| Manufacturer: | BUSICOM |
| Model: | 121DK |
| AKA: | exec, 121-DK |
| Year: | 1972 |
| Display: | Tubes (12) |
| Circuits: | LSI Chipset MOSTEK: MK6018, MK6019 |
| Dimensions: | 242x161x58 mm |
| Power type: | AC |
| Origin: | Japan |
| S/N: | 30QB142057 |
| Owner: | DEVIDTS Serge |
|
Feature |
Description |
Case: |
Plastic |
Color case: |
Beige |
Color keyboard: |
Black |
Weight: |
1100 g |
Voltage selection: |
No |
Adapter: |
No |
Power consumption: |
3.5 W |
Working condition: |
0 to 40 degrees C |
Printed Circuit Boards (PCB's): |
2 |
Memories: |
1 |
Memories indication: |
Via 'Memory' Neon bulb above display |
Prog. steps: |
N/A |
Decimal point handling: |
Via Switch on keyboard |
Rounding: |
Via Switch on keyboard |
Calculation overflow indication: |
Via 'Overflow' Neon bulb above display |
Input overflow indication: |
Via 'Overflow' Neon bulb above display |
Divide by Zero indication: |
Via 'Overflow' Neon bulb above display |
Negative value indication: |
Via 'Negative' Neon bulb above display |
Constant function: |
Via [=] |
Calculation speed: |
|
Auto Power-off: |
No |
|
Display details: |
|
|
Printer: |
N/A |
Extra features/remarks: |
When
overflow occurs and is cleared, the process, constant and memory contents
are retained. |
Initial price: |
|
Overall quality rate (1-10): |
8 |
OEM copy of: |
|
Other sources of info: |
|
Advertisements/Publications: |
Key / Switch |
Description |
EX |
Reverse
calculation, the first and de second factors/arguments are exchanged, |
CM |
Clear Memory |
RM |
Recall Memory |
CE |
Clear Entry |
C |
Clear |
0 to 9 |
Numeral keys |
. |
Decimal point key |
X |
Multiplication key |
(division) |
Division key |
+ |
Addition key |
- |
Subtraction key |
M (white) |
Memory key: |
M (red) |
Memory key: |
= |
Triggers the desired result |
9-6-5-4-3-2-1-0 |
Decimal
selector: |
N 5/4 |
Round mode Switch, (see: Decimal point handling and Rounding) |
M+- |
Memory mode Switch (see examples) |
Example |
Operation |
Display Result / remark |
Addition
and subtraction: |
|
(3 decimals) (Clear) -45.678 |
Multiplication: |
|
(3 decimals) (No rounding) 123.456 |
Division: |
|
(2 decimals) (rounding) 12.35 |
| Raising
Power (Constant): 3³ |
[Decimal Point switch]=0 3 [x] [=] [=] |
(No decimals) 27 |
Total
calculation: |
|
(3 decimals) (Memory addition mode) 1008 |


Display ^

Swicthes on keyboard ^

Internals ^

Internals ^

NCM (Nippon Calculator Machine Corp.) on bottom of PCB ^

MicroSwitch: smart solution to power up by opening the display deck ^

No LEDs, but small Nenon bulbs in 1972 ^
Handle ^

Label on top ^

Label on bottom ^

NCM (Nippon Calculator Machine Corp.) on bottom ^