Craig 4505

		Home New Stuff Author Links Guest book Web-log	Adverts Bric-a-brac Calculators Components Ephemera Events	For Sale Glossary History Hit or Miss Radios Transport	Ultra Vales Wanted Metal Puzzles Articles Clocks

Calculators: Handheld: Craig 4505

	Size (approx):	157mm x 73mm x 31mm (w,h,d) Weight 180g excluding batteries
	Power:	6V DC, 4 x AA size batteries. It accepts an adaptor/charger (Craig 9227, 6V DC centre negative) through a socket on the top side in the middle. Rechargeable batteries will charge even when off, charge time quoted as 24 hours. I assume that you will need to remove standard batteries if using an adaptor. Low battery power is indicated by all decimal points alight.
	Case:	Horizontal format two-piece case in black patterned plastic. The top and bottom edges are gently rounded giving it a quality feel. The display to the left is a raised section which is slightly tilted. There is a black printed metallic sticker in its own recess with the brand name. The neutral plastic display filter is inset and gives a good clear image. The keys are long travel, quite springy with a prominent musical metallic click on return. The switch labels and LED border are raised and silver painted - and have not survived well on my example. The two end panels are heavily ridged black plastic.
	Display:	8 digit blue VFD with a ninth digit for negative and overflow indication. Additional single red LED for memory indication.
	Features:	Four standard functions with percentages and two function memory. Switched auto-memory and fixed decimal modes. Semi RPN logic.
	Age:	1973
	Manufacturer:	Craig Corporation, Compton, California 90220, USA, made in Japan. Serial number 0507028.
	Comments:	Well built horizontal format calculator from this early brand. The logic is not that bad but the archaic RPN input and pseudo decimal bug let it down. The original case is soft black plastic with a 1/5th side, top and 4/5th side zip. It has silver printed "Craig" on the front and a black plastic carry strap. this appears to be a later clone of the Telatronic SM8.

Components:	1 x cpu: Rockwell 15330OC 7324 (date code week 24 of 1973), 42 pin staggered DIL, 0.6" width 1 x 8 digit plus "E" digit VFD; single tube round face 6 x transistors 8 x diodes (on main board) 7 x diodes (on keyboard) 7 x capacitors 21 x resistors 1 x variable resistor 2 x rectifiers: KD-214S 3FG (date code June 1973) 1 x transformer with mini board for power components
Boards:	The keyboard assembly (B 013211) is attached to the front of the case with five screws. The main board (SM-003-D) sits in the rear of the case held in place by four plastic pillars, glued in place. The two are joined by 14 flying wires.
Construction:	Remove the screw from the rear and the back will lift off hinging at the bottom to preserve the link cables.

Logic comments:	The (C) button is used to clear last entry of a number whilst a second press clears the whole calculator
	Overflow on number input is suppressed, typing in a ninth digit is ignored
	An overflow shows the result and "C" (or "E" if negative) in the far left (ninth) digit and is recoverable using (C)
	Divide by zero shows zero and "C" in the far left (ninth) digit and is recoverable using (C)
	The logic is semi-Reverse Polish Notation: to do 3-4 key in (3)(+)(4)(-)
	There is automatic constant on multiply and divide (first entry for multiplication, second for division and last entry for addition or subtraction)
	Negative numbers are shown with a "-" in the far left (ninth) digit thereby allowing full eight digit negative numbers
	The percentage function can be used to mark up or down: to take 5% off 50 key in (5)(0)(X)(5)(%)(-) to give "47.5"
	There is switched floating decimal mode [AF], fixed two digit mode [2] and financial input mode [A2]. The latter causes the input of (1)(2)(3) to become "1.23".
	It suffers the pseudo fixed decimal bug: key in (1)(+)(.)(0)(0)(0)(+) to give "1.000" which remain a fixed three digit decimal number until you need more digits or you use multiply or divide
	The memory is switched on and then every press of (=) or (%) accumulates to memory
	Memory store is indicated with the individual red LED

This image shows the front of the case removed. The main board sits deep down to the side of the battery compartment. Typical early calculator with loads of components, many of which, like the power transistor in the middle and the large rectifiers, are a bit of an overkill for the power hungry vacuum fluorescent display. Notice that the have cut out a hole for the main IC which is mounted from beneath with the legs bent horizontally. The two bunches of wires at the bottom connect to the keyboard assembly.