Recently in CONTINUITY

Saturday, May 15, 2021

Chinese Tianwen-1 (天问) Lands on Mars

In vintage communist style, no streaming video or other contemporary coverage was provided of the landing, only this Stalinesque announcement after the (claimed) success, with the co-ordinates. Independent radio hobbyists have been tracking the telemetry signal from the lander and inferring mission events from its Doppler shift as it performed its final maneuvers and encountered Mars.

Posted at 10:11 Permalink

Friday, May 14, 2021

Andy Weir: Project Hail Mary, Writing, and Life

There are essentially no spoilers for the novel in this interview.

Posted at 16:12 Permalink

Thursday, May 13, 2021

A Mid-Air Collision with No Injuries

Posted at 13:56 Permalink

Wednesday, May 12, 2021

Darts in Higher Dimensions

This game/puzzle was originally suggested by Greg Egan, whose science fiction often features intricate mathematical constructs.

The problem is similar and related to, at a deep level, the “Sum of Uniformly Distributed Random Numbers”, about which I wrote in 2006.

Posted at 15:10 Permalink

Tuesday, May 11, 2021

Vacuum Tube Computer Part 12: Redesigning the Logic Unit and Building Buffers

After experimenting with an actual MC14500, it's decided to extend the design to support full binary arithmetic including carry, which on the original Motorola design requires lengthy bit-twiddling. Driving the resulting arithmetic and logic unit (ALU) will require more fan-out than the instruction decoder provides, so once again it's time to add buffer circuitry. At this point, the largely repetitive circuitry is complete, and it's time to contemplate the messy random logic which the ALU will require.

Posted at 11:43 Permalink

Bright Lights: The Story of Neon Signs

Geissler tubes filled with various gases that fluoresce when electrified were popular novelties in the 19th century, often made in whimsical shapes. If you have a Tesla coil, you really ought to have a few Geissler tubes which will light up in its vicinity without a wired connection. You can find them on eBay.

Posted at 08:55 Permalink

Sunday, May 9, 2021

SpaceX Starlink L27 Mission

SpaceX successfully launched Falcon 9 booster B1051-10 for the tenth time, achieving the original reusability design goal for the first stage, then recovered it on the drone ship. The mission successfully placed sixty more Starlink satellites in orbit.

Posted at 10:20 Permalink

Saturday, May 8, 2021

Long March CV-5B Re-entry Prediction Refined to ± 4 Hours

Re-entry will occur somewhere on the indicated ground tracks. The debris field will be extended along the track depending upon the mass and density of the objects that survive re-entry.

Posted at 14:33 Permalink

Friday, May 7, 2021

Scott Manley on the Flight of SpaceX Starship SN15

Posted at 17:04 Permalink

A Floating Ring in a Silicon MEMS Gyroscope

Here is the data sheet for the CRM100 [PDF].

Posted at 14:12 Permalink

Thursday, May 6, 2021

Garbage Then, Garbage Now—Microsoft Windows 1.04

The 640 Kb BIOS memory test at the start ran for 48 seconds on this IBM PC/XT clone (4.77 MHz Intel 8088). Testing the 16 Gb RAM installed on many current PCs at this speed would take more than two weeks.

Posted at 12:14 Permalink

Wednesday, May 5, 2021

Sixty Years Ago Today: The Flight of Freedom 7

Posted at 12:36 Permalink

Internet Security, 1990s Style, from General Electric

From the people who brought you the light bulb.

Posted at 12:15 Permalink

Tuesday, May 4, 2021

Freezing Water in a Sealed Container

Posted at 13:04 Permalink

1964—Mariner 4 Flyby of Mars

Here is more on Mariner 4. The film includes production of the “paint-by-number” manual production of the first image of Mars, which can still be seen at JPL today.

Posted at 11:38 Permalink

Monday, May 3, 2021

From 1966—RCA TR-4 Video Tape Recorder

Introduced in 1964, the TR-4 was larger than a big American refrigerator and cost, depending upon options, US$35,000 and up in 1966, or around US$290,000 in today's funny money. It used two inch wide tape on giant reels and was able, with an optional accessory, to handle colour signals.

Posted at 11:00 Permalink

Sunday, May 2, 2021

Rediscovery of the Coelacanth

Posted at 12:38 Permalink

HP 9825 Repair Part 6: Can the HP 547A Probe Get Us Out of Trouble?

As analysis progresses of the damage done to a 1970s vintage Hewlett-Packard (H-P) 9825 laboratory computer by a single shorted transistor in its power supply, one of the worst nightmares in digital circuitry debugging manifests itself: a stuck bit in an on-board bus. The stuck bit could be due to any of the numerous components on the bus, all soldered in place. To deal with this problem, in the 1970s, H-P introduced a piece of test equipment, the HP 547A current tracer. The idea was that by sensing the magnetic field of current flowing to the fault in the circuit, it would be possible to localise the fault on a bus with many components attached. Can this H-P gadget diagnose the fault in this H-P computer?

Posted at 11:57 Permalink

Friday, April 30, 2021

Chinese Space Station Begins Orbital Construction

Posted at 14:50 Permalink

Thursday, April 29, 2021

Mars Helicopter Ingenuity Fourth Flight

Posted at 11:51 Permalink