Digitron: db 803

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Calculators: Handheld: Digitron db 803

		Size (actual):	77.3mm x 139.0mm x 37.7mm(max) (w,h,d) Weight 128g excluding rechargeable batteries
		Power:	6V DC, 4 x AA size rechargeable batteries. It accepts an adaptor by use of the supplied integrated case/cradle through three copper connections on the reverse (the two-pin plug is marked 2.5 250 [which must be a maximum plug rating rather than a consumption figure], Art 664, Esflex). My example had rotten old batteries, but you can put in standard 1.5V AAs OK. Rear of the case states the charger is 220V 50Hz, 6V DC, 250mA.
		Case:	The case is a two piece cream plastic construction with a heavily tilted (around 38 degrees) display section. The display area is covered by a red plastic filter that sits proud of the case and does a good job of obscuring some white text underneath it showing the digit numbers. Below this a small bordered section contains a gold printed raised model name. A printed red dot sits to the right of the on/off switch. The colourful keys are short travel with a soft click. The usual "bump" on the five being replaced by a ridge. The top left key is actually a slide switch.
		Display:	8 digit red LED (with straight horizontals and dotted verticals) and a ninth digit for negative and error indication
		Features:	Standard four functions with percentages and switched fixed decimal point
		Age:	1974
		Manufacturer:	Digitron, made in Yugoslavia, serial number 753708 and (I think a QA sticker) RSO ATEST N° Z-753708
		Comments:	Gorgeous and quirky design. Yugoslavia (at the time) did not have any import restrictions from the USA, so must have been one of the earliest (legitimate using US chips) calculator producers in that area. Having all the power/charging circuit in the case allows the design to minimise the components inside the calculator, which is surprisingly small and simple for this date.

Components:	1 x cpu: Mostek MK5020BN ASSB Malaysia 7436 E (week code 36 of 1974) 28 pin DIL, 0.6" width 2 x ICs: F SN75462N 7349, 14 pin DIL, 0.3" width (display drivers) 1 x 9 digit LED display unit 2 x diodes 1 x capacitor 2 x resistors 1 x voltage transformer 1/7431 (likely to be a date code rather than a part number)
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 battery compartment cover by levering the top tag underneath the large plastic label. The battery compartment can be lifted out by sliding it down and out. The main keyboard assembly can then be seen (KB3151 4346 OP243), fixed to the front of the case via five melted plastic posts. Then remove the two rubber lower feet and you can access to two "tamper protected screws". These are filled with (I think) paint to show if the calculator has been opened. Lift of the rear section, pivoting around the top edge lug. The small main board (Digitron 90040011) is joined to the keyboard assembly by 16 long wires and affixed to the front by two screws.

Logic comments:	(C) clears the calculator, there is no cancel entry function
	There is automatic constant on all four functions
	Input overflow is not suppressed, inputting a ninth digit causes an overflow which is not recoverable but you can still carry on calculating
	Negative sign is shown in the far left (ninth) digit thereby allowing full eight digit negative numbers
	Divide by zero shows an "r" in the far left (ninth) digit and "0." and is not recoverable
	Overflow is shown by the (non shifted result) and "r" in the far left (ninth) digit and is not recoverable
	The "F" switch is used to enable two decimal point fixed mode
	No bugs found

This image of the rear of the calculator shows how odd it is. Three copper connectors join up to the case-based connectors of the charging unit.

Additionally there is a very large label showing basic calculation examples.

You have to distort the top middle area of this rear label to open the battery compartment (the whole panel lifts off).

This image shows the calculator sat in its case with integrated charger. The hard, black patterned case with inner red felt-like lining has an upper section for the cable and two-pin plug. It has a white "Digitron" printed in the top. The lower section has a recess with three copper connectors for the calculator to sit in and a red LED for charge indication.

The case is hard plastic with a gloss finish and white "Digitron" printed in the top. The whole things oozes quality so must have been quite expensive in its day.