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							183 lines
						
					
					
						
							7.2 KiB
						
					
					
				
			
		
		
	
	
							183 lines
						
					
					
						
							7.2 KiB
						
					
					
				IBM 4704 Keyboard
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=================
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IBM capacitive switch models:
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    6019273 Model 100 50-key (grid layout)      http://kishy.ca/?p=894
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    6019284 Model 200 62-key Alpha(60% layout)  http://kishy.ca/?p=894
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    6019303 Model 300 77-key Expanded Alpha     http://deskthority.net/photos-f62/ibm-6019303-t8502.html
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    6020218 Model 400 107-key Full key          http://kishy.ca/?p=894
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Alps switch(vintage Green) models:
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    5954339 Japanese 102-key    http://deskthority.net/post87127.html#p87127
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    6112883 Japanese 102-key    http://geekhack.org/index.php?topic=52888.msg1194489#msg1194489
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    6112884 Japanese 102-key    http://geekhack.org/index.php?topic=50437.msg1193047#msg1193047
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    6341739 Chinese 102-key     http://geekhack.org/index.php?topic=52888.msg1176566#msg1176566
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Resourse
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--------
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The IBM 4704: lots of pictures and info
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http://kishy.dyndns.org/?p=648#more-648 
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Brochure:
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http://ed-thelen.org/comp-hist/IBM-ProdAnn/4700.pdf
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IBM 4704 Keyboard Protocol
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==========================
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On powering up keyboard sends keyboard ID; A3h for 6019284(62-key), for example.
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After that the keyboard enters FC command mode and waits for parameter data from host
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so that it doesn't send any scancode until you send 'FF'(End of FC command mode).
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    Keyboard                    ID
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    -------------------------------
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    Model 100 50-key            A2h
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    Model 200 62-key            A3h
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    Model 300 77-key            A4h
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    Model 400 107-key           A5h
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    Japanese/Chinese 102-key    A6h
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Connector
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---------
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    Keyboard Plug from front
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    DSUB-9
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    -------------
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    \ N 2 3 4 5 /
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     \ N N N N /
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      ---------
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    2   GND
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    3   VCC 5V
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    4   DATA
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    5   CLOCK
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    N   No connection/No pin.
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Keyboard to Host
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----------------
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Data bits are LSB first and Pairty is odd. Clock has around 60us high and 30us low part.
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            ____       __   __   __   __   __   __   __   __   __   _______
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    Clock       \_____/  \_/  \_/  \_/  \_/  \_/  \_/  \_/  \_/  \_/
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                 ____ ____ ____ ____ ____ ____ ____ ____ ____ ____    
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    Data    ____/    X____X____X____X____X____X____X____X____X____X________
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                Start   0    1    2    3    4    5    6    7    P  Stop
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Start bit:  can be long as 300-350us.
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Inhibit:    Pull Data line down to inhibit keyboard to send.
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Timing:     Host reads bit while Clock is hi.(rising edge)
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Stop bit:   Keyboard pulls down Data line to lo after 9th clock.
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Host to Keyboard
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----------------
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Data bits are LSB first and Pairty is odd. Clock has around 60us high and 30us low part.
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            ____        __   __   __   __   __   __   __   __   __   ________
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    Clock       \______/  \_/  \_/  \_/  \_/  \_/  \_/  \_/  \_/  \_/
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                ^   ____ ____ ____ ____ ____ ____ ____ ____ ____ ____ ___
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    Data    ____|__/    X____X____X____X____X____X____X____X____X____X   \___
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                |  Start   0    1    2    3    4    5    6    7    P   Stop
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                Request by host
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Start bit:  can be long as 300-350us.
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Request:    Host pulls Clock line down to request to send a command.
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Timing:     After Request keyboard pull up Data and down Clock line to low for start bit.
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            After request host release Clock line once Data line becomes hi.
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            Host wirtes a bit while Clock is hi and Keyboard reads while low.
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Stop bit:   Host releases or pulls up Data line to hi after 9th clock and waits for keybaord pull down the line to lo.
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Scancodes
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---------
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Keyboard doesn't send Break code for all keys except for Alt by default.
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    6019284 62-key:
