The Case of the Vanishing Blink

Tue, 20 Oct 2026 00:00:00 +0000

For years, picking an item on the Phosphor main menu did a small, satisfying thing: the row flashed — inverted video for about 150 milliseconds — and then the next screen took over. It’s a 65-byte courtesy. Two tiny frames: highlight the row, unhighlight the row, go.

Then one day the flash was just gone in Terminal.app’s telnet client. Not intermittently. Gone. MuffinTerm still showed it. The web client showed it, but only one flash instead of two. Three different clients, three different answers, one unchanged server. By the time we sat down to hunt it, every standard explanation had already been eliminated: the code was untouched since the feature shipped, the server was provably running the current build, the user’s preferences and theme tested innocent, and the same binary rendered the blink perfectly against a test instance. Same client, same server, same account. Different port. Blink on one, gone on the other.

Synchronized Updates and Frame Coalescing: How Phosphor Paints Atomic Screens

Mon, 19 Oct 2026 00:00:00 +0000

A BBS screen is a grid of characters, and for as long as character grids have flown over dial-up lines and TCP sockets alike, they have had one chronic way of embarrassing themselves: tearing. A full-screen repaint travels as a stream of cursor moves and color changes, and a client on a slow link — or a busy one — can catch the middle of it. You’ve seen the result: half the old screen with half the new one written over it, a status bar flashing the wrong colors for a tenth of a second, a table redrawn one row at a time like a document slowly printing.

Synchronization on Phosphor BBS

The Case of the Vanishing Blink

Synchronized Updates and Frame Coalescing: How Phosphor Paints Atomic Screens