Vanguard X-802 Type I

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Calculators: Handheld: Vanguard X-802 (type I) (aka 12PA)


		Size (approx):	93mm x 170mm x 25-35mm (w,h,d) Weight 230g excluding batteries.
		Power:	9V DC, 6 x AA size batteries double-decker stacked. Also accepts adapter (three pin 9V+9V DC 90ma+120mA) through a top side socket on the far right. The battery compartment has a ribbon-pull to aid removal
		Case:	Large blocky calculator with pronounced raised top area to accommodate the six batteries. Constructed of a two-piece matt black plastic case with substantial side brushed aluminium panels. The two vertical raised edges are painted white. Two very stylish mini knobs sit in a grooved section with an obvious punch-out panel for a larger movement decimal point switch. The switch labels, along with the top section are printed white with the model number. The brand name is silver painted raised plastic. There is a tilted and very slightly proud red plastic display filter which is notable for being full-width when the display is actually a third of the width. The display is bright with a wide angle of view. The convex keys are short travel, loud hollow click type but work well to this day.
		Display:	8 digit red LED with bubble lens and a ninth digit for negative, input overflow and error indicators.
		Features:	Four function with percentages and switched constant.
		Age:	1974
		Manufacturer:	Vanguard, Cahue Industrial S.A. Spain. Serial number 50688 on a label inside the battery compartment.
		Comments:	Very stylish but cumbersome calculator from this Spanish manufacturer. This is one of two (that I know of) models named X-802 along with the Type II. From the look of the extra switch panel (and other models on this site) this is a generic case used for many calculators. Strange logic with use after input flow and dodgy constant function.

Components:	1 x cpu: Mostek MS5020BN 7436 T Malaysia (week 36 of 1974) 28 pin DIL , 0.6"width 2 x ICs: RCA CA3081 443 (and 430) (week 43 and 30 of 1974) 14 pin DIL, 0.3" width 2 x LED modules; 1 x 4 digit, 1 x 5 digit, red bubble lens units 4 x transistors 3 x diodes 31 x resistors 4 x capacitors 1 x transformer
Boards:	The main cpu board (12PA 214) is held to the front by two screws and sits on top of the keyboard assembly (12PA 560C 561o) which is held to the front by four metal spacer pillars. The two are joined by 13 wires.
Construction:	Remove the two screws on the back and the back section comes away easily. Gently pull out the front keyboard which hinges up from the top.

Logic comments:	The (CE) key is used to clear the last entry whilst the (C) key clears the whole calculator
	Overflow on the input of a number is not suppressed, typing in a ninth digit results in an overflow showing "C" in the far left (ninth) digit. However, calculations can still be carried on!
	The constant function is switched with the (K) switch on all four functions
	When the constant is switched on results can be a little unpredictable. Try (1)(-)(9)(=) to give "-8" then (X)(2)(=) will show "2"! I think this is because the constant factor is taken from the first number.
	Negative numbers are flagged by a "-" sign in the far left (ninth) digit thereby allowing full eight digit negative numbers.
	When used in isolation the percentage key will divide by one hundred, once.
	A divide by zero shows "0." and an upper "n" in the far left (ninth) digit and is not recoverable
	Overflow shows the result with and upper "n" (or an upper square if negative) in the far left (ninth) digit and is not recoverable