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Victor 1800 Desktop Calculator
Updated 1/6/2014
This Victor 1800 a part of a series of different machines in the line of 1800 calculators introduced by Victor Comptometer Corporation in 1971. Apparently a number of different machines were made under the '1800' designation, with varying model numbers and capabilities. The model number of this machine is 18-1441. The 18 signifies the 1800 series, with the first two digits (14) of the model number defining the number of digits of capacity of the machine, and the last digit signifying that the machine has one memory register. Apparently three different models of the 18-144x calculators were made, the 1440, with no memory functionality, the 1441 exhibited here with a single memory register, and the 1442, with an additional memory register. Other 1800-series machines were made, including two 18-154x series machines, the 18-344x printing calculators, and the 18-1721 Scientific calculator.
Inside of the Victor 1800
This machine dates from the late 1971 timeframe. It uses a 6 chip Large Scale Integration (LSI) chipset made by Rockwell for its brains. All of the LSI's are dated in the October 1971 timeframe, and other components in the machine share similar dating. This makes the Victor 1800 a fairly early LSI machine.
Closer View of Rockwell LSI's
The Rockwell chips
are numbered 10177, 10178, 10179, 10180, 10182, and 15000, and are packaged
in 42-pin ceramic packages. The chips are mounted on a fiberglass double-
sided circuit board, along with basic discrete support components such
as diodes, resistors and capacitors. The main brain board connects to
other areas of the calculator via flexible ribbon cables. Even the power
supply connects to the main board via a flexible cable. The power supply
and main board are mounted to the base of the case, with the keyboard,
display, and display driver circuits mounted to the top part of the case.
The Gas-Discharge Display of the Victor 1800 Hybrid Modules Used as Display Drivers The 1800 uses a gas-discharge display
panel similar to a Burroughs Panaplex, however, it appears to be made by
someone else (can't discern any manufacturer), and is of a somewhat different
design than the Burroughs panels. Burroughs Panaplex panels use a clear
metallized electrode in front of the segments, whereas this panel has an
wire grid (similar to that of a Nixie tube) in front of the segments.
The panel has 16 positions, with the right-most digit position used for
indicating sign (-), and the far left position serving as an indicator for
overflow conditions (F). The display panel has a fairly large circuit board
crammed with hybrid devices that serve as the display drivers. The hybrids
contain a ceramic substrate which contains passive components, along
with discrete high-voltage transistors which provide the high-voltage
switching to drive the gas-discharge display. Display digits are formed
out of nine segments. The standard 7-segment arrangement is modified
to add two vertical segments that allow
the '1' to be displayed centered within the digit. Each digit position
also contains a decimal point. The display logic performs both leading and
trailing zero suppression.
Victor 1800 Keyboard Layout The Victor 1800 is a four-function
calculator, with one memory register. The calculator operates pretty much
as expected for a machine of this vintage, with the [+] and [-] keys
operating adding-machine style. For example, to perform 10 - 8, one does
10 + 8 -. Multiplication and division use the [=] key to generate
the result. The machine has a full-time constant, which operates in all
four functions. This can be demonstrated by pressing "[1] [+]", followed by
repeated presses of the [+] key, which results in the display incrementing by 1
for each press of the [+] key. A constant in all four functions is a useful
ability that is not shared by many calculators from this era. The memory
functionality of the machine is quite nice, with [M+] and [M-] keys
adding/subtracting the content of the display to/from the memory register
without affecting the display. The [=+] and [=-] keys serve to terminate
a multiply or divide operation (like the [=] key), but also adds/subtracts
the resulting answer to/from the memory register, leaving the result of
the multiply/divide on the display. This is very useful for sum-of-products
types of operations. When the memory register is non-zero, a small round
indicator on the right side of the display panel (labeled "M1") lights.
Rounding out the memory functions, the [MR] key recalls the content of the
memory register to the display, and the [MRC] key recalls, then clears,
the memory register. The [EX] key exchanges the operands of math functions,
IE: [4] [÷] [8] [EX] [=] will result in 2 (having performed 8/4 rather than 4/8).
The [C ALL] key clears everything except the round-off setting, including
the memory register. The [C] key clears overflow indications, as well
as clearing the display to allow entry errors to be corrected.
The Unusual "Round" Function Setting (showing the machine is set to round to 9 digits behind the decimal) The 1800-series machines are full-floating
decimal point machines. The decimal point is automatically placed at all times
to provide maximum precision. However, the machines add an unusual twist
to the picture by providing a "Round Off" function. Two keys on the keyboard
with ∩ symbols on them, one [∩ SET], and the other
[∩]. These keys are used to set the position of, and perform, a round off
function. The [∩ SET] key, when pressed (see image above), switches the
display to show a single digit from zero through nine, indicating the current
number of digits behind the decimal point that the machine will round off to
when the [∩] key is pressed. Pressing any digit from zero through nine while
holding down the [∩ SET] key will set a new rounding position for
the machine. Releasing the [∩ SET] key restores the display to its
original content. Once a rounding setting has been established (the
machine by default powers up with the rounding setting at 2 digits behind
the decimal point), any time that the operator wishes the number on the
display to be rounded-off to the desired setting, the [∩] key is pressed,
and the number on the display is immediately rounded to the selected number
of digits.
Overflow Indication (F) The 1800 is a very fast machine, with
virtually instantaneous results, even on the "all-nines divided by one"
test. A guess would be that the all nines division takes perhaps 60 to 80
milliseconds...fast enough that the result seems virtually instant. During
calculation, the display is quiet, with no spinning of the digits or other
indication that the calculator is busy. The machine is very good about
detecting overflow conditions, by displaying an "F" in the left-most position
of the display, and locking the keyboard. Overflow detection is also
activated when division by zero is attempted. Pressing the [C] key when
overflow lockout occurs clears the display and the overflow condition.
This machine was found at a flea market
by my aunt, who was always on the lookout for interesting old calculators
for me when she was out treasure-hunting. The machine is in like-new
condition -- whomever owned it took very good care of it.
Total price paid: $0.10.
