Card Readers

bhn is nothing but brinelll hardness test in which only cast iron and non ferrous material like brass,gun metal,copper etc are test by the use of ball indentor on 136 mm dia leaving a indent on the tester material of abt 0.8 to 0.9 mm dia measured by micrometer of lc 000.1 whereas in bh its tested on the vickers basis which has a ball and diamond indentor of around 10 mm dia and leavings a rombus impression whose the side r arouned 0.4 mm in length and the diagonals rate for around 0.8 mm which is measured by vickers scale of bh tester... moreover there is contionous deformation in bh test for non ferrous materials which prones to the deaccurate value of the toughness of the material.....

i hope this answer leads u to the satisfaction up to some extent... if anymore queries please feell free to ask

thanks

c ya

Wrong thread, good answer though

The last card reader I've heard of was a Hewlett-Packard calculator used on the space shuttle. It used paper strips to input complex programs. Some of the rich kids in school in the late 70's (I Think?)had them.

Time cards may be another lead.