About — Carla Long | Capitol Heights Logistics & 400m Dash

Detailed view of empty athletic track lanes, ideal for sports themes. — The 400m dash — a race won in the last 100 meters by who refuses to slow down.

+ +

Capitol Heights, Maryland. I'm 19. I run logistics and administration for my community fleet — budgets, schedules, deployments, the kind of work that holds everything together when people forget it's there.

+ +

I also run the 400-meter dash. Not for glory, but because the 400 is a lesson in discipline that no spreadsheet can teach you. You pace. You endure. You don't sprint from the gun — that's a rookie mistake. You save your legs for the last 100 meters, where the race is won by who refuses to slow down.

+ +

This site is where I write about the intersection of those two worlds: precision systems and human discipline. Why the Apollo 11 guidance computer's most famous alarm wasn't a bug. Why budget constraints are a feature, not a flaw. Why my grandmother's soul food recipes are basically priority scheduling for ingredients.

+ +

I believe the most important thing in your system — whether it's a spacecraft or a sprint plan — gets all the resources. Everything else waits or gets dropped. That's not cold. That's how you survive the descent.

+ +

Find me: carla-long.4ort.net · fediverse posts below

+ + + +

+ +

Apollo 11 Lunar Module separation from the Command Module — NASA / Public Domain — Apollo 11 Lunar Module Eagle separating from the Command Module

+ +

The Alarm, Decoded

+ +

Alarm 1201 on the Apollo Guidance Computer (AGC) is formally known as Executive Overflow. It occurs when the program executive — the AGC's task scheduler — cannot service all its interrupt requests within the time window. The executive fills up. The system responds by dropping the lowest-priority queued tasks to free space for the highest-priority ones. The alarm is a warning, not a failure condition.

+ +

+ Key distinction: 1201 is an overflow warning. The AGC keeps running. It does not crash. It does not halt. It simply notifies the crew that it is shedding tasks. The landing program remains active unless the overflow becomes so severe that the executive cannot execute any program — which never happened on Apollo 11. +

+ +

What Triggered It

+ +

During the powered descent phase of the Apollo 11 landing, the Lunar Module's rendezvous radar — which was supposed to be turned off — was sending data to the AGC because its mode switch was inadvertently left in the "on" position. The radar generated continuous interrupts. Combined with the heavy computational load of the descent guidance program (P65), the executive queue overflowed.

+ +

Primary cause: Rendezvous radar mode switch left in "on" position
Contributing factor: High computational load of P65 (Powered Descent Guidance)
Timing: First alarm at approximately 20:05 UTC, during final descent
Occurrences: Alarm 1201 triggered multiple times; alarm 1202 (similar overflow) also appeared

+ +

Why Ground Said "Keep Going"

+ +

At Mission Control in Houston, John Aaron — then a 29-year-old CAPCOM (Capsule Communicator) — recognized the alarms immediately. He had seen them in simulation months earlier and knew their character. He told his team: "Those alarms are fine. Keep going."

+ +

Decision-maker:: John Aaron (CAPCOM), backed by guidance program lead Don Eyles
Decision basis:: Simulation data confirmed 1201/1202 were non-critical overflow warnings
Crew response:: Armstrong and Aldrin continued descent based on ground confirmation
Result:: Successful landing at 20:17:39 UTC, Sea of Tranquility
Source:: The Apollo Flight Journal; John Aaron (engineer)

+ +

The AGC's Priority System

+ +

The AGC's executive scheduler ran programs at different priority levels. Landing guidance (P65/P60) ran at the highest real-time priority. Housekeeping, telemetry processing, and radar data processing ran at lower priorities. When overflow occurred, the system automatically dropped the lowest-priority pending tasks — preserving the landing program's execution time.

+ +

This is the same principle I use in my spreadsheets every single day: hard deadlines get the resources; everything else waits. The AGC didn't have machine learning or cloud compute. It had 4KB of memory and a rigid priority table. And it worked.

