Exercise 3: Explaining Three Chapter-Attribution Rows — Possible Solution
====================================================================

ROW 1: "ARRAY,X / (HL) with INC" -> cpu8bit1-4, cpu8bit1-7
------------------------------
The 6502 version reads each array element with LDA ARRAY,X, which is
zero-page,X indexed addressing exactly as cpu8bit1-4 taught it — the
array lives in zero page, and X supplies a changing offset each loop
pass. The Z80 version instead keeps a pointer directly in HL and reads
through it with LD A,(HL), incrementing HL each pass — the register-
indirect addressing cpu8bit1-7 introduced, which needs no zero-page
step at all.

ROW 2: "JSR/RTS and CALL/RET" -> cpu8bit1-3, cpu8bit1-7
------------------------------
Both subroutine calls in this capstone are the first time in the
entire course that either chip's real hardware stack actually gets
used by a running program, rather than just being described. JSR
automatically pushes a return address onto the 6502's page-1 stack
(cpu8bit1-3) before jumping to UPDATE_MAX, and RTS pulls it back off;
CALL and RET do the same job using the Z80's fully flexible 16-bit
stack (cpu8bit1-7).

ROW 3: "CMP/BCC vs. CP/JR NC" -> cpu8bit1-3, cpu8bit1-6
------------------------------
Both subroutines need to compare a candidate value against the
current MAX, and both do it by reading a Carry flag set by a
comparison instruction — the status/flag registers cpu8bit1-3 (the
6502's P register) and cpu8bit1-6 (the Z80's F register) each
introduced. The reason this row is worth its own dedicated line in
the table is that the SAME flag, set by superficially similar
instructions (CMP vs. CP), ends up meaning the OPPOSITE thing on each
chip — directly exercising the flag material both of those earlier
chapters built up.

WHY THIS WORKS AS AN ANSWER
------------------------------
It picks three specific rows, names the exact line(s) of capstone code
each one refers to, and explains — using each earlier chapter's own
stated material — precisely why that code needed that chapter's
concept, rather than restating the table's own wording without
connecting it back to the actual code.