New Stuff
Author
Links
Guest book
Web-log
Bric-a-brac
Calculators
Components
Ephemera
Events
Glossary
History
Hit or Miss
Radios
Transport
Vales
Wanted
Metal Puzzles
Articles
Clocks
Calculators: Handheld: Rockwell 24RD
|
|
|
Size (approx): | 75mm x
155mm x 23mm (w,h,d) Weight 156g excluding batteries |
|
Power: |
6V DC, 4 x AA size batteries. Does accept an adaptor (undefined but 4mm plug centre positive worked fine) through socket on the top at the far left. | ||
| Case: | Sturdy stippled brown plastic case with light cream keyboard surround with brown printed text. A neutral plastic display filter site slightly inset to the case edges and gives a clear view of the numbers. Squashy but positive keys work well. The raised Rockwell logo and two vertical edges are painted silver and have not worn well in this example. | ||
| Display: | 8 digit blue VFD display with no ninth digit but two extra red LEDs above the display to indicate memory storage and minus sign. | ||
| Features: | Standard four functions, square root, change sign, percentages and four function memory. | ||
| Age: | 1975 | ||
| Manufacturer: | Rockwell international, Microelectronic Product Division, Anaheim, California 92803. Made in Japan. Serial No. 104155.25. | ||
|
Comments:
|
Classic Rockwell shape made that bit more desirable by the two isolated red LEDs. Original case is very high quality brown leather-effect with flip over top and tuck in band. Built to last - but pseudo fixed decimal bug and negative roots let the logic down. |
| Components: | 1 x cpu: Rockwell A5901CA 7551
(date code week 51 of 1975) 42 pin staggered DIL 1 x 8 digit VFD flat panel faced display; ISE DP89A 5927 made in Japan 2 x transistors 7 x diodes 9 x capacitors 2 x resistor arrays 9 x resistors 1 x transformer; DCT24 |
| Boards: | The keyboard assembly is attached to the front of the calculator via 12 screws and to the cpu board via 12 strong copper wires. |
| Construction: | Remove the two small screws in the battery compartment. Gently pull apart the sides and pull the front out (hinged at the middle. Pop off the display cover in a similar way. |
| Logic comments: | (CE/C) cancels an incorrect numerical entry, pressing a second time (C) clears the calculator |
| Input overflow is suppressed, keying a ninth digit is ignored | |
| Negative numbers are indicated by a pin-point red LED thereby allowing full eight digit negative numbers | |
| Overflow displays the shifted number with all decimal points lit and is recoverable by using (CE/C) | |
| Divide by zero shows "0.0.0.0.0.0.0.0." and and is recoverable by using (CE/C) | |
| It has automatic constant on all functions | |
| The change sign function can be used before, during and after a number entry | |
| Memory storage is indicated by a second isolated red LED above the display | |
| Overflow in memory is flagged and maintains the original number | |
| Negative square roots are allowed | |
| It suffers the pseudo fixed decimal bug: key in (1)(+)(.)(0)(0)(0)(=) to get "1.000" which remains a fixed three digit decimal until you need more digits or use multiply or divide |
