[solarexplorer]

Register windows are a way to put 1000 registers in a CPU. See the SPARC and Itanium instruction sets for how this can be done. There are also plenty of studies about both.

Vector registers are another way to use 1000 registers.

But directly coding 1000 registers into each instruction does not seem to be such a good idea. You might as well use a 1st level cache. The difference between the cache and the register file ist mostly how the instruction set architecture references it. Registers are usually easier to acces because each one has a single name and the CPU can detect dependencies and conflicts easily. Memory accesses and caches are more complex because you need to calculate the addresses before you can detect dependencies/conflicts.

PD: Yet another way to use 1000 registers is massive multi-threading like the Tera MTA.