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Will KEF-11A FPP from KDF-11A (11/23) work in KDF-11BA (11/23+)?

retrobits

Experienced Member
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May 22, 2007
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Location
Portland, Oregon, USA
(also posted on CCTECH)

Hi there,

I have a floating point processor (FPP) on a currently unused 11/23 CPU M8186 card (KDF-11A). From the manual, looks like this is a KEF11-A.

Also, in my working 11/23+ with KDF-11BA, I have no FPP. Makes it hard to use Fortran-77. The KDF-11BA manual refers to a KEF-11AA FPP.

Does anyone know if the FPP unit is compatible from the 11/23 to the 11/23+ - i.e., can I transplant the FPP chip from the 11/23 to the 11/23+ CPU card? Could it be that simple? :)

Please be gentle if this is a stupid question. I've used my best Google-fu and RTFMing to find the answer (and learned some new things about these cards in the process).

Thanks!

- Earl
 
I'll take a crack at this... if your M8186 where the chip is coming from is 22-bit capable, then I think the 11/23+ (QUAD wide bd, right?) will accept it. I'm not dead familiar with issues of the FPP to be certain of other combinations. I don't recall any specific problems though.

You may want to check for a module jumper, but I don't recall it even requiring that. It'll probably be that simple.

And yes... Floating point is pretty much required for DEC F77. (and Fortran IV too)
 
Option chips used on the 11/23 and 11/23+ are interchangeable

So, the same FPU, MMU, and CIS chips that work on the dual-wide 11/23
will most definitely work on the quad-wide 11/23+

You should also be able to use an FPF-11 (the separate floating point board) on the 11/23+
 
You should also be able to use an FPF-11 (the separate floating point board) on the 11/23+

Hey Tim, did you ever get around to trying one of those eBay FPF-11 boards with one of your 11/23? I was tempted to buy one of those when several were listed a while back but never did.
 
Option chips used on the 11/23 and 11/23+ are interchangeable

So, the same FPU, MMU, and CIS chips that work on the dual-wide 11/23
will most definitely work on the quad-wide 11/23+

You should also be able to use an FPF-11 (the separate floating point board) on the 11/23+

Thanks for the responses. You'll be happy to know it worked perfectly. I am now floating point capable, and can F77 with the best of them :)

Cheers,

- Earl
 
Hey Tim, did you ever get around to trying one of those eBay FPF-11 boards with one of your 11/23? I was tempted to buy one of those when several were listed a while back but never did.


No -- I haven't been poking around with the PDP-11 lately; I rarely see them on e-bay,
so I thought I'd grab one while I had the chance, in case the right mood hits me. ;-)
 
No -- I haven't been poking around with the PDP-11 lately; I rarely see them on e-bay,
so I thought I'd grab one while I had the chance, in case the right mood hits me. ;-)

There is one there now, but asking a lot more than when several were sold a while back.

http://www.ebay.com/itm/291248748372

That one wouldn't make much sense when you can usually buy an 11/73 CPU with FPU for less than that.
 
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