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Calculators: Handheld: Santron 722
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| Size (approx): | 72mm
x 123mm x 23mm (max) (w,h,d) Weight 98g excluding batteries |
| Power: | 3.0V DC, 2 x AA size batteries. It accepts an adaptor (surprisingly 6V 100/150mA part number 027/979 or 025/038) through a socket on the top side to the far right. |
| Case: | Two piece case in white and dark brown matt plastic which is gently wedged-shaped. The top area holds a dark brown printed metallic sticker with the brand and model number that sits in its own recess. A flat and flush green plastic display filter give a good clean image. The keyboard surround is a light-gold coloured metal panel with black printed text for the on/off switch label. The keys are very springy and work well. |
| Display: | 8 digit green VFD with a ninth digit for negative and error indicators |
| Features: | Four standard functions with percentages, square root, and pi |
| Age: | 1978 |
| Manufacturer: | Santron, no other manufacturing details other than a sticker that says made in Taiwan, Republic of China, no serial number that I can find. Part number 027/359. |
| Comments: | As the back label and manual are in German I'm assuming this is a German brand. Sturdy enough calculator with simple functions. The original case is soft black plastic with an open top. The logic is very good with full recovery and only let down by negative roots. The numbering on the main cpu board suggests that the generic internal boards were used for a variety of model numbers. |
| Components: |
1 x cpu: Texas TMS1045NL MT 7840 (week 40 of 1978), 28 pin DIL, 0.3" width black plastic 1 x nine digit VFD unit, flat face single tube: NEC LD8118 8B (February 1978) 2 x transistors 5 x diodes 9 x capacitors 7 x resistors 2 x resistor arrays 1 x transformer: 246 |
| Boards: | The main cpu board (723A 724A 232) sits on top of the keyboard assembly which is fixed to the front with four screws and six plastic lugs, The two are joined by a 15 short copper wires. |
| Construction: | Remove the single screw from the rear. Loosen the power socket fixing ring. This doesn't help much as the case is held together with internal lugs. Quite difficult so be careful not to cause damage. I found the best way was to pop the single side lug by pressing in the white plastic while levering up and out the brown. Then try the two top lugs and the other side lug. Then carefully do the bottom lugs (mine would not hinge off so be even more careful. The back section will then come away - phew! |
| Logic comments: | The (C/CE) key on the first press can be used to clear the last entry whilst a second press clears the calculator completely |
| Input overflow is suppressed, keying in a ninth digit is ignored | |
| Negative numbers are represented with a “-“ sign in the far left (ninth) digit thereby allowing full eight digit negative numbers | |
| There is automatic constant on all four functions | |
| Overflow shows the result with “C” (or “E” if negative) in the far left (ninth) digit and is recoverable using (C/CE) | |
| Divide by zero shows zero and “C” in the far left (ninth) digit and is recoverable using (C/CE) | |
| Negative square roots are allowed and result in a negative number | |
| No other bugs found |
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This
image left shows the box 135mm by 80mm and 35mm deep, is just about big
enough for the calculator in its cover. It is a double tuck-end with
inner card former for added strength.
The two colour design is the same on both sides and there is no country of origin of other information. |
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| The
image above shows the manual which measures 119-123mm (yes it is badly
cut) by 77mm and is 20 printed pages. The cover is red and black
whilst all inner pages are black only.
The design tries to wow you with Pi, square roots, percentages and... oh yes, cancel keys! Plenty of examples and instructions in German language only. Reference number 635/0541/5/77/0.
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