Slashdot Mirror
Don't Nurse Old Hardware - Emulate It
gManZboy writes "Bob Supnik, former team lead for DEC's VAX microprossesor, has an article up on Queue about his Computer History Simulation Project and how emulating old servers may be a better way to keep them running that servicing the physical machines. So how many PDP-11's can you run on a Pentium 4 anyhow?"
to add to the parent, companies like Intermedia will convert/image your disks for you.
Funny? That should be modded 'informative.' I've never been hospitalized, but I did wind up with a wrist brace for a week or two thanks to some RA-92 hard drives.
Seriously, if anyone wants a free VAX 6000-510, let me know. I need the garage space back. I'm on the central coast of California. I'll even throw in a MicroVAX II or two if you want. They make good end tables.
the PDP-8/e Simulator for Macintosh is a LOADED system (up to 32K words of memory, KE8-E Extended Arithmetic Element, ASR 33 Console Teletype, ASR 33 Auxiliary Teletype, PC8-E High Speed Paper Tape Reader and Punch, RK8-E Disk Cartridge System, LP8-E Line Printer, and a KC8-EA Programmer's Console) that runs a quite a bit faster than the original - fastest benchmark is a G4/450 at about 22x; my 2x1.25 runs the tests well under 1sec. If you need to support an -8 legacy, this seems like the logical way to go.
Facts do not cease to exist because they are ignored. - Aldous Huxley
Any half-decent emulator will pay attention to cycle counts. It's one of the few things that distinguishes an emulator from a virtual machine. Take MAME for example - all the CPU emulation in there tracks cycles.
The way it basically works is that process is started, and an approximation of entire image is copied over to the other machine. After a minute or so on some images, more on machines with many resources, the machines are basically close in contents. When the delta between the machines is fairly small, execution on the first is stopped, and all changes comitted to the second. Commands in the pipeline are moved to the second machine and the machine unpaused.
On virtual machines with big resources it does take a solid minute or more to get things to that point, but the result is flawless everytime. Having a shared fast disk array really helps, FYI.