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by canucker2016 127 days ago
Not the original poster, but when I was re-watching the series I also checked the reddit postings for each episode I watched. One of the comments for the first episode mentioned how laborious they made the act of dumping the IBM PC BIOS contents.

So in the first episode, Gordon Clark, the HW guy (played by Scoot McNairy) had to dump the contents of the IBM PC BIOS from the ROM chip.

Gordon extracts the BIOS chip (an 8KB EPROM chip if you do a web search) and plugs it into a breadboard and proceeds to dump out each byte of the chip with Joe (Lee Pace) writing down the address and data at that particular address on a pad of paper.

After writing the address and address contents for the first time, Joe asks Gordon how many times they have to do this procedure. Gordon replies 65536, which would imply a 64KB ROM chip - but the web search said the IBM PC used an 8KB EPROM for the BIOS.

After more dreary, repetitive work, they accomplish the dumping and transcribing of the IBM PC BIOS in one weekend.

But one could have used a short BASIC program to dump the IBM PC BIOS ROM - the IBM PC wasn't a locked down game console...

Maybe as a HW guy, writing a BASIC program to dump the BIOS would not come to mind.

For a legal clean-room implementation of the IBM PC BIOS, the actual contents of the IBM PC BIOS aren't needed.

You need the specs for each BIOS function (input/output parameters and description of what the BIOS function does).

The IBM PC Technical Reference Manual (which cost $99 back then) contains the BIOS assembly language listing.

One would need to type up the lines that list the input/output requirements for each BIOS function and their purpose and they'd be half-way to a clean-room PC BIOS.

But that'd be way less dramatic (and easier) than the way shown in the episode.

see https://electronics.stackexchange.com/questions/112846/halt-...

2 comments

Excellent example. I do actually remember that part as being particularly cringeworthy. The IBM PC Technical Reference Manual also included complete schematics for the motherboard as well.

And, as an added bonus, as a hardware guy would know that you could read back the contents of an EPROM using the software that controls your EPROM burner (not an expensive piece of equipment). So that excuse doesn't fly either.

I don't really understand the first episode. The idea as far as I can tell is that it's illegal to use employees who reverse engineered the BIOS to clone the BIOS, but it's legal to hire someone new, who presumably is also going to have to reverse engineer the BIOS in order to clone it.
The idea is that specifications are not copyrightable, but implementations are. So, the first team reverse engineers the work and writes a spec for the second team to work from. That way, you guarantee that the second implementation is free of copyrighted code.

https://en.wikipedia.org/wiki/Clean-room_design