FPGAs, unobtanium and FPJ11s
bqt at softjar.se
Fri Nov 24 08:24:19 CST 2006
Gordon JC Pearce <gordon at gjcp.net> skrev:
> The thought occurred to me that it might be nice to have the
> floating-point option in my PDP-11/73. Since I haven't got one, and
> don't fancy paying the $500 or so that some online sellers seem to be
> asking (do they really expect to sell *any*, never mind at that price?),
> I was wondering how easy it would be to implement in an FPGA as was
> discussed at length earlier in the week.
> Feasible, or a complete waste of time? Presumably I'd need software
> written to make use of the floating-point hardware anyway...
Can't really answer your primary question, but to fill in some
information for you, the FPA for the J11 is an *accelerator* (hence FPA,
and not FPP). It will not add any instructions to the CPU. The J11
already implements all the instructions of the FP11. What the FPA do is
speed them up.
And software wise, there is plenty of software that uses the FP11
instructions. Mostly high level languages, though.
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