DECOMPOSITION.md 5.8 only named these as "standard pictured-output
definitions over UM/MOD and a hold buffer". They are now written out
(5.8) and run on the golden model.
D-13 (ruled 2026-10-03): the hold buffer takes 63 characters, as v3's;
HOLD of a value outside 0-255, or into a full buffer, stores nothing and
sets NODE-ERROR, which is what v3 did with its error flag.
Behaviour follows v3 otherwise: digits 0-9 then A-Z, BASE outside 2..36
reads as 10, SIGN ( n -- ). Stack effects are the standard ones, as 5.8
already ruled (v3 took its double low cell on top). The buffer is 64
bytes, filled backwards from its end through HLD; `#` divides by the
base in two UM/MOD steps. HOLD, SIGN and # end in a jump to the next
word instead of a call, which saves two return-stack entries: with
calls, the signed picture `.` needs overflowed the 9-deep return stack.
New test file v4/tests/test_pictured.c, on a node of its own:
test_foundation.c's hand-assembled words already fill 901 of a node's
1024 words. It re-assembles SWAP, OR, UM/MOD, LSHIFT, RSHIFT and C! as
they are in test_foundation.c.
Checked against a C reference (short division on 16-bit limbs) at 32-
and 64-bit cells, optimised and ASan+UBSan (`make test`, `make
sanitize`), 4716 checks per width: <# #S #>, <# # # 46 HOLD #S #> and
the signed picture, in bases 10, 16, 2, 8, 36, 3 and the invalid 0, 1,
37, -5, on every pair of 15 edge cells; HOLD of 12 values; and a base-2
number that overflows the buffer (63 characters kept, NODE-ERROR set,
nothing outside the buffer written). Six mutations all fail.
Headroom: <# #S #> leaves 3 data cells and 2 return entries; the signed
picture leaves 1 return entry. The depth is C!'s as written (C! ->
LSHIFT -> SWAP), which is unchanged.
Test results on the amd64 host only. This is a development check, not
acceptance (JUSTIFICATION.md section 16).
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
