More fills the screen it is on, not the screen it was written for

Twenty two lines was right when there was one screen size. It still is on
the forty column screen and wastes three fifths of the eighty column one,
so More asks the rows register instead - which is readable for exactly
this sort of reason.

Rows minus three is twenty two on a twenty five row screen, so nothing
changed underneath anyone already reading files this way. It fills a
bigger screen and leaves a smaller one alone.

A bitmap screen has no rows and says so with a nought, which through an
eight bit subtraction would be 253 lines. Anything under five falls back.

The existing test stopped testing paging the moment this worked: 32 lines
fits in a 47 line page, so the file never paged and the recording lost the
prompt entirely. The fixture is 60 lines now - the INPUT needed moving,
not just the output, which is the failure this project keeps meeting.

And cosmosMoreNarrow, which runs Mode first and pages the same file on the
forty column screen. Two recordings of one file at 47 lines and at 22: a
More that went back to a constant would make them the same length.

Both were verified with break.sh, and the first attempt was a bad break
rather than a bad test - it replaced one of two reads of the rows port and
the other still fetched the real value. Which is a fair argument against
reading a port twice, so it is read once and kept now.

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

Programs/CosmOS/Apps/More.asm

@@ -1,7 +1,8 @@
 ; Read a text file one screen at a time.
 ;
-; Twenty two lines are shown before a prompt. Space advances another screen, Return one
-; line, and q gives the machine back to CosmOS. This is forward-only on purpose: the file
+; A screenful of lines is shown before a prompt - as many as the screen has, asked for rather
+; than assumed, so that the eighty column mode is not read three fifths empty. Space advances
+; another screen, Return one line, and q gives the machine back to CosmOS. This is forward-only on purpose: the file
 ; stream holds one block and never asks the whole document to fit in memory.
 ;
 ; Written by ChatGPT for Anachronaut's SplitBit
@@ -100,11 +101,38 @@ pauseQuit:
   INIB 0x01
   OR
   RET
+; ---- As many lines as the screen has, less the prompt ----
+;
+; Twenty two was written when there was one screen size. It is still right on the forty
+; column screen and wastes half of the eighty column one, so this ASKS: the rows register
+; says how tall the screen is, and it is readable for exactly this sort of reason.
+;
+; Rows minus three is twenty two on a twenty five row screen, so nothing changed underneath
+; anyone who was already reading files this way - it fills a bigger screen and leaves a
+; smaller one alone.
+;
+; A BITMAP SCREEN HAS NO ROWS AT ALL and says so with a nought, which would come out as 253
+; lines through an eight bit subtraction. Anything under five falls back, because a page of
+; two lines is not a page and a program should not be the thing that discovers this.
 fullPage:
+  INA 0x33
   SETD.3 LinesLeft
-  INIA 0d22
+  STA.3                     ; Kept, because the sums below want A for themselves.
+  INIB 0d5
+  CCF
+  SUB
+  BRC fullPageFallback      ; Borrowed, so there are fewer than five rows.
+  LDA.3
+  INIB 0d3
+  CCF
+  SUB
+  MVQA
   STA.3
   RET
+fullPageFallback:
+  INIA 0d22
+  STA.3                     ; DP3 is still LinesLeft, from above.
+  RET
 
 noName:
   SETD.0 Usage

Programs/CosmOS/README.md

@@ -735,7 +735,7 @@ from every assembly file in it. Several are old programs written for the bare ma
 | Copy | Copies one path to another a block at a time, including an empty file or one larger than Data Memory. |
 | Compare | Compares two files a block at a time, stopping at their real tails rather than comparing unused bytes in the final disk blocks. |
 | Wander | Goes to the directory it is given and reads a file there by a bare name. The only thing that moves the machine from inside a program, and so the only thing that can check the shell puts the working directory back afterwards. |
-| More | A forward-only pager. Space advances a screen, Return one line, and q stops. |
+| More | A forward-only pager. Space advances a screen, Return one line, and q stops. A screen is as many lines as the screen has, asked of the rows register rather than assumed - 22 on the forty column mode and 47 on the eighty. |
 | Press | Says what the console handed it, in hexadecimal and by name. It reads a line and then keys, because the keys that are not characters are dropped in line mode and delivered in key mode, and both halves of that rule want showing. |
 | Crash | Breaks on purpose, in whichever of the four ways the system now catches, so that a fault screen can be looked at without having written a bug first. |
 | Mode | Forty columns or eighty, whichever the screen is not in. Ten instructions and no data at all, which is the point of it: it is the smallest shape a loadable program can take, and the loader used to stop the machine dead on one. |