Sanyo Model ICC-1122, S/N T7103240
Functions: ASMD, constant, total, 1 memory
Technology: MOS-LSI, portable (mains power)
Display: 12 digits, fixed decimal, 7-segment neon
Dimensions: 9"W x 5-1/2"D x 2-1/4"H, weight 3 pounds
Manufactured: Sanyo, Osaka Japan, 1971
The Sanyo ICC-1122 is a very early example of MOS-LSI technology in a portable calculator - although the unit could easily be mistaken for a transistor radio.
The single circuit board is located in the lower half of the case,
with plug-in connections to the keyboard and the power transformer. The
transformer module includes a moulded-in mains socket and voltage
selector, with the setting visible through a perspex window in the botom
of the case.
The keyboard uses sealed glass reed switches operated by moving
magnets attached to the ends of the keys. The keyboard and the four
slider switches can be removed as a single plug-in unit.
Overall, the calculator gives the impression of being a very clean,
simple, and accessible design.
The calculator is built in a rectangular plastic case
with an anodised metal trim. The carrying handle folds underneath to
act as a stand.
The bright 12-digit display uses Sanyo "Eightron" 7-segment
gas-discharge tubes (part number SMI-01, 10mm dia x 25m long). The 12
tubes are mounted in rubber grommets and driven by Toshiba high-voltage
modules (3 x T4105, 2 x T4106, located behind the display).
The power supply (lower left) uses an on-board oscillator
to provide the high voltage for the display, as the double-insulated
transformer module has only a single plug-in secondary winding. The
mains input is rated at 220/240V, 8W. In keeping with the spirit of
the portable design, the plug-in mains lead is a good 12 feet long.
The circuitry is built around two MOS-LSI chips in 42-pin
ceramic flat-packs. The part numbers are Sanyo D231B and D232B. There
are 4 NEC suport chips (uPD354D, uPD355C, uPD233C, D10A), one
Mitsubishi M58217, and a dozen discrete transistors. The double-sided
circuit board has several cut tracks and hard-wired "corrections".
The memory keys (M+, M-, RM, CM) at the right of the keyboard
operate as we have come to expect.
CK is "Clear Keyboard", and CA is "Clear All" (except memory).
Addition and subtraction use the +/= and - keys in adding-machine
fashion, while multiplication and division use "algebraic" notation.
Zero as either divisor or dividend will lock the calculator with no
error indication.
The minus key also functions as a unary minus (ie, sign change) if no
other operations are pending, but if used at the wrong time it can produce
quite unexpected results.
To the left of the keyboard are three small slider switches. The
bottom "5/4" switch selects display round-off or truncation. The centre
"K" switch enables storing a constant for use in repeated multiplications
or divisions. The top "sigma" switch automatically accumulates the
results of successive multiplications or divisions in the memory.
The calculator has an unusual RC "Recall Constant" key that toggles
the display to show the stored contant. If the constant was stored for
muliplication, the recalled display will be right-aligned, but for
division it will be left-aligned and filled with trailing zeroes.
Pressing RC again will restore the original display.
The slider switch at the extreme left sets the number of decimal
places in the display to 0, 2, 3, 4, or 6. The calculator uses a fixed
decimal position, which severely limits its numeric range. A lamp to the
left of the display indicates overflow.
The operation of the ICC-1122 is fairly straightforward,
although (like most early calculators) it does have a couple of
peculiarities.