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2025

  • 1 min read

How to speed up Linux

Disclaimer: only do this if you don't care about heartbleed, zombieload or spectre exploits (aka, don't do this at work or in the cloud or on a shared hosting service - only on your own VMs at home or somewhere where bad guys won't be visiting)

Append the kernel parameter "mitigations=off" to your boot line.

The "mitigations" are patches to the linux kernel to protect any data leakage in a hypervisor situation where you are running a VM and a bag guy is also running a VM on the same host. There are hacks that use exploits to break the barrier between the two VMs and it can cause some data leakage. These mitigations cause the CPU to be substantially slower however, so removing these mitigations helps speed up your computer overall! So, this simple change gets you between 30% and 80% faster machine!

You're welcome.

  • 2 min read

So I bought a broken, old school pen plotter

I have a drafting degree. I also did some art stuff when I was in-between the Navy and my college experience. When I found a cheap-o pen plotter on a local government auction site for $14, I couldn't say no.

What I received:

![[plotter.jpg]]

Lots of unwrap here. The bottom legs are missing two wheels. It's not an HP, it's a Mutoh (model XP-501) and it has some paper jammed into the printing area.

Time to find out as much as I possible can about it. After about 2 days of googling, I found out that it's a pretty popular printer and it supports HPGL (the plotter 'language' that most pen plotters use), so that's good. I went ahead and bidded on it and won.

Pros: it came with like 10 sets of pens, all new in their wrapper. It powers on and jiggles the pen holder and when I put paper into the plotter, it zipped the paper back and forth (measuring it, I'm guessing). It's alive!

Cons: It didn't come with a pen holder (carousel). This (it turns out) is almost a complete deal-breaker. I email'd the auction owner and he said that it comes as-is, but he'll keep his eyes out for the carousel.

Closer analysis found that the carousel "pit" has a bunch of sensors in it. One at the bottom to detect if the carousel is inserted. One on the side to detect which pens are present, and 4 more on the side to read bar codes of potential "pencils" and what their capabilities are. The print can accept these pencils (I didn't know that plotter pencils were even a thing) and they have stripes on the pencils to indicate the lead width and other things.

So, when I powered the plotter on initially, an error appeared on the screen: "ERROR: Stocker missing". I stuck a screwdriver down in the pit and after finding the bottom sensor location, I was able to get the bottom pan carousel drive motor to start spinning.

I found a guy on the internet with a working plotter (probably the only one)