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/ EnigmA Amiga Run 1997 April / EnigmA AMIGA RUN 17 (1997)(G.R. Edizioni)(IT)[!][issue 1997-04][EAR-CD].iso / EARCD / hard / hack / KBD_Reset102.lha / KBD-Reset102_eng.txt < prev    next >
Text File  |  1996-11-25  |  7KB  |  213 lines
  1.  
  2.             KBD-Reset V1.02 (25 Nov 1996)
  3.             -----------------------------
  4.  
  5.  The problem:
  6.  
  7.    Many users have equiped their Amiga 1200 with a bigger tower-case.
  8.    Some of them may want to use an A2/3/4000 keyboard.
  9.  
  10.    This doesn't seem to make any problems, and the connection can be done
  11.    without electronic constructions. However, the reset-key-combination
  12.    (Amiga-Amiga-Ctrl) won't work.
  13.  
  14.  
  15.  The soultion:
  16.  
  17.   My circuit. This one works fine with my configuration (A1200/Eagle-Tower/
  18.   A4000 keyboard).
  19.  
  20.  
  21.  Circuit
  22.  -------
  23.  
  24.   +-----------------+
  25.   | Amiga keyboard  |
  26.   +-----------------+
  27.       |   |                KBDDATA
  28.       |   +-------------------------------+
  29.       |                                   |
  30.       |                    KBDCLK       +-------------------+
  31.       +---------------------------------| A1200 motherboard |
  32.       |                                 +-------------------+
  33.   +-----------------+      KBDRESET       |
  34.   | my circuit      |---------------------+
  35.   +-----------------+
  36.       |
  37.         / ext.
  38.        /  reset
  39.       |
  40.      -+-
  41.  
  42. (+5V power and Gnd are not mentioned here.)
  43.  
  44.  
  45.  
  46.          +5V
  47.           |
  48.          | | 100k
  49.          | |          Ge-Diode
  50.           |    |\               ____          |\           |\
  51. KBDCLK >--+----| o--+---|<|-----____----+-----| o----------| \    |\
  52.  (IN)          |/   |  ____       1k    |     |/           |  o---| o--> KBDRES
  53.                     +--____-------------+        +-----+---| /    |/     (OUT)
  54.                         33k             |        |     |   |/
  55.                                       __|__+    | |10k   / external
  56.                                  22uF _____     | |     /  reset switch
  57.                                         |        |     |
  58.                                       --+--      o   --+--
  59.                                                 +5V
  60.  
  61. part list
  62. ---------
  63.  
  64. 1* 74HCT132 (quardruple schmitt NAND gate)
  65. 1* 22uF (electolytic capicator)
  66. 1* 1K
  67. 1* 10k
  68. 1* 100K
  69. 1* 33k (Adjust)
  70. 1* Germanium Diode
  71. 1* switch (1*on), if needed
  72.  
  73. Circuit diagram 74HCT132            DIL 14 case, viewed from above
  74. ------------------------            ------------------------------
  75.  
  76.    1----|\                              +----o----+
  77.         | o---- 3                    1--|         |--14
  78.    2----|/                            --|         |--
  79.                                       --|  74HCT  |--
  80.                                       --|   132   |--
  81.    4----|\                            --|         |--
  82.         | o---- 6                     --|         |--
  83.    5----|/                           7--|         |--8
  84.                                         +---------+
  85.  
  86.    9----|\
  87.         | o---- 8
  88.   10----|/
  89.  
  90.  
  91.   12----|\
  92.         | o---- 11
  93.   13----|/
  94.  
  95.  Pin 7  = GND
  96.  Pin 14 = +5V
  97.  
  98.  
  99.  
  100. Comments
  101. --------
  102.  
  103. The 74HCT132 is a high-speed CMOS-chip. This one cannot be replaced by a
  104. 74132 or 74LS132 !
  105.  
  106. The external reset-button is optional. If it isn't needed, You may want
  107. to leave it away.
  108.  
