Canon MD-8 Multi 8

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Calculators: Handheld: Canon Multi 8 (aka MD-8)

		Size (approx):	73/76mm x 155mm x 20mm (w,h,d) Weight 154g excluding batteries
		Power:	4.5V DC using 3 x AA size batteries. It accepts an adapter (4.5V DC 0.5W) through a socket on the bottom side to the far left.
		Case:	Made from a two-piece smooth black plastic case this calculator has two full size aluminium panels that wrap over the edges. The upper section is dominated by the neutral display filter which sits flat and flush. It has raised text painted white for the switch and key labels. It has to be fairly large to accommodate the two lines of display digits. The lower keyboard surround has black printed text for the brand and model name and the on/off switch label. Keys are Casio-like with individual escutcheons. They are bouncy and make a soft click and work well to this day.
		Display:	Upper display; 8 digit blue VFD with a ninth digit for a negative indicator and a tenth digit for the memory indicator Lower display; 8 digit blue VFD with a ninth digit for negative and error indicators and a tenth (nine-segment) digit for operator display
		Features:	Standard four functions with percentages, square root, register exchange, change sign and three function memory. Auto accumulate memory storage, memory display, calculation display.
		Age:	1977
		Manufacturer:	Canon Inc, Japan. Serial number 635262 is on a sticker on the inside of the battery compartment cover.
		Comments:	Pretty strange experiment by Canon. Two displays eat quite a bit of power as can be seen by the half-watt rating. However, it is very nice to use and nice to see the full calculation you have put in. This is a common feature on today’s “graphing” calculators. Considering the date, when calculators were being made as cheaply as they could – this was obviously an exception. Good solid feel with good logic except the lack of error recovery. Original case is soft black plastic with open top. It has “Canon” and an outline of the calculator shape embossed on the front and “Japan” embossed on the rear.

Components:	1 x cpu: Texas TMC1079NL KBSL 7714 (week 14 of 1977), 28 pin DIL, 0.6" width 1 x 2 line 10 digit VFD, single tube flat face module 1 x VFD symbol tube: line and dot display single tube, round face 4 x transistors 9 x diodes 8 x capacitors 13 x resistors 2 x resistor array 1 x transformer
Boards:	The keyboard assembly is fixed to the front with one screw and joined by 22 strong copper wires to the main board (Canon EH1-0115-03) which sits loose on top.
Construction:	Very difficult to open as the two pieces of the case are fixed by lugs only. High risk of damage trying to open it - so if in doubt do not bother. I found the easiest way was to use a finger nail to pop the top by pushing out the front section. Then travel down the sides and finally hinge off the bottom.

Logic comments:

(CI/C) cancels an incorrect numerical entry, pressing a second time clears the calculator

Input overflow is suppressed, typing in nine digits ignores the ninth

There is automatic constant on multiply and divide only

Negative numbers are shown by a minus in the immediate left digit travelling into the far left (ninth) digit thereby allowing full eight digit negative numbers.

The (SC) change sign function can be used in mid number entry

Divide by zero results in zero and an "E" in the far left (ninth) digit and is not recoverable

Overflow shows the result with "E" in the far left (ninth) digit and is not recoverable

Memory store is indicated with a "M" in the far left (tenth) position of the upper display except in single mode (see below) when you have to remember it yourself!

(RV) is register exchange and swaps the two numbers in an operation. It is not a memory control even though it is clustered with the other memory keys.

Negative square roots are not allowed, result is show with an error and is not recoverable

There is a switch labelled "AM" for automatic (or accumulation) memory. When this is set on every result of the "=" key is added to the memory.

There is a three way switch to set the operation of the calculator:

	Process shows the dual line calculation display; Keying in (6)(X)(9) shows "6" in the upper display, "9" in the lower display and "X" in the lower display's far left (tenth) digit. The latter digit can show "-", "÷", or "+".
	Single puts the calculator into single (lower) display mode only - just like a normal calculator. I guess this was put in to conserve batteries.
	Memory where the contents of the memory is constantly displayed in the upper display. The "M" character in the tenth digit position is always on in this mode even when the memory is zero