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    ,-----------------------------------------------------------.
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    |  `|  1|  2|  3|  4|  5|  6|  7|  8|  9|  0|  -|  =|???|BS |
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    |-----------------------------------------------------------|
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    |Tab  |  Q|  W|  E|  R|  T|  Y|  U|  I|  O|  P| ¢|  \|  PD2|
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    |-----------------------------------------------------------|
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    |Ctrl  |  A|  S|  D|  F|  G|  H|  J|  K|  L|  ;|  '| {}| PD3|
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    |-----------------------------------------------------------|
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    |Shif| <>|  Z|  X|  C|  V|  B|  N|  M|  ,|  ,|  /|???|Shift |
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    |-----------------------------------------------------------|
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    |Reset|blk|Alt  |         Space             |Alt  |blk|Enter|
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    `-----------------------------------------------------------'
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    +----------+---------------------+----------+----------+
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    |`       00|PD1     04|Caps    20|LShift  30|Reset   31|
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    |1       18|q       05|a       21|<>      3E|Rblank  41|
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    |2       19|w       06|s       22|z       32|Alt     3F|
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    |3       1A|e       13|d       23|x       33|Space   40|
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    |4       10|r       14|f       24|c       34|Alt     3F|
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    |5       11|t       15|g       25|v       35|Lblank  42|
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    |6       12|y       16|h       26|b       36|Enter   2F|
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    |7       08|u       17|j       27|n       37|          |
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    |8       09|i       01|k       28|m       38|          |
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    |9       0A|o       02|l       29|,       39|          |
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    |0       0F|p       03|;       2A|.       3A|          |
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    |-       1F|¢      1B|'       2B|/       3B|          |
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    |=       0D|\       1C|{}      2C|???     3C|          |
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    |???     0C|PD2     1D|PD3     2D|RShift  3D|          |
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    |BS      0E|          |          |          |          |
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    +----------+---------------------+----------+----------+
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    Bit7 is 'press flag' which set 1 on press and 0 on release when break code is enabled.
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NOTE: When break code is enabled the key sends scancode with setting 7th bit on press
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and without it on release. That is, '`' sends 80h on press and 00h on release.
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Keyboard command
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----------------
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Keyboard accepts these commands from host.
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        Description                             Entry point
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    -----------------------------------------------------------
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    FF  Soft Reset                              0008h
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    FE  Resend                                  00e8h
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    FD  Buzzer(emits a short beep)              00edh
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    FC  Set Key Flag                            00f6h
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    FB  Soft Reset                              0008h
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    FA  Reset                                   0000h
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Keyboard response
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-----------------
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Keyobard sends these bytes to host.
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        Description                             Entry point
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    -----------------------------------------------------------
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    FE  Overflow(key event/receive data)        00c5h, 0346h
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        Memory test error                       0224h
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    FD  Command out of bound                    00d8h
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        Key out of bound
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    7E  Read/Parity error in receive from host  00bch
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Set Key Flag command(FC)
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------------------------
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After 'Power on Reset' firmware enters this command mode and waits for data from host,
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so that you don't need to send 'FC' and it doesn't send any scancode until you send 'FF'.
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Data sent from host:
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    bit: 7   6 ... 0
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         en  |     |
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         |   `-----`--- scan code
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         `------------- enable bit(0: enable repeat, 1: enable break)
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    00-79   Enable repeat
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    80-F9   Enable break(FA-FF are used as other commands, see above.)
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    FE      Resend(011ah) no need to use
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    FF      End(0114h) exits FC command mode.
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Response from keyboard:
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    FD      Out of bound - Invalid scancode
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    --      OK - No response means that command is accepted.
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Examples:
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    To enable break code of all keys.
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    FC 80 81 ... F7 FF
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