casio as-8a

a rather cool and natty mains desktop model from around 1971.

the 8a (with 8 digits) is more modern than the as-l  having a vacuum fluorescent display rather than nixie tubes, although the display digits are separate units.

the digits are bright and elegantly styled, especially the number 4 which has a small extra segment at the right tip of the horizontal bar and the small zero, which was usual at this time and appeared in pocket models like the pocket mini and some early scientific models (eg  fx-10 & fx-20). the display might have been influenced by the successful sharp qt-8d.

it operates like a normal desk calculator with the usual separate += and -= buttons. a switch activates an optional constant and another switch can select 0-4 decimal places or full 8 digits. unfortunately the digit truncation does not round so, for example, 2/3 (with 2 decimal places selected) shows o.66 

the machine will overflow if more than 8 digits are entered, showing E on the left.

inside you can see the display units are separate vacuum fluorescent tubes with a ninth tube for the sign.

here we see also, a much more simplified circuit with a single chip cpu rather than the older 4 chip models like the as-l and sharp qt-8a. one downside is that, although being a later model, it is actually slower than those older ones. for example the sharp micro compet (qt-8a) performs division with no noticeable delay, but this model slowly ripples the answer through the digits. presumably this was down to having to achieve all functionality on a single chip.


the keyboard is rather nice because it operates by magnetic reed switch proximity, just like the earlier as-l. the machine is slightly smaller than its predecessors and it is nice to have this kind of gorilla proof keyboard which virtually never wears out and is very reliable.