;
;
;
;                               IEC2IEEE
;
;                          without any warranty
;                                                                        2  C
;                                                                        5  n
;                                                                        s  t
;                                                                        u  r
;                                                                        b  n
;       IEC-BUS                              IEEE-BUS        CENTRONICS  D  c
;at    /       \                                                         -  s
;flashing      normal                         IIIIII           IIIIIIII  p  -
;IIIIIIII      IIIIII                         VVVVVV           VVVVVVVV  l  p
;VVVVVVVV      VVVVVV                                                    u  l
;                                                                        g  u
;                                                                           g
;                     (reset)        
;                   ------------------------- IFC  9 (--I<--)  Prime    16 31
;                  I       
;                  I            ----   ----                                  
;                   --<I--     I1   I I  40I                                 
;                         I    Ipb0  -  vccI--- +5V  (pin7 of C64 joystickport)
;        -----------------     I           I  '-------------------------------
;       I                      I2        39I                                  I
;       I   1 SRQin  -----I>---Ipb1     pa0I- Dt1  1 ---I<---  Data1     2  2 I
;       I                      I           I                                  I
;       I                      I3        38I                                  I
;       I   4 CLKout -----<I---Ipb2  A  pa1I- Dt2  2 ---I<---  Data2     3  3 I
;       I                      I     T     I                                  I
;       I                      I4    M   37I                                  I
;       I   4 CLKin  -----I>---Ipb3  E  pa2I- Dt3  3 ---I<---  Data3     4  4 I
;       I  ------------------' I     L     I                                  I
;       I I                    I5        36I                                  I
;       I I 5 DTAout -----<I---Ipb4  A  pa3I- Dt4  4 ---I<---  Data4     5  5 I
;       I I                    I     V     I                                  I
;       I I                    I6    R   35I                                  I
;       I I 5 DTAin  -----I>---Ipb5     pa4I- Dt5 13 ---I<---  Data5     6  6 I
;       I I                    I     A     I                                  I
;       I I                    I7    T   34I                                  I
;       I I 1 SRQout -----<I---Ipb6  M  pa5I- Dt6 14 ---I<---  Data6     7  7 I
;       I I                    I     E     I                                  I
;       I I       o#1          I8    G   33I                                  I
;CLKin  I I   (JC)o------------Ipb7  A  pa6I- Dt7 15 ---I<---  Data7     8  8 I
;       I  -------o#2      #1  I     8     I                                  I
;       I   6 RSTin -I>----o   I9    5   32I                                  I
;GND     ---------------'  o---Irst  1  pa7I- Dt8 16 ---I<---  Data8     9  9 I
;                        ,-o I I     5     I                                  I
;          --------------' #2I I10       31I                                  I
;         I              (JR)I Ipd0     icpI                                  I
;         I                  I I           I                                  I
;         I   +5V-[r=1kOhm]--  I11       30I                                  I
;         I                    Ipd1     aleI                                  I
;         I                    I           I    ^^                            I
;         I                    I12       29I    II              (+5V)         I
;         I 3 ATNin -----I>----Ipd2    oc1bI----<I--[R=1.8kOhm]---------------
;         I                    I           I                    I
;         I                    I13       28I                    I
;         I                    Ipd3     pc7I- EOI  5            I
;         I                    I           I                    I
;         I                    I14       27I                     -[+C=22uF]-
;         I                    Ipd4     pc6I- DAV  6                        I
;         I                    I           I                                I
;         I                    I15       26I                                I
;         I                    Ipd5     pc5I- NRFD 7                        I
;         I                    I           I                                I
;         I                    I16       25I                                I
;         I                    Ipd6     pc4I- NDAC 8                        I
;         I                    I           I                   #1           I  
;         I                    I17       24I              (JD) o-           I
;         I                    Ipd7     pc3I- ATN 11    -------o      (GND) I
;         I                    I           I           I     #2o--------------
;         I                    I18       23I           I                      I
;         I                    Ixtal2   pc2I---------------I<- Strobe    1  1 I
;         I                    I           I                                  I
;         I                    I19       22I            ,--I<- PaperOut 12 12 I
;         I                    Ixtal1   pc1I--------------I<-- Select   13 13 I
;         I                    I           I I       I  '--I<- Error    15 32 I
;          ------------------, I20       21I  -I<-,  I                        I
;               2 GROUND ------Ignd     pc0I------I  I--[R=10kOhm]------------I
;            (pin8 of C64  I    -----------       I   --[+C=1uF-]-------------I
