CONSOLE(4) Minix Programmer's Manual CONSOLE(4) NAME console, keyboard, kbd, kbdaux, log, profile, vga - system console DESCRIPTION The console device driver manages a series of devices related to the main user interface: The system screen and the keyboard. These two together are named "the Console". The Screen The screen of a PC can be managed by a Monochrome Display Adapter, a Hercules card, a Color Graphics Adapter, an Enhanced Graphics Adapter, or a Video Graphics Array. To the console driver these devices are seen as a block of video memory into which characters can be written to be displayed, an I/O register that sets the video memory origin to the character that is to be displayed on the top-left position of the screen, and an I/O register that sets the position of the hardware cursor. Each character within video memory is a two-byte word. The low byte is the character code, and the high byte is the "attribute byte", a set of bits that controls the way the character is displayed, character and background colours for a colour card, or intensity/underline/reverse video for monochrome. These are the characteristics of the adapters in text mode: Adapter Usable memory Mono/Colour MDA 4K M Hercules 4K M CGA 16K C EGA 32K M or C VGA 32K M or C MDA and Hercules are the same to the console driver, because the graphics mode of the Hercules is of no use to Minix. EGA and VGA are also mostly seen as the same in text mode. An EGA adapter is either a monochrome or a colour device depending on the screen attached to it. A VGA adapter can run in either monochrome or colour (grayscale) mode depending on how the Boot Monitor has initialized it. The driver uses the video origin to avoid copying the screen contents when scrolling up or down. Instead the origin is simply moved one line. This is named "hardware scrolling", as opposed to copying memory: "software scrolling". The video origin is also used to implement several virtual consoles inside the video memory of the adapter. Each virtual console gets a segment of video memory. The driver chooses which console to display by moving the video origin. Note that an MDA or Hercules adapter can only support one console. CGA can support up to four 80x25 consoles, and EGA and VGA can have eight. It is best to configure one less console to leave some video memory free so that hardware scrolling has some space to 1 CONSOLE(4) Minix Programmer's Manual CONSOLE(4) work in. Character codes are used as indices into a display font that is stored in the adapter. The default font is the IBM character set, which is an ASCII character set in the low 128 codes, and a number of mathematical, greek, silly graphics, and accented characters in the upper 128 codes. This font is fixed in the MDA, Hercules and CGA adapters, but can be replaced by a user selected font for the EGA and VGA adapters. The Minix-vmd console driver assumes ISO Latin-1 character codes and translates them to the IBM character set as well as possible. This translation is disabled when a font is loaded. A number of control characters and escape sequences are implemented by the driver. The result is more or less compatible with the X11 terminal emulation program xterm and the VT100 terminal, and upward compatible with the standard Minix console and the ANSI standard terminal. The termcap(5) type is the same as that of xterm. Normal characters written to the console are displayed at the cursor position and the cursor is advanced one column to the right. If an entire line is filled then the cursor wraps to the first column of the next line when the next character must be displayed. The screen is scrolled up if needed to start a new line. Some characters have special effects when sent to the console. Some even have arguments in the form of comma separated decimal numbers. These numbers default to the lowest possible value when omitted. The top-left character is at position (1, 1). The following control characters and escape sequences are implemented by the console: Sequence Name Function ^@ Null Ignored (padding character) ^G Bell Produce a short tone from the speaker ^H Backspace Move the cursor back one column, wrapping from the left edge up one line to the right edge ^I Horizontal Tab Move to the next tab stop, with each tab stop at columns 1, 9, 25, etc. Wrap to the next line if necessary. ^J Line Feed Move one line down, scrolling the screen up if necessary ^K Vertical Tab Same as LF ^L Form Feed Same as LF ^M Carriage Return Move to column 1 ^N Shift Out Ignored ^O Shift In Ignored ^[ Escape Start of an escape sequence ^[D Index Same as LF ^[E Next Line Same as LF ^[M Reverse Index Move one line up, scrolling the screen down if necessary ^[c Full Reset Clear the screen, home the cursor, and 2 CONSOLE(4) Minix Programmer's Manual CONSOLE(4) reset all attributes ^[[nA Cursor Up Move the cursor up n lines ^[[nB Cursor Down Move the cursor down n lines ^[[nC Cursor Forward Move the cursor right n columns ^[[nD Cursor Backward Move the cursor left n columns ^[[m;nH Cursor Position Move the cursor to line m, column n ^[[sJ Erase in Display Clear characters as follows: s = 0: From cursor to end of screen s = 1: From start of screen to cursor s = 2: Entire screen ^[[sK Erase in Line Clear characters as follows: s = 0: From cursor to end of line s = 1: From start of line to cursor s = 2: Entire line ^[[nL Insert