Seems there's a buncha business software from Back In The Day, that runs on those quaint old minicomputers: PDP-11, VAX, HP-3000, and so on.
(HP-3000? Which generation? I seem to recall there was a total architecture change in the 80s. The one I hacked on in high school was a stack machine, and I think the newer ones are RISC or something...?)
Anyway: someone's gone and written emulators and is offering use of them as a cloud service.
Many years ago, I had the notion of implementing a PDP-11 CPU as a VHDL learning project. I subsequently switched to learning Verilog instead, did a few FPGA projects... and still haven't done that PDP-11, let alone the DEC-10 that's also on the "somebody oughtta do this" list.
Seriously, though: a fairly cheap FPGA these days should be capable of handling any of the old 16-bit architectures, much faster than the original hardware. Add an SDRAM chip and a microSD socket, and you've got a complete PDP-11, Nova, Eclipse, HP-3000, TI-990, etc., all in a business-card-sized form factor. If you want to run a timesharing service on it, you'll need a much bigger board to handle all the connectors. And, of course, a 9-track controller/formatter can be shoehorned into the same FPGA, but the connector for the drive (never mind the drive itself) will dwarf your actual computer.
And then there's the problem of getting ahold of the antique operating system of a long-defunct company... and permission to use and/or distribute it.
Still, it's a cool possibility. Maybe, In My Copious Free Time, I should design the hardware and create a couple of example legacy CPUs, plus the supporting cores for a typical application or two (e.g., making an SD card look like an array of DG disk drives). Probably needs a (yuck) ball-grid package and many-layer board, just because FPGAs with lots of logic don't tend to be offered in QFPs. So, keep the expensive board as compact as possible, and have fine-pitch stacking headers for a cheap, 2-layer I/O board?
And that way you could own your legacy solution, and have a bunch of spares in a shoebox in the office supply closet!
(Now I'm thinking back to the MicroVAX a former employer rented from one of the other employees, and the way it'd load its microcode from a little tape cartridge. Cute! But now the tape cartridge would be a little flash chip, and the process would take hundreds of milliseconds instead of a few minutes.)
Update: Foo. Don't have a handy source for 18- or 36-bit-wide DDR SDRAM. There's a 16Mx18 RLDRAM part, which I guess would do the job, but the supply appears to be drying up. Oh, well. If I really thought there was a market for the dingus, I guess I could call around to memory vendors.
Update 2: The heirs of Sir Henry Ninebit-Byte will be relieved to learn that Cypress Semiconductor is still making synchronous SRAM chips in 9, 18, and 36 bit widths, with capacities up to several Mobies on a single chip. A 4-Moby part runs about $50 in onesies; not bad. And... these things are fast enough that an 18-bit, or even 9-bit, memory bus would probably outrun the CPU (and would most assuredly outrun one of the originals).
Man... I remember the days of 1024-bit RAM chips. With microsecond cycle times.