;             joystickport)I                      I                           I
;                          I                       ----------- Busy     11 11 I
;                          I                                                  I
;                          I                                                 GI
;                          I                                                 NI
;                          I                --REN 17                         DI
;                          I               I                                  I
;                          I               I  GND 18           Ground   18 19 I
;                          I------------------GND  -       ----Ground    -  - I
;                          I                  GND 24      I    Ground   25 30 I
;                          I                              I                   I
;                           -------------------------------------------------- 
;
; +5V can be taken from pin 7 of C64 joystick-port
; Gnd can be taken from pin 8 of C64 joystick-port
;           
;
;
; -I>- 74LS244 ( I-I>-O)
;
;
; -<I- 7407    ( O-<I-I)
;
;
; I = input    O = output
;
;    ^^   LED 
;    II   2mA  = Error LED (not 15mA-type)
;   -<I-  type
;
;
; -I<- Diod 1N4148 (cheap universal silicon)
;
;  #1
;  o-                  usually PC2 is unconnected   
; -o o- = Jumper Debug
;  o-                  when connected to ground, then in debug mode 
;  #2                                            (debug-printing at reset
;                                                  or don't write into
;                                                  debug-buffer)
;
;                                                                     flashing)
; -o#1                 usually pb7 is unconnected (to prevent accidential 
;  o-   = Jumper Clock                                                
; -o#2                 while flashing pb7 is connected to IEC-Clock-in
;   
;
;
;
;  #1
; -o                   usually connected to IEC-Reset-in
;  o-   = Jumper Reset
; -o                   while flashing connected to ground
;  #2
;
;        IEC                            IEEE
;      __   __       _________________________________________
;     /  I I  \      \  12 11 10  9  8  7  6  5  4  3  2  1  /
;    I 5  -  1 I      \                                     /
;    I    6    I       \24 23 22 21 20 19 18 17 16 15 14 13/
;    I 4     2 I        -----------------------------------  
;     \   3   /
;      -------
;
;   1 SRQ            1 Data 1             13 Data 5
;   2 GND            2 Data 2             14 Data 6
;   3 ATN            3 Data 3             15 Data 7
;   4 CLK            4 Data 4             16 Data 8
;   5 DTA            5 End or Identify    17 Remote Enable
;   6 RST            6 Data Valid         18 Ground DAV
;                    7 Not Ready For Data 19 Ground NRFD
;                    8 No Data Accepted   20 Ground NDAC
;                    9 Interface Clear    21 Ground IFC
;                   10 Service Request    22 Ground SRQ
;                   11 Attention          23 Ground ATN
;                   12 Shield             24 Logical Ground
;
;pb7 is SCK while flashing. PB7 mustn't be connected allways to IEC-Clock-in
;because: If C64 would make IEC-Clock accidential to 0V-active when the AVR
;makes a reset, then the AVR could go into flash-mode and it could be that
;the flashROM is overwritten.
;
;74LS244 =   8 Schmitt-trigger-input-driver  not-inverting
;only necessary if one want to switch the AVR off (with switch at +5V power
;supply).
;Reason: An AVR which isn't connected with +5V power supply pulls all pins to
;0V, so the IEC bus is locked. 
;isn't necessary if one never switches off the AVR
;
;7407 =   6 open-collector-busdriver-chip   not-inverting
;only necessary when more than three additional serial devices (additional to
;C64 and AVR) are connected to the IEC-bus.
;Reason: All serial devices have got a 1kOhm pullup-resistor, so it should be
;neccessary that it needs 5mA to pull a wire of the IEC-bus to 0V-active.
;The AVR-output can make 20mA. This should be enough for 1 C64 and 3 devices.
;isn't necessary if there are only  1 - 3 serial devices connected.
;
;All diods and all things at pc2 - pc0 are only necessary if you want to use
;the AVR as printerinterface and if you want to connect a Centronics-printer.
;The printer is also important to print analyse-bytes to find software-bugs.
;
;The 8 diods at the parralel-port pa7-pa0 are only necessary if one want to
;switch off the Centronics-printer.
;Reason: A switched-off printer pulls all lines to 0V, so the parallel
;IEEE-bus is locked.
;isn't necessary if the Centronics-printer is allways switched on.
;The 5 diods at the printer-control-port (pc2-pc0) are allways necessary.
;The connection to prime of Centronics-printer can be made or not just how
;one wants. If it is made then there is allways a printer-reset when you make
;a C64-reset. 
;
;If you just want an interface of IEC- to IEEE-bus then it's possible to use
;an AVR and the cable with plugs only without any additionla chips.
;
;There is no crystal neccessary, the AVR uses the internal 8MHz oscylator.
;
;The switch S is for printing of the analyse-bytes. Switch it on; make a reset;
;switch it off, so the AVR-RAM is printed.
;
;Make a stable +5V power supply.
;
;The Reset pullup resitor isn't allways necessary; you can try without
;
; This program is free software; you can redistribute it and/or modify it
; under the terms of the GNU General Public License as published by
; the Free Software Foundation; either version 2, or (at your option)
; any later version.
;
; Use of this software in other projects is allowed and encouraged; however,
; the author would like to be notified of any such projects.
;
;   Jochen Adler   Near Letter Quantity  
;   Haeldestr.9  D74912 Kirchardt  Germany
;   NLQ@gmx.de  www.nlq.de
;
;
;
;                    without any warranty - own risk