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Calculators: Handheld: Commodore F4902

Size (approx):

80mm x 147mm x 20-40mm  (w,h,d)
Weight 124g excluding batteries

Power: 9V DC, 1 x PP3 size battery. It accepts an adapter/charger located on the top side in the middle. Use adapter DC-505, 707, 708 or 709.  There is a power save function that switches the display off.
Case: Two-piece stippled black plastic case with silver printed trim. Raised brand name is also printed silver but has not survived well on this example.  Keys in light and dark grey, white and black with raised additional labels printed silver on the keyboard surround.  The keys are short travel squishy type but work very well.   Heavily inset and tilted red display filter works quite well giving a large bright display.
Display: 11 digit red LED with bubble lens with a twelfth digit for negative, error and statistical indication.  
Features: Four functions plus percentages, delta percentages, change sign, register exchange, powers, square root, reciprocal, brackets, nth root, squares, logs, statistical and financial functions and a four function memory.
Age: 1978
Manufacturer: Commodore.  Made in Hong Kong serial No. 14943 with another number 201449-04.
Comments: I think these are lovely as they are so strange now that spreadsheets do all the work for you. With 49 keys is this a button monster or what?  The F prefix of this period indicates a "Financial model", they used "SR" for Slide Rule (or scientific).  The "49" may refer to the number of keys and they have dropped the "D" for disposable battery version. Considering its sophisticated functions it is odd that there are no constants, no error recovery, storage of errors and a "divide by zero" bug.  Fabulous!

Components: 1 x cpu: MOS (logo) M867561 0041078 (but numbers not clear) 28 pin DIL, 0.6" width.
1 x LED with bubble lens display module
no other components
Boards: One board doubles as the keyboard and main cpu board (PCB No. 201478) and is fixed to the front by six screws.
Construction: Remove the two long screws from the rear and the back section lifts off easily, hinging from the bottom.

Logic comments: (C/CE) is used to cancel the last number entered and a second time to clear the whole calculator.
There is no constant function
Input overflow is suppressed, inputting a twelfth digit is ignored
Negative numbers are shown with a "-" in the far left (thirteenth) digit thereby allowing full twelve-digit negative numbers
Divide by zero shows no error - only zero and you can carry on calculating!
Overflow shows no number with "E" in the left (twelfth) digit and is not recoverable
Negative square roots show no result and "E" in the left (twelfth) digit and is not recoverable  
The change sign can be used in mid-number entry
Memory store is not indicated; you have to remember it
It is possible to store an error state in the memory; try entering 99,999,999,999 using (M+)(M+) the calculator continues quite happily but the error flag is stored!
There is a power save function; after about 60 seconds the display goes to a single (first digit) decimal point (except in th error condition where nothing is displayed).  Operation can continue by just pressing the next key you want - unlike the manual instructions (see below).
The (F) or function key is used to select the operation in the upper label
For those without a manual the financial keys stand for: (N) number of periods/payments, (i) interest rate, (PMT) payment, (PV) present value, (FV) future value, (CST) cost price, (SEL) selling price, (MRG) margin, (SLP) slope, (INT) intercept, (X hat) and (y hat) predicted values, (DLT) entry delete, (Xi) and (Yi) data entry keys, (x bar) sample mean, (S) and (S') standard deviation, (CFL) cash flow, (O/D)  ordinary / annuity due switch.
Using the data entry keys lights the left (twelfth) digit decimal point to remind you to enter the second data point (y).


The box to the left measures approx. 87mm x 155mm and is 47mm deep, so not much else than the calculator went in.  It is printed in red, blue, black and silver so no expense spared.  The sides have French and German text and it is printed in Hong Kong.

This may not be the correct box as the image shows some blue keys and states it to be a 12-digit calculator when it is actually an 11-digit plus minus sign.  Any info would be gratefully appreciated.


The manual to the left measures approx. 83mm x 147mm and is printed in grey and black with black only inner pages.  It is very extensive with 23 pages of "General Finance" information, 42 pages of operating instructions, 15 pages of appendices and 6 pages for notes.  A very useful "Key Index" allows you to look up the particular key of interest.  Wow!

There is a sticker on page 2 of the operating instructions revising the information about display shut-off (power save).  It states that "If the last key depression was of a function key or if left on Zero [sic] after switch on, no calculations [sic] is lost and the calculator can continue at any time. Press (X<>Y) twice to recall the number to the display."  This is not true on my example where just depressing the next function key will recover OK.  Perhaps this is the wrong box and manual?

Printed in Hong Kong, copyright 1978 by Commodore International Ltd.