On Sat, 14 Jun 2003 21:13:55 +1000
"peter tremewen" <ptremewe_at_bigpond.net.au> wrote:
> How much do people think is too much restoration??? >Now obviously you aren't going to spent thousands on a system that even
>in the distant future will not even generate hundreds, and obviously >you aren't going to rebuild and replace every part in the item, because >then it's a replica not an antique.
Really? I have an H740 power supply sitting inside the chassis of a PDP-11/05 that wants to argue with you. As it is, half the +5V regulator has been removed, and is going to have to be replaced. It's not going to cost that much, but still, I fie you to call that a "replica". The important part isn't "Oooh! Shiny old collectible!", it's "watch me make the binkenlights do foo after I toggle this program in on the front panel." There's a PDP-11/45 that my friend and mentor essentially rebuilt. New power supply, grafted-on LTC, etc. Yeah, you can argue that replacing a power subsystem is somehow devaluing the system in some way. The system will be worthless, though, if you use a period power supply. When linear supplies fail, they can do interesting things, like toast your logic. What is the point of having a pristine, unmolested logic board of burnt-out chips?
A different friend of mine recently acquired a PDP-10. The KL-10 sucks down 10KW, 2 for the CPU, 8 for the power supplies. I submit that his modifying the beast to run off of just over 2KW, with switching power supplies, is in no way degrading the worth of the machine. The same with his using modern memory to replace the damaged-beyond-repair memory cabinets. A PDP-10 is a rare enough beast that anything necessary to get it running, including hooking it up to life support, is a fair modification.
Falseness or legerdemain, however, is idiotic. Buying the shell of a PDP-11 and throwing a PC in running simh and an interface layer in is pointless. Or repairing a PDP-8 by reimplementing everything in FPGAs. At that point, it ceases to be the original machine anymore.
Every DEC machine prior to the Middle VAXen came with its own print set. I hold that the power supply is expendable. It's probably dangerous to the rest of the machine, and should be disposed of. Earlier machines *tend* to have simpler power systems (I have a pair of VAX 6000s should anyone want to argue the point), so it isn't completely infeasible to build your own power supply. The more important part is the processor. Except in extreme circumstances, I don't believe you should modify the processor. If the print sets no longer describe the processor logic, then you've created a new implementation of whatever the hell it was that you had. It then ceases to be the old machine, and is some sort of weird hybrid. You're pretty much on your own then if something goes wrong.
-Jesse
Received on Sat Jun 14 2003 - 23:15:00 BST