The Cuneiform Tablets of 2015 [pdf]
vpri.org
vpri.org
Also many old films have been lost for similar reasons.
The python PEP for universal linux binaries advises building on an ancient version of fedora for ABI compatibility.
If you think about it, supporting many different deployment targets is kind of like time travel.
And yet The Centre for Computing History in Cambridge has its exhibits powered up - including a collection of several Domesday Machines.
But a negative or a positive image? Not a problem. Never gonna be unreadable. There's a time and place for both formats, just like there is a time and a place for both a Kindle book and a real paper book, and it's important that we make a point of thinking carefully about which the circumstances dictate: convenience or long-term survival.
But seriously, how many photos does anyone bother to preserve on archival quality materials? I've lost family photos due to fading, floods, and simply losing them. I've digitized most of the remainder, in order to preserve them.
I have digital copies, of course, too, and those are stored on my iMac, in a backup hard drive, in Backblaze, and on S3.
Some weirdo RAW format? Will probably suck to deal with. Already sucks to deal with. Don’t expect it to last long and maybe keep the JPGs around for your grandkids or rather grand-grand-grand-grandkids.
JPG? I’m quite willing to bet that, baring the apocalypse, this format will be easy to read in 100, 500 or 1000 years. I’m really that certain about it. I’m even certain that in 100 or 500 years whatever OS on whatever device will come with out of the box support for JPGs. Maybe you will need an afternoon of digging to get JPGs displayed in 1000 years … but that should be about it.
Ok, ok, those predictions are quite absurd, but I really would be wary of underestimating the existing and continuing ubiquity of the JPG format. There are probably billions of JPGs created every day, even if you limit it just to JPGs that result from light hitting some sort of image sensor. And that will continue for at least a couple decades. In the end a, what, maybe 80 to 100 year active lifetime of the format (remember, we are already at a quarter century) might seem short in the grand scheme of things, but the cost of just keeping support around will be so low … (again, barring the apocalypse)
My OS can open some weird-ass image formats right out of the box. I can None of those formats (no other image format, period) has ever been as popular or as widespread as JPG … by a wide, wide margin. JPG is gonna be ok. If nothing else.
So I wouldn’t worry about the format. I would worry about what you use to store those images and how you will hand it down. (Often analog photos are on some attic or similar place somewhere, often long forgotten even by the person who took them. Then someone stumbles across them and that is beautiful. Not so easy to recreate with digital images. How do you stumble across that? How do you just keep it around somewhere safely)
You are certainly right that film negatives or positives are more likely to survive the literal apocalypse (where we lose all knowledge about using computers), but I’m not so sure about them being more likely to survive into the deep future … (Though in some ways you do have a point: I think in some ways it’s more likely that your grandkids will stumble across and know how to deal with your box of negatives in the attic than, I don’t know, your old hard drive? Your old PC? How do you even keep such stuff around?)
But my point is this: JPGs are easy. Move beyond that and it gets hard. Any kind of interactive content is a nightmare.
/* PPM P6 file format; see <http://netpbm.sourceforge.net/doc/ppm.html> */
static void
output_header(int ww, int hh)
{ printf("P6\n%d %d\n255\n", ww, hh); }
static unsigned char
byte(double dd) { return dd > 1 ? 255 : dd < 0 ? 0 : dd * 255 + 0.5; }
static void
encode_color(color co)
{ putchar(byte(co.x)); putchar(byte(co.y)); putchar(byte(co.z)); }
This is pretty dishonest. Images fade; that's not a different problem from formats being lost, except to the extent that an image in a hard-to-read format might still be recoverable. For example, tiff is uncompressed pixel color values; you could recover that easily without having a tiff reader or even knowing what tiff was.
Also, I'll note that the comment I responded to specifically claimed that positive images last forever.
The big difference between analog and digital is that with analog, you can simply stuff it in a box and it will stay there. With digital, you have to take the time every now and then to make sure that you don't lose that stuff. And do you really think that you (or someone else, when you are gone) will be doing that properly? I mean, you will most likely have forgotten why that stuff was even "important" in a few years.
There's so much great stuff our generation is going to lose, simply because we'll forget to migrate our backups.
"You may remember collecting data for the 'National Disc' which, unfortunately, we have not been able to re-publish at this time."
Raw text itself is pretty compressible, but pdfs record everything about the layout and typesetting, font choice, small smudges on the page, etc. You could maybe run OCR on them and get the text (if the OCR is reliable enough.) But then you lose equations, figures, unusual symbols, and other important info.
I've been thinking a lot about how to solve this problem myself.
Kay says their Smalltalk virtual machine for the 8086 was 6 kilobytes of machine code; I think we can do several times better than that. The most recent BF interpreter I wrote, in 2014, http://canonical.org/~kragen/sw/aspmisc/brainfuck.c, is a bit over a page of code, and with -Os, it compiles to 863 bytes of i386 code (768 bytes .text, 38 bytes .init, 23 bytes .fini, 34 bytes .rodata). Maybe the ideal archival architecture would take a little more code than BF to interpret, because an actually efficient BF implementation has to do all kinds of somewhat unpredictable optimizations.
Some kind of Forth machine, like Calculus Vaporis https://github.com/kragen/calculusvaporis, is one possibility.
Another would be a simple register machine, something like the PIC; also in 2014, I wrote a proposal for a nearly-MOV-machine version called "dontmove" at http://canonical.org/~kragen/sw/aspmisc/dontmove.md. The C implementation at http://canonical.org/~kragen/sw/aspmisc/dontmove.c compiles to 855 bytes of i386 machine code (38 .init, 784 .text, 23 .fini, 10 .rodata) and is dramatically more efficient than a simple BF implementation, and unlike BF, it has features like memory indexing and subroutine calls; but it's not as well tested.
Each of BF and Dontmove took me about half an hour to implement. Even though a simple Dontmove implementation is exponentially faster than a simple BF implementation, it's still orders of magnitude slower than native code. I'm still exploring how to better bridge that gap; ideally implementing the virtual machine wouldn't take the entire afternoon that is the goal of Chifir, and it wouldn't run as slow as Chifir. I suspect that some kind of SIMT architecture (like GLSL and GPUs in general) might be the right path, allowing a simple emulator to amortize interpretation overhead over many lanes of data. I expect Alan would be allergic to this idea.
As mentioned in the Cuneiform paper, Lorie and van der Hoeven have published some papers on what they call a Universal Virtual Computer, directed at archival, but unfortunately some of the design decisions in the UVC run strongly counter to the goal of ensuring that from-scratch implementations have a good chance of being compatible: bignum registers, for example, and complicated fundamental operations like float division. The consequence is that writing emulators to run on the UVC should be very easy, but no two implementations of the UVC will be compatible, so those emulators will not run successfully on new implementations of the UVC written after we are all dead.
An issue barely mentioned in this paper is I/O devices. You'll note, for example, that Chifir has no mouse and no real-time clock, although it does have a keyboard and a framebuffer; its keyboard interface is somewhat underspecified but appears to lack control, alt, or other similar modifier keys, and there are no key-release events, and as abecedarius points out, reading the keyboard is blocking. This means that it will be impossible to write simple video games for Chifir that move your guy only as long as you hold down a key, and the lack of a real-time clock means that it can't do animations at a constant speed. It's likely that the specification and implementation of I/O devices for an archival virtual machine will require as much effort as that of the CPU.