  109. I use a germaniumdiode, to unload the electrolytic capicator as deep as possible.
  110. If this one isn't available, You can also use a 1N4148 or any other siliziumdiode.
  111. Remember that this will change the timing behaviour of the circuit.
  112.  
  113. If the circuit does not work properly (due to component tolerances), You can
  114. try to change the 33KOhm Resistor, which is marked with "ADJUST" in the          
  115. parts list, into a smaller one.
  116.  
  117. The A2000 and A3000 keyboards are the same. The only change regarding the
  118. A4000 is that its keyboard has a mini-DIN-plug instead of the standard 5-pin
  119. plug. However, all of these keyboards will work with the A1200.
  120.  
  121.  
  122. Connecting to the A1200 motherboard
  123. -----------------------------------
  124.  
  125. (The following data has been taken out of the archive "1200ExKb.lha"
  126. from Aminet-CD 5, found in directory "hard/hack").
  127.  
  128.  
  129.                                 |||||||||||
  130.                               -+-----------+-
  131.                               -|           |-
  132.                               -|           |-
  133.                               -|   8520PL  |-
  134.                               -|           |-
  135.                               -|     U7    |-
  136.                               -|           |-
  137.                               -|           |-
  138.                               -|           |-
  139.                               -|     ^     |-
  140.                               -+-----------+-
  141.                                 |||||||||||
  142.                                    ||
  143.                                    | \KBDat (solder the lead here)
  144.         |||||||||||                |
  145.       -+-----------+-               \KBClk (solder the lead here)
  146.       -|           |-
  147.       -|           |-
  148.       -| Keyboard  |---KBClk (solder here and bend pin up)              Floppy
  149.       -|  Micro.   |---KBDat (solder here and bend pin up)              Power
  150.       -|           |-
  151.       -|    U13    |-                                                   oooo
  152.       -|           |-               To                                  ||
  153.       -|           |-              front                                ||
  154.    /---|     ^     |-               of             ====>             +5v/|
  155.    |  -+-----------+-             machine                                |
  156.    |    |||||||||||                 ||     (power for the                |
  157.    |                                ||     keyboard and my           Gnd /
  158.    \_KBReset (solder the lead here) ||     circuit)
  159.                                     ||
  160.                                     \/
  161.  
  162.  
  163. Here is a connection table of some Amiga keyboards:
  164. ---------------------------------------------------
  165.  
  166. A1000: (Connector on back of keyboard itself)
  167.  
  168.         (female)                +------+
  169.                                 | |||| |        1=Gnd
  170.                                 | 1234 |        2=KBClk
  171.                                 |      |        3=KBDat
  172.                                 +-+  +-+        4=+5v
  173.                                   +  +
  174.                                    ++
  175.  
  176. A2000/3000:
  177.  
  178.         (female)                  -v-
  179.                                  /   \
  180.                                 |3   1|         1=KBClk
  181.                                 | 5 4 |         2=KBDat
  182.                                 |  2  |         3=unused
  183.                                  \___/          4=Gnd
  184.                                                 5=+5v
  185.  
  186. A4000:
  187.  
  188.        (female)
  189.                                   -v-
  190.                                  / V \
  191.                                 |6   5|         1=KBDat
  192.                                 |4   3|         2=unused
  193.                                 | 2 1 |         3=Gnd
  194.                                  \___/          4=+5v
  195.                                                 5=KBClk
  196.                                                 6=unused
  197.  
  198.  
  199.  
  200. This "hack" is mailware!
  201. ------------------------
  202.  
  203. If anyone tried to build it and succeeded, please send an E-mail to:
  204.  
  205. M.SCHULZ@FREEWAY.SHNET.ORG
  206.  
  207. Please tell me where You use the circuit. Thank You.
  208.  
  209. If You after all don't succeed, I may (no guarantee) build it for You,
  210. please contact me at the above adress. Of course, anyone with questions
  211. or comments can write to me, too.
  212.  
  213.