Compex BJ-21 Black Jack

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Calculators: Handheld: Compex BJ-21 (aka Black Jack Calculator)


	Size (approx):	80mm x 142mm x 12mm (w x h x d) Weight 110g not including batteries.
	Power:	4.5V DC using 2 x AAA size batteries. It accepts an adapter (4.5V DC 0.3W) through a socket on the bottom side to the far left.
	Case:	The slim and tall case is two-piece smooth dark brown plastic almost completely encased in two wrap around brushed aluminium panels. It is gold tinted (although the scan on the left doesn't show this well). The front panel is printed in black text, labels and decorative symbols. The green plastic display filter is flat, practically flush and has its own black plastic escutcheon. The colourful concave keys are short travel clicking type and work a little unreliably.
	Display:	10 digit blue VFD with an eleventh digit for negative and a twelfth for black jack and error indicators indicators.
	Features:	Standard four functions with square root and one level of brackets
	Age:	1978
	Manufacturer:	Nam Tai Electronic Company Ltd., 1007-1008 Hang Shing Bldg, 363 Nathan Road, Kowloon, Hong Kong. Serial number from the rear sticker 01008, part number 943083.
	Comments:	Solid feeling heavy calculator with posh gold tint. A number of different brand issued similar models - all made by the same people judging by the generic manual. The calculator is basic but with ten digits and good logic it is useful. The Black Jack is, well, Black Jack. The original bill-fold style wallet in brown plastic has a pen holder, slot on the left for the manual and one on the right for a notepad.

Components:	1 x cpu; NEC D1021C K83216, 28 pin DIL, 0.6" width 1 x 12 digit VFD unit, single glass tube flat faced: Futuba 12-ST-22A 8D (suspect this is April 1978) 2 x transistors 6 x diodes 7 x capacitors 4 x resistors 0 x resistor arrays 1 x transformer: TDK CV-001
Boards:	The main cpu board (SH 560089 Zeny) sits loose on top of the keyboard assembly. The keyboard is joined by 16 strong copper wires and fixed to the front with plastic lugs. The main board has three cut-outs to allow the capacitors to sit within and reduce the width of the assembly.
Construction:	Quite difficult to open - try using a finger nail to pop one of the sides, gently squeezing in the back. Then pop the other side and carefully hinge off the rear from the bottom. If in doubt - don't force it.

Logic comments:	The (CE) key is used to cancel an entry whilst the (C) clears the whole calculator
	Input overflow is suppressed inputting an eleventh digit is ignored
	Negative numbers are shown with a "-” in the immediate left hand digit travelling into the far left (eleventh) digit thereby allowing full ten digit negative numbers.
	There is automatic constant on all four functions
	Divide by zero shows zero and “E” in the far left (twelfth) digit and is not recoverable
	Overflow shows the result and “E” in the far left (twelfth) digit and is recoverable by using (CE)
	Negative square roots are allowed and result in a negative number
	The percentage key in isolation will divide by 100
	In Game mode the display splits into two with the dealer being left to right and your hand being right to left. A full flashing display of zeros happens on a shuffle - cool!
	The black jack keys are as follows; (BET)- to place a bet value, (HIT)- to get another card, (STD)- to stand or stick with your cards, (INS)- insurance if the dealer gets an ace, (SPL) - to split a pair you are dealt with, (DBL) - double your bet to buy a card but only once, (TOT)- shows the total stake after a game

	The manual measures 70mm by 124mm and is 10 page fan-fold with the cover in green and remaining pages in black. It is in English only. Notice that the front image does not carry any branding so I suspect this is a generic manual. With just two pages devoted to calculator instructions, the majority of its focus is the game side. Part No. 920080