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qmk_firmware/converter/ibm4704_usb/ibm4704.txt

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IBM 4704 Keyboard
=================
IBM capacitive switch models:
6019273 Model 100 50-key (grid layout) http://kishy.ca/?p=894
6019284 Model 200 62-key Alpha(60% layout) http://kishy.ca/?p=894
6019303 Model 300 77-key Expanded Alpha http://deskthority.net/photos-f62/ibm-6019303-t8502.html
6020218 Model 400 107-key Full key http://kishy.ca/?p=894
Alps switch(vintage Green) models:
5954339 Japanese 102-key http://deskthority.net/post87127.html#p87127
6112883 Japanese 102-key http://geekhack.org/index.php?topic=52888.msg1194489#msg1194489
6112884 Japanese 102-key http://geekhack.org/index.php?topic=50437.msg1193047#msg1193047
6341739 Chinese 102-key http://geekhack.org/index.php?topic=52888.msg1176566#msg1176566
Resourse
--------
The IBM 4704: lots of pictures and info
http://kishy.dyndns.org/?p=648#more-648
Brochure:
http://ed-thelen.org/comp-hist/IBM-ProdAnn/4700.pdf
IBM 4704 Keyboard Protocol
==========================
On powering up keyboard sends keyboard ID; A3h for 6019284(62-key), for example.
After that the keyboard enters FC command mode and waits for parameter data from host
so that it doesn't send any scancode until you send 'FF'(End of FC command mode).
Keyboard ID
-------------------------------
Model 100 50-key A2h
Model 200 62-key A3h
Model 300 77-key A4h
Model 400 107-key A5h
Japanese/Chinese 102-key A6h
Connector
---------
Keyboard Plug from front
DSUB-9
-------------
\ N 2 3 4 5 /
\ N N N N /
---------
2 GND
3 VCC 5V
4 DATA
5 CLOCK
N No connection/No pin.
Keyboard to Host
----------------
Data bits are LSB first and Pairty is odd. Clock has around 60us high and 30us low part.
____ __ __ __ __ __ __ __ __ __ _______
Clock \_____/ \_/ \_/ \_/ \_/ \_/ \_/ \_/ \_/ \_/
____ ____ ____ ____ ____ ____ ____ ____ ____ ____
Data ____/ X____X____X____X____X____X____X____X____X____X________
Start 0 1 2 3 4 5 6 7 P Stop
Start bit: can be long as 300-350us.
Inhibit: Pull Data line down to inhibit keyboard to send.
Timing: Host reads bit while Clock is hi.(rising edge)
Stop bit: Keyboard pulls down Data line to lo after 9th clock.
Host to Keyboard
----------------
Data bits are LSB first and Pairty is odd. Clock has around 60us high and 30us low part.
____ __ __ __ __ __ __ __ __ __ ________
Clock \______/ \_/ \_/ \_/ \_/ \_/ \_/ \_/ \_/ \_/
^ ____ ____ ____ ____ ____ ____ ____ ____ ____ ____ ___
Data ____|__/ X____X____X____X____X____X____X____X____X____X \___
| Start 0 1 2 3 4 5 6 7 P Stop
Request by host
Start bit: can be long as 300-350us.
Request: Host pulls Clock line down to request to send a command.
Timing: After Request keyboard pull up Data and down Clock line to low for start bit.
After request host release Clock line once Data line becomes hi.
Host wirtes a bit while Clock is hi and Keyboard reads while low.
Stop bit: Host releases or pulls up Data line to hi after 9th clock and waits for keybaord pull down the line to lo.
Scancodes
---------
Keyboard doesn't send Break code for all keys except for Alt by default.
6019284 62-key:
,-----------------------------------------------------------.
| `| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| -| =|???|BS |
|-----------------------------------------------------------|
|Tab | Q| W| E| R| T| Y| U| I| O| P| ￠| \| PD2|
|-----------------------------------------------------------|
|Ctrl | A| S| D| F| G| H| J| K| L| ;| '| {}| PD3|
|-----------------------------------------------------------|
|Shif| <>| Z| X| C| V| B| N| M| ,| ,| /|???|Shift |
|-----------------------------------------------------------|
|Reset|blk|Alt | Space |Alt |blk|Enter|
`-----------------------------------------------------------'
+----------+---------------------+----------+----------+
|` 00|PD1 04|Caps 20|LShift 30|Reset 31|
|1 18|q 05|a 21|<> 3E|Rblank 41|
|2 19|w 06|s 22|z 32|Alt 3F|
|3 1A|e 13|d 23|x 33|Space 40|
|4 10|r 14|f 24|c 34|Alt 3F|
|5 11|t 15|g 25|v 35|Lblank 42|
|6 12|y 16|h 26|b 36|Enter 2F|
|7 08|u 17|j 27|n 37| |
|8 09|i 01|k 28|m 38| |
|9 0A|o 02|l 29|, 39| |
|0 0F|p 03|; 2A|. 3A| |
|- 1F|￠ 1B|' 2B|/ 3B| |
|= 0D|\ 1C|{} 2C|??? 3C| |
|??? 0C|PD2 1D|PD3 2D|RShift 3D| |
|BS 0E| | | | |
+----------+---------------------+----------+----------+
Bit7 is 'press flag' which set 1 on press and 0 on release when break code is enabled.
NOTE: When break code is enabled the key sends scancode with setting 7th bit on press
and without it on release. That is, '`' sends 80h on press and 00h on release.
Keyboard command
----------------
Keyboard accepts these commands from host.
Description Entry point
-----------------------------------------------------------
FF Soft Reset 0008h
FE Resend 00e8h
FD Buzzer(emits a short beep) 00edh
FC Set Key Flag 00f6h
FB Soft Reset 0008h
FA Reset 0000h
Keyboard response
-----------------
Keyobard sends these bytes to host.
Description Entry point
-----------------------------------------------------------
FE Overflow(key event/receive data) 00c5h, 0346h
Memory test error 0224h
FD Command out of bound 00d8h
Key out of bound
7E Read/Parity error in receive from host 00bch
Set Key Flag command(FC)
------------------------
After 'Power on Reset' firmware enters this command mode and waits for data from host,
so that you don't need to send 'FC' and it doesn't send any scancode until you send 'FF'.
Data sent from host:
bit: 7 6 ... 0
en | |
| `-----`--- scan code
`------------- enable bit(0: enable repeat, 1: enable break)
00-77 Enable repeat(78-7F: invalid scancode)
80-F7 Enable break(F8-FF: invalid scancode)
FE Resend(011ah) no need to use
FF End(0114h) exits FC command mode.
Response from keyboard:
FD Out of bound - Invalid scancode
Examples:
To enable break code of all keys.
FC 80 81 ... F7 FF
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