal was to achieve it the hard way, and maybe learn some ML on the way.

Dylan16807• 7 years ago

At least reshot, even better write a small program to output each page in base 2/4 (with characters chosen for very easy distinguishing) plus a checksum.

CyberFonic• 7 years ago

I have to admire the effort and persistence that went into this exercise. I certainly enjoyed reading the post from beginning to end.

But ... if it had been me, I would have used a terminal emulator running on a PC and captured the screens in digital format. Of course, terminal emulators can be finicky to set up, etc. But I would hazard to guess that still far less work than the ML approach.

jandrese4• 7 years ago

Keep in mind this is a laptop from 1975. Well, a luggable all-in-one from 1975. I/O options were pretty limited.

The hard way to recover the IBM 5100 Non-executable ROS

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