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Lecture 20 - March 19, 2003
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AGENDA:
0 Admin
1 P5 questions?
2 Return exam #1
3 Ch 3.9: terminals
4 Ch 3.10: the system task

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0 - ADMIN
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Startout Q: 

Due by start of class
* RI #6
Due tonight
* P5

Due Friday
* Exam #2

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1 - P5 QUESTIONS?
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Any questions?

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2 - RETURN EXAM #1
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Return and discuss briefly

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3 - CH 3.9: TERMINALS
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HARDWARE TYPES
* memory-mapped terminals
  - video RAM, video controller, scan lines, text vs.
    video modes, IBM PC keyboard scan codes, detection
    of key combinations (ALT, CTRL, SHIFT, combo.)
* RS-232 terminals
  - escape sequences, demo capturing codes, check
    /etc/termcap for VT100 entry
* X terminals
  - X-stations vs. emulation software
  - bit-mapped, gray scale vs. color
  - X server & clients
  - communicate by sending messages between clients
    & server

TERMINAL SOFTWARE - INPUT
"How would you like you input processed: well, medium,
  or rare?"
- raw (noncanonical), cooked (canonical), & inbetween

What is the life of a keystroke from the time you press
  the keyboard until you see the echo back on your
  display?

- gets to driver, may undergo keyboard mapping for
  different keyboard layouts, chars may get buffered up
  and processed for metachars (erase, etc. -- show
  stty -all), echoing back to screen
- interesting problems: tab handling, <ENTER> vs. 
  CR + LF
special keys: fig 3-33 p. 244

control functions: tcgetattr, tcsetattr, or via IOCTL
- fig 3-34 p. 246
- settings: CR->NL, 7- vs. 8-bit, echoing, line vs.
  character at a time I/O

TERMINAL SOFTWARE - OUTPUT
* RS-232: buffer output & feed as hardware does the 
  baby bird thing (asking for more input).
* memory-mapped: write to video RAM as become available
  - scrolling video memory: move address of buffer base 
    in a special register instead of copying all data
  - controller wraps around to beginning of buffer
  - cursor register
* ANSI sequence: fig 3-36 p. 249

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4 - CH 3.10: THE SYSTEM TASK
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Questions?

COS 421 - Lecture Notes #20		SPRING 2003	
COS421-lect-2003-03-19.doc	Page 2	Printed 19.03.03