Lines Insert n blank lines ^[[nM Delete Lines Delete n lines ^[[n@ Insert Characters Insert n blank characters ^[[nP Delete Characters Delete n characters ^[[nm Character Attribute Set character attribute as follows: n = 0: Normal (default) attribute n = 1: Bold (mono) / Yellow (colour) n = 4: Underline (M) / Light green (C) n = 5: Blinking (M) / Magenta (C) n = 7: Reverse Video n = 30: Black foreground colour n = 31: Red n = 32: Green n = 33: Orange n = 34: Blue n = 35: Magenta n = 36: Light blue n = 37: White n = 40 - 47: Same for background colour ^[[?3l Switch console to 80 column mode and reset. A vertical line of `|' characters will appear if the console is in a mode with more than 80 columns. That line is now the right edge of the screen ^[[?3h Switch console to full width and reset. ^[]2;t^G Enable the status line and display the string t on it, any control code ends t, but ^G is the proper code The console interprets and then ignores several other escape sequences for compatibility reasons. Only the ignored control characters are listed above. The console devices implements the following ioctls to copy from or to the font memory on EGA and VGA adapters: 3 CONSOLE(4) Minix Programmer's Manual CONSOLE(4) ioctl(fd, TIOCGFON, u8_t font[256][32]); ioctl(fd, TIOCSFON, u8_t font[256][32]); Font memory consists of 256 character definitions of 32 lines per character and 8 pixels per line. The first line is the topmost line of the character. The leftmost pixel is lit if the most significant bit of a line is set, etc. How many lines are used depends on the current video mode. The 80x25 video mode used by Minix has an 8x16 character cell, 80x28 has 8x14 characters, and 132x43 has 8x8 characters. The boot variable console is used by both the Boot Monitor and the console driver to set the video mode, software scrolling on/off, and VGA screen blank timeout. See boot(8). The Keyboard The keyboard produces key codes for each key that is pressed. These keys are transformed into character codes or sequences according to the current keyboard translation table. The format of this table is described in keymap(5). The character codes can be read from the console device unless they map to special hotkeys. The hotkeys are represented by ^"name" like things in the keyboard tables. The hotkey names and the keys they are by default bound to are as follows: Name Key Function reboot CTRL-ALT-DEL Send an abort signal to process 1 (init). Init then halts the system reboot CTRL-ALT-KP-. Likewise for keypad period pdmp CTRL-F1 Process table dump mdmp CTRL-F2 Show memory map scroll CTRL-F3 Toggle software/hardware scrolling serdbug CTRL-F4 Select serial line to copy debug messages to netstat CTRL-F5 Show network statistics prio CTRL-F6 Show scheduler priority table loadav CTRL-F7 Show load averages table vmdmp CTRL-F8 Show virtual memory statistics fpemu CTRL-F9 Floating point emulation toggle (does nothing as yet) debug CTRL-F10 Toggle kernel debug flag between 0 and 1 vc0 ALT-F1 Select virtual console 0 (/dev/console) vc1 ALT-F2 Select virtual console 1 (/dev/ttyc1) vcn ALT-F(n+1) Select virtual console n (/dev/ttycn) vc- ALT-Left Select previous virtual console vc+ ALT-Right Select next virtual console st- ALT-Down Disable the status line st+ ALT-Up Enable the status line The keyboard map is set with the KIOCSMAP ioctl whose precise implementation cannot be described here for the author of this text has not looked at the new keymap code yet. 4 CONSOLE(4) Minix Programmer's Manual CONSOLE(4) VGA and keyboard devices The vga device is used by the X11 server to map the video memory into its address space. Console ouput is then sent to the log device instead, and keyboard input is no longer sent to the console but can be read as raw scan codes from the kbd device by the X11 server. The kbdaux is a serial input device for a PS/2 style mouse. Log device The log device can be used by processes to print debug messages onto the console. The console is a terminal type device, so it is taken from processes when a session leader exits. This does not happen with the log device. Messages sent to the log device are placed in a circular buffer whose contents can be read from the log device and put in a log file for instance. Several copies of the log buffer are placed into extended memory on a system crash. They are retrieved if the system is immediately rebooted. Profiling The profile device implements two ioctls, PIOCSTART, to turn on kernel profiling and make profile data available to be read from the profile device, and PIOCSTOP, to stop profiling. Precise details are currently hidden within the profile and prof_stop utilities. SEE ALSO tty(4), keymap(1), keymap(5), profile(8), boot(8). NOTES Output processing turns Line Feeds into CR LF sequences. Don't let this surprise you. Either turn off output processing or use one of the synonyms for LF. Line Feed is changed into a CR LF sequence in canonical mode. The mistreatment of the console and keyboard driver by Philip has not yet reached its limit, so one can expect some changes. BUGS Some escape sequences should provoke the console into sending identification codes back out. Processes may wait forever for these codes. Only processes that try more than the codes listed in the xterm termcap definition may be troubled by unimplemented weird features. AUTHOR Kees J. Bot (kjb@cs.vu.nl) 5