converter/ibm4704_usb/ibm4704.txt

   1 4704 Keyboard
   2 =============
   3 Keyboard Models:
   4     Model 100 6019273 50-key (grid layout)
   5     Model 200 6019284 62-key Alpha(60% layout)
   6     Model 300 6019303 77-key Expanded Alpha
   7     Model 400 6020218 107-key Full key
   8
   9 Resourse
  10 --------
  11 The IBM 4704: lots of pictures and info
  12 http://kishy.dyndns.org/?p=648#more-648
  13
  14 Brochure:
  15 http://ed-thelen.org/comp-hist/IBM-ProdAnn/4700.pdf
  16
  17
  18
  19 4704 Keyboard Protocol
  20 ======================
  21 On powering up the keyboard sends keyboard id; A3h for 6019284(62-key), for example.
  22 After that firmware enters FC command mode and waits for parameter data from host
  23 so that it doesn't send any scancode until you send 'FF'(End of FC command).
  24
  25
  26 Connector
  27 ---------
  28     Keyboard Plug from front
  29
  30     DSUB-9
  31     -------------
  32     \ N 2 3 4 5 /
  33      \ N N N N /
  34       ---------
  35     2   GND
  36     3   VCC 5V
  37     4   DATA
  38     5   CLOCK
  39     N   No connection/No pin.
  40
  41
  42 Keyboard to Host
  43 ----------------
  44 Data bits are LSB first and Pairty is odd. Clock has around 60us high and 30us low part.
  45
  46             ____      __   __   __   __   __   __   __   __   __   ________
  47     Clock       \____/  \_/  \_/  \_/  \_/  \_/  \_/  \_/  \_/  \_/
  48                  ____ ____ ____ ____ ____ ____ ____ ____ ____ ____
  49     Data    ____/    X____X____X____X____X____X____X____X____X____X________
  50                 Start   0    1    2    3    4    5    6    7    P  Stop
  51
  52 Start bit:  can be long as 300-350us.
  53 Inhibit:    Pull Data line down to inhibit keyboard to send.
  54 Timing:     Host reads bit while Clock is hi.
  55 Stop bit:   Keyboard pulls down Data line to lo after 9th clock.
  56
  57
  58 Host to Keyboard
  59 ----------------
  60 Data bits are LSB first and Pairty is odd. Clock has around 60us high and 30us low part.
  61
  62             ____        __   __   __   __   __   __   __   __   __   ________
  63     Clock       \______/  \_/  \_/  \_/  \_/  \_/  \_/  \_/  \_/  \_/
  64                 ^   ____ ____ ____ ____ ____ ____ ____ ____ ____ ____ ___
  65     Data    ____|__/    X____X____X____X____X____X____X____X____X____X   \___
  66                 |  Start   0    1    2    3    4    5    6    7    P   Stop
  67                 Request by host
  68
  69 Start bit:  can be long as 300-350us.
  70 Request:    Host pulls Clock line down to request to send a command.
  71 Timing:     After Request keyboard pull up Data and down Clock line to low for start bit.
  72             After request host release Clock line once Data line becomes hi.
  73             Host wirtes a bit while Clock is hi and Keyboard reads while low.
  74 Stop bit:   Host releases or pulls up Data line to hi after 9th clock and waits for keybaord pull down the line to lo.
  75
  76
  77 Scancodes
  78 ---------
  79 Keyboard doesn't send Break code for all keys except for Alt by default.
  80
  81     6019284 62-key:
  82     ,-----------------------------------------------------------.
  83     |  `|  1|  2|  3|  4|  5|  6|  7|  8|  9|  0|  -|  =|???|BS |
  84     |-----------------------------------------------------------|
  85     |Tab  |  Q|  W|  E|  R|  T|  Y|  U|  I|  O|  P| ￠|  \|  PD2|
  86     |-----------------------------------------------------------|
  87     |Ctrl  |  A|  S|  D|  F|  G|  H|  J|  K|  L|  ;|  '| {}| PD3|
  88     |-----------------------------------------------------------|
  89     |Shif| <>|  Z|  X|  C|  V|  B|  N|  M|  ,|  ,|  /|???|Shift |
  90     |-----------------------------------------------------------|
  91     |Reset|blk|Alt  |         Space             |Alt  |blk|Enter|
  92     `-----------------------------------------------------------'
  93     +----------+---------------------+----------+----------+
  94     |`       00|PD1     04|Caps    20|LShift  30|Reset   31|
  95     |1       18|q       05|a       21|<>      3E|Rblank  41|
  96     |2       19|w       06|s       22|z       32|Alt     3F|
  97     |3       1A|e       13|d       23|x       33|Space   40|
  98     |4       10|r       14|f       24|c       34|Alt     3F|
  99     |5       11|t       15|g       25|v       35|Lblank  42|
 100     |6       12|y       16|h       26|b       36|Enter   2F|
 101     |7       08|u       17|j       27|n       37|          |
 102     |8       09|i       01|k       28|m       38|          |
 103     |9       0A|o       02|l       29|,       39|          |
 104     |0       0F|p       03|;       2A|.       3A|          |
 105     |-       1F|￠      1B|'       2B|/       3B|          |
 106     |=       0D|\       1C|{}      2C|???     3C|          |
 107     |???     0C|PD2     1D|PD3     2D|RShift  3D|          |
 108     |BS      0E|          |          |          |          |
 109     +----------+---------------------+----------+----------+
 110     Bit7 is 'press flag' which set 1 on press and 0 on release when break code is enabled.
 111
 112 NOTE: When break code is enabled the key sends scancode with setting 7th bit on press
 113 and without it on release. That is, '`' sends 80h on press and 00h on release.
 114
 115
 116 keyboard command
 117 ----------------
 118     FF  Soft Reset(0008h)
 119     FE  Resend(00e8h)
 120     FD  Buzzer stop?(00edh)
 121     FC  Set Key flag(00f6h)
 122     FB  Soft Reset(0008h)
 123     FA  Reset(0000h)
 124
 125
 126 Keyboard response
 127 -----------------
 128     FF  Not exist. [Outgoing buffer cannot have FFh(00h in fact)]
 129     FE  Overflow(key event/receive data)        at 00c5h, 0346h
 130     FE  Memory test error                       at 0224h
 131     FD  Command out of bound                    at 00d8h
 132         Key out of bound
 133     7E  Read/Parity error in receive from host  at 00bch
 134
 135
 136 Set Key flag command(FC)
 137 ------------------------
 138 After 'Power on Reset' firmware enters this command mode and waits for data from host,
 139 so that you don't need to send 'FC' and it doesn't send any scancode until you send 'FF'.
 140
 141 Data sent from host:
 142
 143     bit: 7   6 ... 0
 144          en  |     |
 145          |   `-----`--- scan code
 146          `------------- enable bit(0: enable repeat, 1: enable break)
 147
 148     00-77   Enable repeat(78-7F: invalid scancode)
 149     80-F7   Enable break(F8-FF: invalid scancode)
 150     FE      Resend(011ah) no need to use
 151     FF      End(0114h) exits FC command mode.
 152
 153 Response from keyboard:
 154     FD      Out of bound - Invalid scancode
 155
 156 Examples:
 157     To enable break code of all keys.
 158
 159     FC 80 81 ... F7 FF
 160