Additional Pictures 


The printed circuit board of the original SR-50A 
design makes use of a TMS0521 SCOM chip. 

Early SR-51A calculators mounted the second SCOM chip in a piggy-back manner on the first one.

In the last production year of the SR-50A it uses the same PCB as the late SR-51A and SR-56 Programmable. 
The new SCOM chip reads

The redesigned SR-51A sports two SCOM chips 
TMS0532 and TMS0533. Please notice the empty
space for the Memory chip of the SR-56.


horizontal rule

If you have additions to the above article please email:

Joerg Woerner, June 7, 2005. No reprints without written permission.