From 7274084cc07a473c530b129aa217f586781ba70c Mon Sep 17 00:00:00 2001
From: user <user@clank>
Date: Thu, 16 Jul 2026 15:45:09 +0200
Subject: syscall: mirror console output to the LCD terminal

KPutc's console path now renders each byte on the LCD terminal via
term_putc in addition to the serial write. Serial is kept so scripted
tests still capture output (and for link-cable/debug), while the shell,
command output, and echoed input now appear on-screen in the 40-col font
with a live cursor and scrolling. Dropped the boot-time term_demo; the
terminal starts blank and fills from real console traffic.

term_putc now saves/forces/restores SVBK=1 so it always reads and writes
the terminal buffer/state in WRAM bank 1, regardless of which process
context KPutc is invoked from (defensive; all procs currently use bank 1).
The stack lives in non-banked WRAM, so saving SVBK across the switch is safe.

Verified: a headless run of `uname; ls; echo hello world` renders each
prompt, the echoed command, and its output on the LCD (captured via the
new `--headless --shot` path), and serial capture is unchanged.
---
 src/boot.asm    |  2 +-
 src/syscall.asm |  4 +++-
 src/term.asm    | 14 ++++++++++++++
 3 files changed, 18 insertions(+), 2 deletions(-)

(limited to 'src')

diff --git a/src/boot.asm b/src/boot.asm
index ea52858..973bc8e 100644
--- a/src/boot.asm
+++ b/src/boot.asm
@@ -57,7 +57,7 @@ KernelInit:
     ld [wCurProc+1], a
     call fs_init                ; mount the disk (format on first boot; persists)
     call term_init              ; set up the LCD text terminal
-    call term_demo              ; cursor + scroll demo
+    ; terminal starts blank; shell output flows in via KPutc
 
     ; --- spawn the init task (pid 1); it fork()s the rest ---
     ld hl, TaskInit
diff --git a/src/syscall.asm b/src/syscall.asm
index 5557b5f..870a2ff 100644
--- a/src/syscall.asm
+++ b/src/syscall.asm
@@ -149,9 +149,11 @@ KPutc::
     jp sys_putb                 ; B=fd, E=byte
 .console
     ld a, [wKChar]
-    ld [rSB], a
+    ld [rSB], a                 ; mirror to serial (test capture / link)
     ld a, $81
     ld [rSC], a
+    ld a, [wKChar]
+    call term_putc              ; and render on the LCD terminal
     ret
 
 ; -----------------------------------------------------------------------------
diff --git a/src/term.asm b/src/term.asm
index deb6748..10cdccc 100644
--- a/src/term.asm
+++ b/src/term.asm
@@ -493,7 +493,21 @@ cursor_down:
 ; -----------------------------------------------------------------------------
 ; term_putc - A = character. Print at the cursor, advance, handle \n \r \b.
 ; -----------------------------------------------------------------------------
+; term_putc guarantees SVBK=1 so the buffer/state at $D5xx/$D6xx are the ones
+; we built, no matter which process context KPutc calls us from. The stack is
+; in non-banked WRAM ($Cxxx/$Axxx), so saving SVBK across the switch is safe.
 term_putc::
+    ld d, a
+    ld a, [rSVBK]
+    push af
+    ld a, 1
+    ld [rSVBK], a
+    ld a, d
+    call term_putc_body
+    pop af
+    ld [rSVBK], a
+    ret
+term_putc_body:
     cp 10
     jr z, .newline
     cp 13
-- 
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