# What skill should a Tech-priest use for reprogramming machines?

What skill should one use for tasks that require reprogramming machines or (apparently) designing entirely new software?

Tech-use and Security seem to operate on a mechanical/physical aspect, as all the eventual Trade skill-groups (like Technomat) do. Should I make a new skill like Trade (Programmer)? Or even Trade (Software Designer)? Trade (Software Engineering)? :P

From what I read in the books, Logic could be the right skill for this job, but it's not said explicitly.
EDIT: it's said in the Logic skill that Logic is theory and Tech-Use is practice.

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There doesn't seem to be a definitive book answer for this one. I'm actually inclined to think that this is on purpose, and there's no such skill - all such rolls should be made on Tech-use or an appropriate trade skill.

I don't think you should add Trade (Programmer) or Trade (Software Engineer), because I don't believe those professions actually exist in 40k.

This is to do with universe feel. 40k Imperial and Chaos tech is mystical and badly understood; while there must obviously be software and programs, they don't see much abstract computing. 40k doesn't seem to have any common equivalent to the general-purpose computing device; almost all software is embedded control software, tied to a specific machine. I can't think of any reference in the source material to a programmer who isn't also an engineer.

Indeed, given the focus of the 40k tech-base on reproducing standard pattern devices and then jury-rigging modifications, there may actually not be such a thing as a general-purpose high-level programming language in most of 40k space - that requires a degree of technical understanding that probably only the Tau and Eldar have. Quite possibly each category of devices just has its own embedded programming language, and learning to code in it goes with learning to build and maintain the device.

So I'm inclined to think that rolls to handle programming should be on the appropriate skill for whatever device the PC is trying to modify or reprogram.

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@lunadir: There's no evidence that 40k has a standard network protocol, just a mass of individual protocols used by specific gadgets. Much less an office suite as we understand it. It's generally going to be Tech-use, but the key is: forget that it's software, use whatever skill is appropriate to do it in hardware. "Write addon to office" should be viewed as "use the computer that you're running office on" for skill purposes. There is no generic algorithmic coding, because they've lost the concept of generalised algorithm. – Tynam Jul 6 '13 at 23:47
@lunadir: Sure, there's software involved, but the skill to roll in game should be based on the hardware. 40k people learn programming as part of the handling of specific devices, not as a general abstraction. It's not that they have everything precooked; it's that they don't have .Net or Java, just cruder embedded languages. (This is getting kinda involved; can you explain what needs improving in the answer directly, or should we take this to chat?) – Tynam Jul 7 '13 at 9:27
I'm with @Tynam. Knowing generalized algorithms or any other kind of skill that, outside of game, we would call "computer science" as opposed to "programming," is unknown and therefore heretical. (And therefore good cause for an Inquisitor to give you one in the head from his bolter. That will keep the software engineers I play with from metagaming next time we play Dark Heresy!) – dodgethesteamroller Jul 7 '13 at 21:34
In the WH40K universe, you don't program things - you perform specific rituals to bind machine spirits into the device, or to implore the existing machine spirits to act in different ways. Blood sacrifice might be involved in extreme cases; In that respect, it's no different to today's programming practices. – GMJoe Jul 8 '13 at 6:01
Reprogramming a machine is doable without being heretical, it just depends on how you go about it. For example, the Litany of Data Integrity is used to change the instructions that the holy machine spirit in your cogitator uses to perform your daily backups. In functional terms you are changing a script and reprogramming a part of the system, in world terms you aren't programming but instead going through the sacred motions to change the instructions that are given to the machine spirit. A heretical action would be to rewrite the twenty thousand year old code in the backup daemon. – Colin Jul 11 '13 at 8:18

The adventures seem to use Tech-Use for programming and hacking tasks. Therefore, Tech-Use seems to be the relevant skill.

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It's not much a matter of (this) adventure, it's a matter of fiddling with technology, which happens pretty often in this game (expecially when you're a tech-priest...). | Not only Tech-Use seems to be exclusively hardware-related, but using one skill for everything seems a bit like cheating (and a bit boring). – lunadir Jul 7 '13 at 8:52
Still, the in-print adventures use Tech-Use for programming and database operations. It's the skill the dev team chooses for the answers. – aramis Jul 8 '13 at 8:01
Maybe I will search novels about tech-priests (if only I could decide). – lunadir Jul 8 '13 at 19:12