Calculators: Handheld: Commodore
F4902


Size
(approx):

80mm
x 147mm x 2040mm (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 DC505, 707, 708 or
709. There is a power save function that switches the display off. 
Case: 
Twopiece
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 20144904. 
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 twelvedigit 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 midnumber 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 12digit calculator when it is
actually an 11digit 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 shutoff (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.





