CRT Timing

How flash-frame and beam-timing guns read a CRT raster, the photodiode circuits redrawn, and why flat panels killed them.

Firearms

CRT Timing · Deep Dive

CRT Timing

The gun never sees the target; it sees the clock.

How flash-frame and beam-timing guns read a CRT raster, the photodiode circuits redrawn, and why flat panels killed them.

Photo: Macro of a CRT screen's red, green and blue phosphor stripes by Greg Hume · CC BY-SA 3.0

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    Volumes

    1. Vol 1 The Raster as a Clock — What a CRT Light Gun Measures, With the Numbers Line and frame timing for broadcast NTSC and PAL and for the consoles' 240p, the pixel clocks, how fast the spot moves across a real tube, and what the patch of screen a gun looks at turns into in time
    2. Vol 2 The Phosphor — What the Gun Is Actually Looking At The P-designation system, P22's three materials, their spectra, how fast they light and how slowly they fade, what a silicon photodiode makes of each, and why a light gun is nearly blind to red
    3. Vol 3 The Front End — Lens, Photodiode, Amplifier, Filter and Threshold How big a patch the lens sees and how much light it gets, photodiode against phototransistor, transimpedance bandwidth, the line-rate filter, threshold walk, and the classic guns' sensor chains redrawn
    4. Vol 4 Flash-Frame Detection — The Zapper Method in Timing Detail What a test frame actually asks, the frame budget per target, why the light must drain out during vertical blanking, the hit zone a box and a patch make together, the scan-line hybrid that recovers Y, and the property that lets this method survive a lagging display
    5. Vol 5 Raster Latching — Counters, Latches and the Jitter Budget What each console freezes and in what units, quantisation, every delay between phosphor and counter sorted into fixed and variable, the left-edge bias and the Menacer's eighth-line trick, the PlayStation's software latch, and a budget that reproduces Nintendo's eight-dot figure
    6. Vol 6 What Breaks It — Interlace, 100 Hz Sets, Line Doublers, LCD and OLED The four things a CRT gun needs from a display, and which of them each later display takes away: 480i's half-line offset, field memories and doubled line rates, sample-and-hold panels, scaler lag, and why no calibration can bridge the gap
    7. Vol 7 What Does and Does Not Work — Rescuing CRT Guns on Modern Displays Keeping a tube, flash-frame play on a lagging LCD and what it costs, why a beam-racing CRT simulator on a 480 Hz OLED cannot bring back a latch gun, what a display would need to, and the coded-frame idea that generalises the Zapper
    8. Vol 8 The Bench — Measuring a CRT, a Sensor and a Classic Gun Procedures for the Analog Discovery Pro ADP3450 that replace this dive's estimates with measurements: phosphor pulses by colour, the patch burst and photocurrent at range, sync-to-edge delay and jitter histograms, the Zapper's envelope, and the same sensor on a flat panel; plus a fault-finding order for a classic gun