Z80 CPU
               ,----------------.___.----------------.
  <--    A11  1| io[19] 57                 55 io[18] |40 A10    -->
  <--    A12  2| io[20] 58                 54 io[17] |39 A9     -->
  <--    A13  3| io[21] 59                 53 io[16] |38 A8     -->
  <--    A14  4| io[22] 60                 51 io[15] |37 A7     -->
  <--    A15  5| io[23] 61                 50 io[14] |36 A6     -->
  -->    CLK  6|  XCLK  22                 48 io[13] |35 A5     -->
  <->     D4  7| io[24] 62                 42 io[ 8] |34 A4     -->
  <->     D3  8| io[25]  2                 43 io[ 9] |33 A3     -->
  <->     D5  9| io[26]  3                 44 io[10] |32 A2     -->
  <->     D6 10| io[27]  4                 46 io[12] |31 A1     -->
     VCC_5V0 11|               Caravel     45 io[11] |30 A0     -->
  <->     D2 12| io[28]  5       pins                |29 GND
  <->     D7 13| io[29]  6                 41 io[ 7] |28 /RFSH  -->
  <->     D0 14| io[31]  8                 33 io[ 2] |27 /M1    -->
  <->     D1 15| io[30]  7                 21 io[ 0] |26 /RESET <--
  -->   /INT 16| io[33] 12                 34 io[37] |25 /BUSRQ <--
  -->   /NMI 17| io[32] 11                 37 io[ 6] |24 /WAIT  <--
  <--  /HALT 18| io[34] 31                 32 io[ 1] |23 /BUSAK -->
  <--  /MREQ 19| io[35] 13                 36 io[ 5] |22 /WR    -->
  <--  /IORQ 20| io[36] 14                 35 io[ 4] |21 /RD    -->
               `-------------------------------------'

    GND     29 (Z80) --- vss*               56, 52, 38, 39, 29, 23, 20, 10, 1
    VCC_5V0 11 (Z80) --- vddio              64, 17
    VCC_1V8    (LDO) --- vccd, vccd1, vccd2 63, 49, 18