Other Models not listed on this site but I have seen them (dates are mostly guesswork if "c" in front), four functions minimum is assumed

Model Number

Date

Features

200

c1978

8 digit VFD, square root, percentage, change sign, register exchange and four-function memory

200R

c1978

Same as 200 but rechargeable batteries

201

c1978

Like 200, but scientific model

202

c1978

Like 200 but with financial functions

203R

c1978

Like 200 but with square root, reciprocal and parenthesis

750 (NS750)

1977

Same as 835 but a) Six digit display, b) "L" on the left to indicate overflow, c) no percentage key, d) no square root key, e) no memory

832

c1976

Same as 842 but square root, percentages, change sign, register exchange but no memory

842

c1976

8 digit red LED, square root, percentage and four-function memory

850

c1976

Same as 850A

850A (NS850A)

1977

Same as 835 but a) no square root key, b) no memory

852

c1976

LED Scientific

900

1974

Same as 600, but white case

4525

c1977

aka "Scientist PR" LED, programmable scientific

4615

c1978

LED, programmable scientific, no exponent

4640

c1977

Same as 4615, 12+2 digit LED scientific

4650

c1975

Same as 852, 12+2 digit LED scientific

4660

c1978

Similar to 4615, scientific model

Mathematician

c1975

LED Scientific