New Stuff
Author
Links
Guest book
Web-log
Bric-a-brac
Calculators
Components
Ephemera
Events
Glossary
History
Hit or Miss
Radios
Transport
Valves
Wanted
Metal Puzzles
Caravan
Calculators: Desktop: Hitachi KK 521
|
|
Size (approx): |
210mm x 250mm x 45-80mm (w,h,d) |
|
Power: |
Mains (220-240V 50/60Hz) power only through a detachable three pin connector. | |
| Display: | 12 digit blue VFD with three additional neon lights on the right for negative (NEG), Error (UDF) and Memory (M1) indicators. | |
| Features: | Standard four functions with register exchange and four function memory. Switches for rounding and fixed decimal and constant/accumulator | |
| Age: | 1972 | |
| Manufacturer: | Hitachi, but there is no label on my example to give the normal company name, country of origin and serial number. | |
|
Comments:
|
Very heavy and sturdy early 70s desktop that was built to last - and has. Quirky knobs and good bright display adds to the attraction of the Hitachi range of desktops. Odd "M1" name for the first and only memory. The fact that there is no floating point mode show how early this machine is. There was an earlier version of this model with orange nixie tube display and numbered digits. Hitachi supplied a very similar model to be branded as the Singer/Friden EC1117A. |
| Case and Design: | The base and top section is made of matt black plastic whilst the third display/edge section is matt light grey plastic. The steeply angled neutral display filter is deeply inset to give a clear bright image. A thick plastic embossed label sits on the front edge with the brand and model number printed silver. A full width black plastic handle pulls out from the lower front. |
|
|
| Keys and Switches: | They keys are well laid out, large hollow sounding click with long travel. Two switches to the far left switch on/off and rounding (5/4 for round and V for round down). There are also two rotary switches. The first is labelled O Sigma1, K and Sigma1K. This switches between auto memory accumulation and constant. The lower knob switches between zero and seven fixed decimal places, there being no floating point mode. |
| Construction: | Remove the two long screws from the underneath and the two short screws from the top side. The whole front section will come off easily, hinging from the top. The base is extremely sturdy and needs to be for the whopping transformer. |
|
|
| Boards: | The main keyboard assembly (Hitachi HPCB-E-147) is fixed to the front with 15 screws and is a very heavy, metal rimmed unit. Mounted on the surface board are reed relays which you can see the passing magnet switch - great for repairs. It is connected to the main cpu board by a bunch of 25 wires on a 44-way edge connector. The metal rimmed cpu board (Hitachi HPCB-E-47) is fixed to the base by a number of plastic brackets. |
| Components: | 3 x cpu: Hitachi
HD3234P 2G, HD3235P 2F, HD3236P 2F (June/July of 1972), 28 pin DIL, 0.6" width 2 x ICs: Hitachi HD9005 2E, HD2901P 2F, 16 pin 0.3" width 4 x ICs: Hitachi HD3233P 2F, HD3248P 2F, HD3233P 2F, HD3253 2F, 16 pin DIL, 0.3" width 2 x ICs (I think): 6255 727 and 6264 727 12 x single digit VFD tubes with 3 x neon indicators 8 x transistors 29 x diodes 13 x capacitors 46 x resistors 1 x variable resistor 1 x mains transformer 2 x fuses |
|
| Logic comments: | (CI) is used to cancel the last number entered and (C) to clear the whole calculator. |
| Input overflow is suppressed, inputting a thirteenth digit is ignored | |
| Constant function is switched in with the "K" switch and operates on multiple and divide only | |
| The rounding switch can select round down (V), round up/down (5/4) | |
| The decimal point switch can be selected between zero and seven decimal places, but not floating | |
| Negative numbers are shown with an individual neon light to the right of the main display thereby allowing full twelve digit negative numbers | |
| Divide by zero shows no display except the error (UDF) neon and is not recoverable | |
| Overflow shows the result and the error (UDF) neon and is recoverable using (CI) if the constant function is switched on | |
| Memory storage is indicated by an individual neon to the right of the main display | |
| The memory functions are labelled M1, when in fact there is no M2 (or second memory) | |
| An overflow in memory appears to clear the memory | |
| The register exchange key (R) exchanges the answer for the first number entered | |
| The add and subtract keys are rather archaic RPN. To do 3-4 you input (3)(+=)(4)(-=) | |
| The memory accumulation switch is also the constant switch. In Sigma mode all results from an equals key will be added to memory. In Sigma-K mode the constant is on as well. | |
| This calculator suffers the negative zero bug; try (1)(+=)(2)(-=) to give "-1" now add one by (1)(+=) will give "-0" |
