Configuration Guide (VT100)

This document is the single configuration reference and is split into:

• Part A: User/Operator configuration
• Part B: Admin/Developer configuration and maintenance

Table of Contents

• Part A — User / Operator
  • A1) Files you normally edit
  • A2) Setup dialogs
  • A3) VT100.txt keys (persisted)
  • A4) WLAN usage (operator level)
• Part B — Admin / Developer
  • B1) Source of truth and update checklist
  • B2) Paths and ownership
  • B3) Setup integration notes
  • B4) WLAN mode integration notes
  • B5) Planned clean mode separation
  • B6) Validation workflow after config-related changes

Part A — User / Operator

A1) Files you normally edit

• SD:/VT100.txt — terminal runtime settings.
• cmdline.txt — Circle boot options (single-line key/value arguments).
• config.txt / config64.txt — Raspberry Pi firmware display and boot options.
• SD:/wpa_supplicant.conf — WLAN credentials.

A2) Setup dialogs

• Legacy setup: open with F12.
• Modern setup: open with F11.
• Local mode toggle: F10.

Modern setup controls:

• Up / Down: select parameter
• Left / Right: change value
• Enter: save and persist to SD:/VT100.txt
• Esc: cancel changes

Modern setup save/apply behavior (current implementation):

• Applied immediately on Enter: text_color, background_color, font_selection, cursor_type, cursor_blinking, vt52_mode, smooth_scroll, buzzer_volume, switch_txrx.
• Persisted and used by runtime logic without dedicated re-init: line_ending, key_click, key_auto_repeat, wrap_around, margin_bell.
• Persisted and applied on subsystem init/reconnect/reboot: baud_rate, serial_bits, serial_parity, flow_control, repeat_delay_ms, repeat_rate_cps, log_output, log_filename, wlan_host_autostart.

Local mode (F10) behavior:

• ON: keyboard input is looped back directly to the renderer.
• OFF: keyboard input is routed to host output (UART/TCP host mode path).
• Not persisted in VT100.txt (runtime toggle only).

A3) <tt>VT100.txt</tt> keys (persisted)

Persisted by CTConfig::SaveToFile():

1. line_ending (0=LF, 1=CRLF, 2=CR)
2. baud_rate
3. serial_bits (7/8)
4. serial_parity (0=None, 1=Even, 2=Odd)
5. cursor_type (0=underline, 1=block)
6. cursor_blinking (0/1)
7. vt_test (0/1)
8. vt52_mode (0/1)
9. font_selection (1..3)
10. flow_control (0/1, software XON/XOFF)
11. text_color (0=black, 1=white, 2=amber, 3=green)
12. background_color (0..3)
13. buzzer_volume (0..100)
14. key_click (0/1)
15. key_auto_repeat (0/1)
16. smooth_scroll (0/1)
17. wrap_around (0/1)
18. repeat_delay_ms (250..1000)
19. repeat_rate_cps (2..20)
20. switch_txrx (0/1)
21. margin_bell (0/1)
22. wlan_host_autostart (0/1/2; 0=off, 1=log, 2=host)
23. log_output (0..7; 0=none, 1=screen, 2=file, 3=wlan, 4=screen+file, 5=screen+wlan, 6=file+wlan, 7=screen+file+wlan)
24. log_filename (string, max 63 chars)

A4) WLAN usage (operator level)

Endpoint: telnet <ip-or-hostname> 2323

Waiting-screen connect hints on VT100 include:

• telnet <ip-address> 2323 once concrete IP has been assigned
• telnet <hostname>.local 2323 when hostname is available
• The waiting/connect message is shown once after DHCP provides a usable IP address.

Log mode commands:

• help
• status
• echo <text>
• exit

Log mode prompt:

• >: is shown at the start of each command line in log mode.
• No prompt is inserted while host mode is active.
• Incoming log lines in log mode are separated from the prompt by spaces only (no extra CRLF inserted before a log message).
• Pressing Enter on an empty command line emits a clean newline and re-shows the prompt.

When host mode is on, keyboard TX and TCP RX are used as terminal host traffic.

Host-mode session end:

• Host mode is a dedicated raw session type.
• Session ends when the remote TCP client disconnects.

Part B — Admin / Developer

B1) Source of truth and update checklist

When adding/changing a setting, update all of:

1. CTConfig defaults table.
2. Parser validation in CTConfig.
3. Getter/setter behavior and runtime clamping.
4. Serialization in CTConfig::SaveToFile().
5. Setup dialog mapping (CTSetup) where user-editable.
6. This document.

B2) Paths and ownership

• Config persistence path: SD:/VT100.txt.
• Log output file path: SD:/<log_filename>.
• Telnet service port: 2323.

B3) Setup integration notes

• F12 raw key (0x45) triggers legacy setup behavior.
• F11 raw key (0x44) triggers modern setup behavior.
• F10 raw key (0x43) toggles runtime local mode (keyboard loopback).
• Modern setup apply path goes through CTConfig setters, then persistence via SaveToFile().
• Legacy SET-UP B maps group 1 leftmost bit (mask 0x8, VT100 “Scroll”) to smooth_scroll.
• Legacy SET-UP B maps group 2 leftmost bit (mask 0x8, VT100 “Bell”) to margin_bell.
• Legacy SET-UP B maps group 2 rightmost shown bit (mask 0x1, VT100 “Auto XON/XOFF”) to flow_control.
• Legacy SET-UP B maps group 3 second bit from left (mask 0x4, VT100 “Wraparound”) to wrap_around.
• Modern setup save path now calls kernel runtime apply for safe non-disruptive updates (renderer and HAL) to preserve stable keyboard/dialog handler routing.

B4) WLAN mode integration notes

• CTWlanLog uses one TCP endpoint with strict per-session mode separation.
• wlan_host_autostart=0 disables WLAN remote mode.
• wlan_host_autostart=1 starts a log-mode session.
• wlan_host_autostart=2 starts a raw host-mode session.

B5) Planned clean mode separation

Target model:

• Log mode: remote diagnostics only (help, status, echo, exit) with log mirroring and command prompt.
• Host mode: raw stdin/stdout host bridge only, without log/status/welcome chatter in host payload path.

Architecture-level session model, data-path gates, and lifecycle behavior are documented in docs/VT100_Architecture.md (section 8.3).

B6) Validation workflow after config-related changes

1. Build VT100.
2. Boot with a known VT100.txt.
3. Change values via modern setup (F11), save with Enter.
4. Confirm rewritten file matches expected keys/order.
5. Reboot and verify values are applied.