commodore sr-4148r

this model has the luxury of 48 keys and subsequently does not require a shift key (unlike the sr-1800). several commodore models preferred no shift or 2nd key so to have all functions on individual buttons. this made for efficient operation.

the usual scientific functions are all here. there is no operator precedence between + and *, but there is for x^y. eg 1+2*3 = 9 (here) and 1+2^3 = 9. brackets seem to only work to 1 level. accuracy is quite good (using 2 extra digits), although the machine has a noticeable delay calculating. the display is quite good, you get 10+2.

it has two memories 1 & 2, but memory 2 is also used for series tally, using the Xn button. pressing this accumulates the total into m2, also the average value can be found by swapping it with the sum using x<>s.

i quite like the exponent manipulation on the top row. this scales the exponent up and down one at a time, similar to some eng display modes but not in multiples of 3.

a nice touch is the degrees/radians selection via d-r which doubles as a converter. on power up the machine is in degrees. when in radians, a small dot is lit on screen to remind you of the mode.