DATAMATH CALCULATOR MUSEUM
Heathkit Aircraft Navigation Computer OCW-1401
|Date of introduction:||1978||Display technology:||LED-modules|
|New price:||$169.95 / $274.95||Display size:||14|
|Size:|| 6.3" x 3.1" x
161 x 80 x 44 mm3
|Weight:||10.6 ounces, 302 grams||Serial No:||37313|
|Batteries:||4*AA||Date of manufacture:||year 1979|
|AC-Adapter:||Origin of manufacture:||USA|
|Precision:||Integrated circuits:||3 * Mostek MK3870|
|Program steps:||Courtesy of:||Joerg Woerner|
You are right - there is no connection to Texas Instruments! But - to be honest - it is one of the best engineered calculators.
If we trace back the Aircraft Navigation Computers back to
their roots we locate two different approaches:
Simple models introduced around 1980 like the Jeppesen Sanderson avstar or the prostar based on scientific calculators and more complex products like the USMC HARRIER based on programmable calculators.
This OCW-1401 started already in the year 1978 a third approach: Powerful Navigation and nothing else! Later products like the Navtronic Explorer (1983) and the Jeppesen Sanderson Techstar (introduced 1992) continued these kind of products.
You are familiar with this OCW-1401? Then you know the calculators sold by National Semiconductors. On a first view the calculator looks like a scientific calculator from National Semoconductor, e.g. the Model 4650. Indeed, the keyboard and the display of them are identical.
The OC-1401 was sold as kit, the OW-1401 was factory wired. Both included:
|• The calculator
• A glare screen for the display.
• A cigarette lighter plug for external power.
• A hard case to protect the equipment.
Dismantling this Heathkit OC-1401 Aircraft Navigation Computer reveals the complexity of the product. Three mask-programmed 8-bit single-chip microcomputers manufactured by MOSTEK (MK3870-MK14103 to 14105) and three other IC's (Fairchild F3539, National Semiconductors DS8664 and DS8667 display drivers) on a huge printed circuit board. To our knowledge the most complex pocket calculator ever produced - like most Heathkit products it was sold as a kit! A factory assembled version was available at $274.95. Find more information about the MK3870 here.
More astonishing is the usage of the calculator. In comparision to other flight computers you don't need a 100+ pages manual. Three modes are available:
|• Preflight: You have to key in all preflight data with the
Data is saved in standby mode while transport to airport.
• In-flight: You set the time and key in all necessary data with the yellow keys.
• Navigation: With the green keys you get all navigation data.
If we trace back in the history of electronic flight computers we discover: The Commodore N-60, this Heathkit OCW-1401, the navtronic 16 and the Texas Instruments TI-58 (with installed Aviation Modul). Heathkit published a small comparison table:
|Features||Heathkit OCW-1401||Commodore N-60||Navtronics 16||Texas Instr. TI-58|
|Flight Leg Entries||Up to 9||1||1||1|
|Continuos Data Update||YES||NO||NO||NO|
|Internal Program Built-in||YES||YES||YES||NO|
All were introduced in or before 1978, two years till the Jeppesen Sanderson avstar based on a Texas Instruments TI-35 appeared.
Don't miss the Tamaya NC-77 Astro-Navigation Calculator!
The 8-bit single-chip microcomputer MK3870 was introduced already in 1977.
In the beginning of microprocessor production Mostek was a second source of Fairchilds F8. Both designed one-chip microcomputers around the F8. Fairchild designed the F3859, which was a simple combination of the F3850 CPU and F3851 PSU on a single chip. Mostek developed a more ambitious one-chip microcomputer, the MK3870. Mostek developed this MK3870 ahead of the Fairchild F3859. Therefore, Fairchild dropped the F3859 and became a second source for the 3870.
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© Joerg Woerner, December 5, 2001. No reprints without written permission.