FPGAs, unobtanium and FPJ11s
pete at dunnington.plus.com
Sat Nov 25 06:43:02 CST 2006
Roger Ivie wrote:
> On Fri, 24 Nov 2006, Richard wrote:
>> Would it be possible to do the same sort of trick with the LSI-11?
>> I've got an 11/03 and it would be nice to have floating-point :-).
> There were a couple of floating point options for 11/03. I haven't
> actually seen either.
> The first, FIS-11, was a ROM that goes into the empty socket.
> The second, FPP-11, was an add-on board that connected to the 11/03 via
> the empty socket.
I think you're confusing this with 11/23, or maybe 11/40 options. There
is a microcode ROM for the 11/03, which contains EIS/FIS (ie, both the
Extended Instruction Set and the Floating Instruction Set). It's called
KEV11, not FIS-11. There is a FIS option (and a separate EIS option)
for an 11/40. However, the FIS is not the same as other PDP-11 floating
point instructions. For a start, it's all stack-based (no register
operations) and it uses a different floating point format. Which is why
the opcodes are different too.
There's a similarly-named option called KEF11 for an 11/23, which does
implement the normal PDP-11 floating point instructions (in microcode).
It needs the MMU present, because it uses registers in the MMU; it
doesn't implement EIS because the basic 11/23 KDF-11 chipset already has
EIS, unlike the KD-11 chipset in the 11/03. It doesn't implement FIS
either, because there's no point. There is also a quad board with a
floating point processor which plugs into an 11/23 (or 11/24) instead of
the KEF-11; this is called an FPF-11, and it doesn't need the MMU
registers because it has its own.
I've never heard of an FPP-11. There are several FP11-x boards for
> As I understand it, the empty socket could be used for either floating
> point or the commercial instruction set. Since there's only one empty
> socket, you can't have both floating point and the CIS.
There's no CIS for an 11/03; there is a CIS option for KDF-11 machines,
which consists of a carrier that plugs into a *pair* of microm sockets
on an 11/23 or 11/24. The carrier holds six chips. There's also a CIS
for the 11/44 (two board set).
> There's also a writable control store, WCS-11, that plugs into that
Yes, that's a KUV-11, M8018. I suppose if you could fit the floating
point instruction set into 1024 microcode words, you'd almost be able to
implement floating point -- but there would still be no registers
available to operate on.
Pete Peter Turnbull
University of York
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