here is a 7 digit vacuum fluorecsent display model made in
japan. it has the
basic 4 functions, a memory and percent plus handy reciprocal and square
function buttons and is one of the custom green line family.
this model has 2 removable AA batteries. i find this much preferable to
the built-in battery packs of other models like the 9r31
and the sr4148r since, over the years, the
batteries corrode inside the machine, leak and destroy the electronics.
many commodore models (like the 776m) operated
a one key memory. the `m' key is used both for recall and store. if
pressed after =, it stores the current value into the memory,
otherwise it recalls the memory contents into the calculation (eg 1+2=M,
the ex button swaps the two values of an operator eg. 7/4^2 is 4
x^2 / 7 ex = (note that 7/4 x^2 gives instead (7/4)^2.
it appears to use 8 digits internally, but wont round back 1/3*3 to 1.