III.3 Construction

The parts list can be found in the appendix. If you want to save the cost
of the Textool-socket, you can also use a normal 24 pin socket, but since the
two pin rows are too far apart, you will have to carefully cut the socket
along it's length, and set them to the correct distance. Or you might like
to use "MOLEX" pins instead. For IC-sockets you should only use precision
sockets. The 25 Pin Sub-D-socket (A1000) or the Sub-D-plug (other Amiga
models) is connected as follows:

  D0   = pin 2
  D1   = pin 3
  D2   = pin 4
  D3   = pin 5
  D4   = pin 6
  BUSY = pin 11
  GND  : A1000  pin 14
         A500, A2000, A3000, ...  pin 17

The supply voltage (+5V and ground (GND) you will have to get from the
Amiga's Expansion-Port or from a regulated +5V power supply. The GAL-Burner
has a maximum current consumption of about 220 mA.

The main difficulty in the construction of the GAL-burner is probably the
printed circuit board (PCB). Most likely a double sided through plated PCB
is required, so probably the best solution is to use a piece of veroboard,
and connect the relevant pins with fine hookup wire, or wire wrap wire. If
you want the whole thing to look impressive, you can use wiring guides.
The wires can be conducted via these guides, and wont go here there an
everywhere.  I have constructed my GAL-Burner and endless other projects
in this way.

If you are able to make a PCB, you can find the PostScript- or
Gerber-Files in the directory "Layout". This PCB-layout is copyright by
Thorsten Elle. Thank you Thorsten for giving me the permission to
distribute your layout together with GALer.
If you want to use the PCB-layout, please not this:
On the PCB the resistors R28 to R32 of the circuit diagram are replaced
by a resistor-array (8 * 1.8kOhm). Futhermore there is for each IC a
capacitor for anti-interferencing. These capacitors are C5 to C14 (each 100nF).

When you have built the circuit and you have connected it to the Amiga,
and the Amiga DIDN'T blow up, you can run the test program "GALerTest".
The program set various voltage levels on the Textool-socket, which you
can check with a VOM. The programming voltages are adjusted with R40-R44.
For this you can use "GALerTest".

DON'T FORGET: adjust the programming voltage with the trimpots, otherwise
              the GAL-burner will NOT FUNCTION !!!!
              (start the "GALerTest" and click through to the
               relevant test points).

If the GAL-Burner works just as the test program demands, then you can try
burning a test GAL and test it with the GAL-Checker function of GALer. If
this all works then there are no faults in the hardware. GALs of the type
GAL16V8 must be inserted in the Textool-socket, so that pin 1 of the GAL
lines up with pin 3 of the socket. With GALs of the type GAL20V8 pin 1 of
the GAL must line up with pin 1 of the socket.


Here is the pin layout of the used transistors (bottom view):


                       BC 237 and BC 327
                               _
                             -   -
                            -     -
                            -o o o-
                             -----

                             E B C





Well that's about it. Chau and have fun with the cute GALs.