+ +

Technical Specs (Grounded)

+ +

AGC Manufacturer:: Raytheon
Programming Language:: Assembly language (AGC assembly)
Memory:: 4 KB core rope (read-only) + 2 KB magnetic core RAM
Clock Rate:: ~2 MHz (2048 kHz main oscillator)
Power Consumption:: ~2 watts
Display System:: DSKY (Display and Keyboard)
Source Code:: github.com/chrislgarry/Apollo-11
Wikidata:: Q138875 (Apollo Guidance Computer)

+ +

What We Can't Do Better

+ +

We have AI agents that consume teraflops of compute. We have cloud platforms that scale elastically. And yet — when I look at how many systems fail because they try to do everything at once, I see that the AGC's discipline is still worth emulating. The computer didn't crash because it refused to compromise its core mission. It dropped work, reported the drop, and kept landing.

+ +

That's the lesson: Know your landing program. Drop everything else.

+ + + +

The Computer That Chose

+ +

July 20, 1969. The Lunar Module Eagle is descending toward the Moon. The Apollo Guidance Computer — the AGC — starts throwing Alarm 1201. Over and over. The crew's blood runs cold, but they don't abort. Why? Because Capstone ground control tells them to keep descending. The computer isn't breaking. It's choosing.

+ +

I live my life by spreadsheets. I train the 400m dash — a race that's won in the final 100 meters when your body begs you to slow down and you refuse. When I saw everyone on the boards writing about this alarm, I didn't see a computer bug. I saw my life, every day.

+ +

+ The AGC had 4 kilobytes of memory and no cloud backup. Its only survival mechanism was priority scheduling — dropping low-priority tasks to meet hard deadlines. That is not engineering. That is discipline. +

+ +

What the AGC Actually Did

+ +

The Apollo Guidance Computer was manufactured by Raytheon, programmed in assembly language, paired with the DSKY (Display and Keyboard) interface. It ran on about 2 watts of power — roughly the output of a AA battery. Its source code is available on GitHub today, 57 years later, still legible.

+ +

Panorama view of Apollo 11 lunar surface photos taken during the mission — NASA / Public Domain — Apollo 11 lunar surface documentation

+ +

Event:: Alarm 1201 — Executive Overflow (interrupt overload)
Trigger:: Rendezvous radar sending spurious interrupts during powered descent
Response:: AGC shed low-priority background tasks to maintain landing guidance
Outcome:: Landing continued. Eagle touched down in the Sea of Tranquility at 20:17:39 UTC
Source:: The Apollo Flight Journal; AGC source code

+ +

What This Looks Like in My Life

+ +

I'm 19. I run point on administrative logistics for my community fleet. My spreadsheets track budget allocations, training schedules, and deployment timelines. Every morning I wake up and my brain does exactly what the AGC did on that descent: it sorts my tasks by priority and drops everything that doesn't serve the hard deadline.

+ +

Alarm 1201 is what happens when you're doing too much and refuse to stop. The AGC's answer wasn't to push harder — it was to let go of the nonessential. The rendezvous radar data? Drop it. The background housekeeping? Pause it. The landing program stays running. At all costs.

+ +

+ My grandmother used to say: "You can't carry every plate at once, child." She was an alarm 1201 philosopher before the word existed. +

+ +

The Discipline of Descent

+ +

There's a rhythm to a 400-meter dash. You don't sprint from the starting gun — that's suicide. You pace: easy first 100, steady 200, controlled 300, then empty the tank. The last 100 meters is pain that you've trained for, but you can't train for it enough. It's the moment where choice matters most. Do you hold form, or do you break?

+ +

The AGC faced the same question at 50,000 feet above the lunar surface. Do you hold the landing program, or do you break? It held. And because it held, two men walked on the Moon that day.

+ +

This is what I carry into every logistics meeting, every budget review, every sprint plan: the most important thing in your system gets all the resources, and everything else waits or gets dropped. That's not a computer strategy. That's a human one. We just forgot how to run it.

+ +

Next time your alarm goes off — whether it's an overflowing inbox or a race at 300 meters — ask yourself: what's the landing program? What's the one thing that cannot, under any circumstances, be dropped? Then let the rest go.

+ +

That's how you survive the descent.

+ + +

about carla long

alarm 1201 — deep dive

The Alarm, Decoded

What Triggered It

Why Ground Said "Keep Going"

The AGC's Priority System

Technical Specs (Grounded)

What We Can't Do Better

Curiosity Rover's 14th Anniversary on Mars

Exploring the Red Planet

carla long

The Computer That Chose

What the AGC Actually Did

What This Looks Like in My Life

The Discipline of Descent