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This 51-A is original or has been changed?
Blue keys?

SR-51A Rare?

(02-22-2015 02:15 PM)hp41cx Wrote: [ -> ]Blue keys?

A quick look at Jörg's datamath.org site shows that even the non-"A" SR-51s had yellow keys. So it must be a frankencalc with components from an SR-50.

(02-22-2015 06:23 PM)Marcus von Cube Wrote: [ -> ]

(02-22-2015 02:15 PM)hp41cx Wrote: [ -> ]Blue keys?

A quick look at Jörg's datamath.org site shows that even the non-"A" SR-51s had yellow keys. So it must be a frankencalc with components from an SR-50.

I accidentally happen to have those units and yes; that could be. It could also be at the end of the run and assembled from whatever fit. To prove that though; we'd have to check serial numbers. I know National Semiconductor would "make the best of a bad job" with what parts were at hand.

Let's believe in the frankencalk.

(02-23-2015 12:02 AM)Den Belillo (Martinez Ca.) Wrote: [ -> ]Let's believe in the frankencalk.

Simply the wrong functions at the wrong position. No need for believing.

d:-)

(02-23-2015 06:16 AM)walter b Wrote: [ -> ]Simply the wrong functions at the wrong position. No need for believing.

What's wrong?

in addition to the blue keys there are also white and grey keys that differ from the standard 51A:

This is relatively easy to create if one has an SR-50 and an SR-51A. I made one once for fun.

The keys are totally interchangeable as long as the function printed on the top is the same.

Looks fun!