FYI: I am in CA and my startup is in no way related to what I work on at my day job.
For elaboration, here's your risk/reward calculation. Reward: you save N days worth of your present salary which you should spend on a cheapo laptop. Risk: you are planting an unrecoverable flaw deep in the heart of your company. It only matters if your startup does well, but if it does, it suddenly matters a lot. If you are in talks for an acquisition or funding round five years from now and this topic comes up in due diligence, your company is over. It does not matter whether you'd win the legal case -- and you wouldn't -- because there will not even be a legal case. The risk-averse counterparty you'll then be dealing with will nope-nope-NOPE out of that transaction and do business with someone who is capable of minimal levels of professionalism.
Also, while I hate to be the bearer of bad tidings: given that there is no way to untaint the project you are presently working on, I think you're probably better off rm -rf'ing N weeks of work and starting over rather than taking the somewhat accelerated timeframe on a project which has an unfixable timebomb embedded in it.
If you do a reimplementation it will go much, much faster because you now know what you're doing.
Get a second hand laptop or a Chromebook or something. If you're able to get a job programming you should be able to afford something.
However, there's another obvious risk: if your employer fires you for any reason, they'll demand your laptop back immediately, and you may not get the chance to retrieve anything that's on it (e.g., you may be immediately escorted from the building by security). Anything that's stored on the laptop may fall into your employer's hands at that point.
Also, use of company equipment for personal use may violate your company's own policies, and may give them grounds for firing you. You said you work for a "big corp" - they frequently have rules like that in their employee handbook.
Do yourself a favor and get your own machine to do your personal stuff on.
http://www.brightjourney.com/q/working-company-intellectual-...
The key phrase seems to be this one: "These state legislatures usually passed laws that said something like this: Anything you do on your own time, with your own equipment, that is not related to your employer's line of work is yours, even if the contract you signed says otherwise." (emphasis mine)
This suggests doing external work on company equipment might be a bad idea.
The law basically says that your employer can claim ownership over any work product you make while in their employ (i.e. in the workplace) or using their equipment. So cease immediately if you don't want to potentially forfeit your creation, and use solely your own equipment, outside the usual workplace, to develop it.
In this case a used $100-$300 machine is probably the minimum necessary expenditure [as opposed to a new MacBook Pro or it's equivalent].
Implementing a sound backup strategy is more important than any gain in reliability between new and used hardware.
A builder needs tools. Get your own tools, build your own stuff. Have no worries. Simple as that.
If anything, owning no other machine does beg the question of how you got it all kicked off, doesn't it?
Of course it might be nicer to have your own laptop that is setup just right for what you're building, but if money is scarce then i would just use the work laptop and keep quiet about it.
The cost of a new laptop is fixed and small. The cost of a successful startup being destroyed is potentially massive.
It's totally possible to code Erlang on a low-end netbook.
The cheap laptop I wrote early self-employed code on was under 20% the price of a cheap Mac and so badly made it was flexible.
The work I produced on it paid for the eventual upgrade.
I agree with other commenters saying you should dump your current codebase and reimplement from scratch.
Note: I am not a lawyer.
"Related to" is a very loosely-defined term. Don't be so sure that your startup is not related to your work at your day job.
It wasn't that I couldn't afford it, but its just more convenient to have everything on one computer. Yes, looks dumb now looking back at it...
Seriously computers are cheap go buy one.
if you're doing it for convenience, it ain't worth the jail time.
if you're doing it because your work computer has expensive development software, you're breaking ethics and legal agreements, then you'd deserve the jail time.
if you're doing it for any other reason ,DONT.