Calculators: Handheld: Datacal II
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Size
(approx): |
77mm
x 125mm x 24mm(max) (w,h,d)
Weight 98g excluding batteries |
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Power:
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6V
DC, 4 x N size batteries, 75mA. It
accepts an adapter (undefined but 5mm plug, centre negative) through a socket on the right side in line with the (=) key. The battery life is
quoted as 20 continuous hours. |
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Case: |
Quite
unique compact style made from a two-piece matt white plastic case.
White and burgundy colour scheme is matched well by the small logo plate
that sits in its own recess. The red display filter is tilted at
about 20 degrees so it works well on the desk as well as in the hand and
gives a nice bright display. The on switch label is raised but
unprinted. The keys are soft-click short-travel type and work very
well. They are also slightly tilted as well as horizontally concave. |
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Display: |
8
digit red LED with bubble lens and no ninth digit
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Features: |
Standard
four functions, percentages and averages |
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Age: |
1974/5 |
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Manufacturer: |
No
manufacturer's name but the back panel states V.I.P Programs Co., 113
Rushmore St., Westbury, N.Y. 11590. Serial No. 400-112126. |
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Comments:
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I
believe this was made by Corvus (consumer division of Mostek) as it looks
exactly like the Corvus 400 of c1974 (and the Radio Shack EC-230 of
1976). Lovely compact design with a strange "N" key for
averages. Good logic only let down by seven digit negative numbers
and lack of error recovery. |
| Components: |
1 x cpu: Mostek MK5026(?)0N ASSB Malaysia 7451 L (week code 51 of 1974) 28 pin DIL, 0.6" width
2 x ICs: ITT 501-5N 7409, 14 pin DIL, 0.3" width (possibly display
drivers)
1 x 8 digit LED display unit with bubble lens (HP dated 7443)
1 x diode
2 x capacitors
1 x resistors
1 x transformer; Mostek DC-10 1013 |
| Boards: |
The
keyboard assembly (ref KB3139 5015) is attached to the front via 9 plastic
lugs. It is joined to the main cpu board by a 15-way ribbon
cable. The main cpu board sits on six plastic posts. |
| Construction: |
Remove
the two screws from the back and gently separate by hinging off the bottom
two lugs. Be careful it will be easy to damage and the top rear
section is very thin. If in any doubt don't do it. |
| Logic comments: |
(C) cancels an incorrect numerical
entry on the first press and clears the calculator on the second so it is
a CE/C key really |
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There
is automatic constant on all four functions |
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Input
overflow is not suppressed, inputting a ninth digit causes an overflow
which is not recoverable |
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Negative
sign is shown in the immediate left hand digit but as there is no ninth
digit you are limited to seven digit negative numbers |
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Divide by zero shows a flashing
"0" and is not recoverable |
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Overflow
is shown by a flashing result and
is not recoverable |
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The (N) key is used for
averages; to find the average of 3,4 and 5 key in (3)(+)(4)(+)(5)(/)(N)(=)
and it displays "4". The (N) key retrieves the number of
numbers you have added in a chain. |
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Percentage key just divides the
current number by 100 |
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Considering how nice the calculator is - you
couldn't get duller than this! The box measures 110mm x 190mm
and is 40mm deep. It is made of quite stiff white card with a full
pull-off front half. There is one solitary blue sticker on the front
and nothing else. Why blue?
Inside is a complex-fold tray that holds the calculator with a foam
protective piece.
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That's better, at least the manual
matches! It measures 88mm x 140mm with a burgundy and
yellow printed cover and black pages inside. It has 18 printed pages
in total, two off which are a tear off warranty card with perforations.
It has quite a few clear examples and a lot
of descriptive text with a good diagram of the calculator keys.
It has a date of purchase (which matches the
serial number of this example) of 21 February 1975.
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