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Let the reset button reach a machine that has stopped

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The gesture rebooted CosmOS and could not reboot picture.bin, which is the case it was added
for. picture.asm ends in HALT, and a halted machine runs no instructions - so nothing ever
reached the code that notices a reset, because a reset is noticed BETWEEN INSTRUCTIONS and
there are none. It only ever worked because CosmOS was still going.

Which is backwards: a machine that is not going anywhere is exactly the one worth restarting,
and it is the one that cannot hear a request by itself. The restart is lifted out of the run
loop into machineTakeReset, and the window asks every frame whether the machine is running or
not.

NAMED AS EMULATOR MAGIC, because it is. There is no reset line on this machine and no keyboard
controller to assert one; the window reaches in and sets the same flag the machine port sets.
When those are designed, a keyboard controller will have to see the gesture and pull reset
regardless of what the CPU is doing - which is the property that matters and the one a port
write can never have, since a port write needs a program willing and able to make it. The
shape of that is already visible here: asking every frame rather than leaving it to the
machine to notice is what a line does.

A restart now clears the cycle limit as well, since a machine stopped for reaching one is
another thing somebody would press the button over.

The three existing reset tests still pass, and they are the ones that matter: they exercise
the same restart through the machine port. What no test reaches is the gesture itself, which
exists only when there is a window.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01E2JrLzFvuFX9fgi1LDRjrW
This commit is contained in:
Anachronaut
2026-08-29 14:48:31 -04:00
co-authored by Claude Opus 5
parent 8c6ed62044
commit adefce975b
4 changed files with 79 additions and 21 deletions
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Source/Emulator/voyager.c
+14
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@@ -128,6 +128,17 @@ static void drainKeyboard(void) {
// ---- The reset button ----
//
// EMULATOR MAGIC, AND KNOWN TO BE. There is no reset line on this machine yet and no keyboard
// controller to assert one: the window reaches in and pokes the same flag a program pokes
// through the machine port. When those are designed, a keyboard controller will have to see
// this gesture and pull reset REGARDLESS OF WHAT THE CPU IS DOING - which is the property
// that matters and the one a port write cannot have, since a port write needs a program
// willing and able to make it.
//
// The shape of that is already visible here. A reset is normally noticed between
// instructions, and a halted machine runs none - so the window asks every frame rather than
// leaving it to the machine to notice, which is what real hardware would do with a line.
//
// ON REAL HARDWARE THIS IS NOT A KEY AT ALL. A Voyager has a button on the case, and what a
// window has instead of a case is a gesture. So the gesture wants two properties a single
// key does not have.
@@ -344,6 +355,9 @@ int main(int argc, char *argv[]) {
// it drew is still there to look at - a program that ends should not take its output
// off the screen with it.
while (windowOpen && !WindowShouldClose()) {
// Before the running check, not after it: a machine that has stopped is the one
// worth restarting, and it is the one that cannot notice a reset by itself.
machineTakeReset(&machine);
if (machineRunning(&machine)) {
machineRunSlice(&machine);
}