The user's conversion, which I reverted while I was working out whether it was
half done or broken. It was half done: an sbx application wants its #Include
above #Program, because services.asm ends in a #Vectors block and a #Base
written after that has no segment to be the base of.
So the include moves up, the bases move a page with everything else, and the
test starts it from the shell instead of booting it. It plays for 9,469,987
cycles, 9,423,527 of them waiting, which is the same 567 frames of music it
played as a boot image.
BEING A PROGRAM MEANS ITS VECTOR IS THE SYSTEM'S TO INSTALL. It brings the
screen's, so that it has a beat to play to, and CosmOS puts it in when the tune
starts and takes it back out when it stops - a thing a boot image never had to
have right, and the second program here to exercise the version two format at
all.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01E2JrLzFvuFX9fgi1LDRjrW
CosmOS had 1,161 bytes of Program Memory left before the address applications
load at, and Tab completion is not going to fit in that with anything to spare.
So the wall moves up one page: the system keeps below 0x4FFF and 0x2FFF, and an
application is based at 0x5000 and 0x3000.
A PAGE IS A CHEAP THING TO GIVE IT AND AN EXPENSIVE THING TO RUN OUT OF. An
application still has 44K of Program Memory before the vector table and the
largest one here uses 7.5K, so what was taken from applications is space nothing
has ever asked for - while what the system gained is the difference between
building the next thing and counting bytes while building it.
Not doubling, which was the version that would have cost application space worth
minding. One page, and the same again when it is needed.
Nothing in the machine knows where the wall is, so this is 34 #Base lines, one
threshold in the fault handler, and the table in the CosmOS README that
Tests/docs.sh reads its limits out of.
The native assembler's scratch map had to move with it, and docs.sh said so
before anything ran: its data reached 0x40D6 and its buffers began at 0x4000, so
they were sitting on its variables. That file already carries a paragraph about
the floor coming up and the map staying where it was. It has happened twice now,
and been caught by a check the first time wrote.
Twenty three recordings are the same runs a page higher.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01E2JrLzFvuFX9fgi1LDRjrW
There was nothing at the end of the monitor's command list. An unrecognised word
fell off it and straight into sayPrompt - which is a ROUTINE, so its RET had
nothing of its own to return to and went wherever the Stack happened to be
pointing.
The user found it by typing a program's name at the monitor prompt, which is an
entirely reasonable thing to do: the monitor is a mode of the shell, so
everything the shell does is meant to work in it. What they got was a fault, and
before that a second prompt printed on top of the first - which is sayPrompt
doing exactly what it is for on its way past, and the tell that it had been
entered rather than called.
WHERE THAT RET WENT DECIDED HOW BAD IT WAS. Usually 0x0003, in the middle of
newLine, and the machine stopped on a byte that is not an instruction. Once it
was inside sbfsFormat, and the machine formatted the disk it had booted from -
the user's would not start again, and neither would mine, which is how I came to
have a reproduction before I had a diagnosis.
Pre-existing, and not recent: it is there at 2a29ceb and every revision I
checked back through.
The fix is one branch. cosmosMonitorRun covers all three cases the monitor now
has to handle - a program started by name, a program that faults, and a word
that is nothing at all - because the first of those is what the user did and the
last is what used to be fatal.
Worth naming as a shape: a run of tests falling through into a subroutine. The
symptom is not at the site, the failure depends on the Stack, and the damage is
whatever the return address happens to land on. SplitLint has no rule for it and
could have one.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01E2JrLzFvuFX9fgi1LDRjrW
AnachronautandClaude Opus 5