Easy.
Minecraft to the 80s, to completely send the wrong idea of what most future games would be like AND avoid paradoxes by the fact that it has hardly any "spoileriffic" real world things in it.
And an OLPC XO-1 (aka the $100 one-per-child laptop), with linux installed, a USB hub with serial-port dongles, a big manual on programming and a book of tips on how to beat depression (with a hand scrawled note to whit "just wait til the 60s, no-one will be bothered about homosexuality any more; and if you make it to the late 90s, devices with this kind of power will be considered toys") to Bletchley Park just as they were kicking off on the whole Enigma-decoding thing, and watch just what happens as we end up translating pretty much all the third reich comms in near-real time (even that little thing has the juice to do that kind of decrypting, and the money saved on power (either by plugging it into the already-standardised 240v supply, or using the winder-handle during cuts) can go into building direct radio interfaces, cool valvepunk peripherals and other war-effort things) and Alan Turing is granted the opportunity to really flex his muscles. Though, of course, I'd have to make them sign strict, pain-of-death contracts to never attempt to reverse engineer it or reveal what they've seen/the truth of the situation, and to chuck it all in a furnace at the end of hostilities.
Of course, that may well have happened, and the sheer mental leap of learning structured programming from a 1940s perspective and the difficulty of engineering things to work within RS232 signalling protocols (even at 75bps) may be why progress was actually a bit slow.
Alternatively: the catalytic converter to the early 50s, and some other more flashy thing to prove my future-person credentials (maybe an iPad), and issue a few dire warnings about not implementing it on all vehicles immediately, going too crazy with displacement vs cleverness, and to not put lead in fuel you freaking idiots.
Minecraft to the 80s, to completely send the wrong idea of what most future games would be like AND avoid paradoxes by the fact that it has hardly any "spoileriffic" real world things in it.
And an OLPC XO-1 (aka the $100 one-per-child laptop), with linux installed, a USB hub with serial-port dongles, a big manual on programming and a book of tips on how to beat depression (with a hand scrawled note to whit "just wait til the 60s, no-one will be bothered about homosexuality any more; and if you make it to the late 90s, devices with this kind of power will be considered toys") to Bletchley Park just as they were kicking off on the whole Enigma-decoding thing, and watch just what happens as we end up translating pretty much all the third reich comms in near-real time (even that little thing has the juice to do that kind of decrypting, and the money saved on power (either by plugging it into the already-standardised 240v supply, or using the winder-handle during cuts) can go into building direct radio interfaces, cool valvepunk peripherals and other war-effort things) and Alan Turing is granted the opportunity to really flex his muscles. Though, of course, I'd have to make them sign strict, pain-of-death contracts to never attempt to reverse engineer it or reveal what they've seen/the truth of the situation, and to chuck it all in a furnace at the end of hostilities.
Of course, that may well have happened, and the sheer mental leap of learning structured programming from a 1940s perspective and the difficulty of engineering things to work within RS232 signalling protocols (even at 75bps) may be why progress was actually a bit slow.
Alternatively: the catalytic converter to the early 50s, and some other more flashy thing to prove my future-person credentials (maybe an iPad), and issue a few dire warnings about not implementing it on all vehicles immediately, going too crazy with displacement vs cleverness, and to not put lead in fuel you freaking idiots.
