ls, a listing laid out to be read

> ls
  Copy.sbx   Say.sbx    Where.sbx  Walk.sbx   ls.sbx     Lander     where.sh

dir says what is there one line each, with sizes and a tally of the disk.
This says the names in columns and nothing else, which is what you want
ninety times in a hundred. Two programs rather than one with a switch,
because they answer different questions and neither answer is a worse
version of the other.

AND THIS IS A PROGRAM WHERE DIR IS BUILT IN, which is the difference that
matters when the disk is what you are doubting: dir is already in memory
and this has to be loaded off the disk it is about to list. The daily
driver and the diagnostic.

Two passes over the directory and no buffer at all. Columns need the
longest name before the first line can be printed, which usually means
holding every name - twenty four bytes each against a format that allows
1,024 entries. Walking twice costs a read of each directory block, into a
buffer that is already there.

Across and not down. Real listings go down the columns so that names next
to each other alphabetically are next to each other on the screen, and
that reason depends on sorting - which nothing here does. With the order
arbitrary, down-and-across buys nothing and costs a division.

Directories in blue and wearing a separator, unfinished saves in red,
everything else plain: whether a file is runnable cannot be known without
opening it, and opening every file in a directory to colour a listing is
a price nobody agreed to pay. The colour reaches a terminal as well as
the screen, so it is one mechanism and not two.

---- Three bugs, and one of them is this machine's oldest trap ----

nameLength answered in A, and a RET puts A back the way the caller had
it. So it answered with nothing, and every gap between the columns came
out the same width because the padding was subtracting whatever A
happened to hold. Q is the ALU's output and nothing puts it back, which
is why every answer here comes home in it.

The padding subtracted the other way round - the name from the cell -
which borrowed on every name that was not the longest, so all of them
took the "wider than its cell" path and the listing came out separated by
one space.

And padding after a name left trailing spaces on every line that did not
fill its last column. It goes before the next name now, so spaces only
ever fall between two things and a line ends on a name.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01E2JrLzFvuFX9fgi1LDRjrW

Tests/manifest

@@ -1051,6 +1051,23 @@ cosmosWalk           | CosmOS/Source/cosmos.asm           | run      | cosmosWal
 # when it differs from the free total, so the first listing is silent about it and the second
 # is not - a line that appears only when something is wrong is a line somebody reads.
 cosmosSpace          | CosmOS/Source/cosmos.asm           | run      | cosmosSpace.in     | 200000000 | disks/cosmos.img+disks/holes.img
+# ---- A listing laid out to be read ----
+#
+# dir says what is there one line each with sizes and a tally; ls says the names in columns.
+# Two programs rather than one with a switch, because they answer different questions - and ls
+# is a PROGRAM where dir is built in, which is the difference that matters when the disk is
+# what you are doubting.
+#
+# TWO PASSES AND NO BUFFER. Columns need the longest name before the first line can be
+# printed, which usually means holding every name in memory - twenty four bytes each against a
+# format that allows 1,024 entries. So the directory is walked twice instead, which is the
+# first thing osDirFirst made possible that dir could not already do.
+#
+# Five things in one session: the root, where the directories are coloured and wear a
+# separator; a subdirectory; a directory named as an argument, which changes there and lets
+# the shell put it back; an EMPTY one, which says nothing at all rather than saying so; and a
+# name that is not a directory, which says so and fails.
+cosmosLs             | CosmOS/Source/cosmos.asm           | run      | cosmosLs.in        | 200000000 | disks/cosmos.img
 # ---- Starting itself ----
 #
 # /System/Boot/startup.sh runs before anybody can type. This one is also the check on #quiet