                        *********************
                        **      A F R      **
                        *********************
                        
                         Amiga Floppy Reader

                                v 1.0f

                        (c) 1997, Marco Veneri


WHAT IS AFR ?
-------------

        AFR is a project (program + schematic circuit) to connect Amiga
        external floppy to the PC parallel port and to create a .adf
        image for the great UAE emulator (thanks to all the people working
        around it).
        All you need is a PC with a BIDIRECTIONAL parallel port and
        some time to build the circuit.
        Note: on new mother board LPT can be configured as SPP, ECP and EPP.
                If the program is not able to read data at all, try
                changing this parameter in your machine bios setup.
                (On my machine AFR works only with SPP and EPP, but not
                with ECP).
                Moreover be aware of USB host controller: on some machine
                (like mine) it conflicts with the LPT port, so you have
                to disable it.
        I would be pleased to know if someone else build this circuit and
        to know how it works (my prototype is working quite fine).
        Obviously Amiga custom circuit are more flexible with old and
        almost rotten disks (some kind of real oversampling PLL is used
        inside of them), but even with my circuit you should be able to
        read almost all of your old disks. 
        Some note about disk import speed:

                P200 MMX Intel             : 46 sec.
                P100 Cyrix (no ext. cache) : 82 !!!!

        For any question or suggestion please contact me by e-mail !

AFR USE
-------

        The program is really very simple and little words are needed to get
        it working.
        When the program starts it asks you about your LPT port address. Once
        selected you enter the main program mask. Here all you have to do
        is to insert the name of the disk image you are going to read in,
        then the floppy will start reading.
        If you don't want to read any more disk just press enter when you
        are asked about the file name.
        While the program is reading a disk you can press ESC key to get
        back to the filename mask.
        Please do not blame me for not having included a user interface but
        I spend all the time I had (August 1997) to develope the circuit and
        to write MFM decoding code (it was not quite simple because of the
        lack of infos about some technical questions).
        
        
COPYRIGHT
---------

        Really simple: I do not want to make money with this project but,
        obviously, no one else must ! I put all the stuff in the public
        domain because I think that someone could be interested in the code
        or in the schematic. Moreover if someone will make some upgrade or
        modify to my source or schematic I hope he will let me know
        something about it. I also hope that if someone makes any further
        version or project based on my AFR he will report at least a
        greeting to me !
        Finally, if someone makes money with AFR and start living at
        Honolulu..... Fuck off!!

        
THE CIRCUIT
-----------

        The circuit is made with 5 generic low-cost ICs and, once built,
        needs only to be trimmed for optimal performance.Note: trimmer R4
        must be a multiturn !

        The ICs are:

        1 - TLC555 : every ones knows this IC but be carefull: in my circuit
                        it is used in an original way, infact it emulates a
                        really stupid 'PLL' ( this is not quite exact ).
                        It is the heart of the circuit since it must recover
                        the bit clock of the data stream flowing out of the
                        drive. This IC can NOT be replaced with a normal
                        (non CMOS) 555.Also TS555 is working fine.
			I've no infos about 7555 up to now.
        2 - 74LS374: this is an 8-bit buffer used to latch data. With
                        only a little effort this IC could probably be
                        eliminated at all.If someone make such a modify please
                        let me know !
        3 - CD4040 : It is used to generate two clocks: the first is the latch
                        pulse for the 374 and the clear pulse for the shift
                        register. The second clock is a trigger signal for
                        the PC LPT and is polled by the software to read byte.
        4 - 74LS14 : some inverters. Two of them are used to extract the
                        front edge from the incoming bitstream. This pulse
                        is used to reset the oscillator.
        5 - 74LS164: shift register

        Once you have biult your board you must make just one operation.
        Connect all up, insert a disk (Amiga format) and launch the AFR
        program.
        Start reading the disk image. Rotate the multiturn trimmer for
        faster and best disk reading. You can use the SECTOR-METER to
        find the optimal position.

	All the circuit needs an external power supply with +5 and +12.
	A small PC power supply would be quite good!

PCB NOTES:
----------

	The PCB layout I've included in this version of AFR is a single face
	PCB, so anyone could make it with just a little effort. On the
	component side of the PCB you must also put some 'bridge' useing some
	short stub of wire (see top.bmp file).In the lower-left side of the PCB
	you'll find the 4 pads to connect the external power supply (2 grounds, 
	+12 and +5). In the middle there is the P2 connector: use this holes to
	wire the DB23 female floppy connector (to do this you must use 12 short
	stubs of wire).
	On the right side is P1 connector. Again use short stubs of wire to
	connect the DB25 male PARALLEL connector.

TODO:
-----

        I collected some suggestion and hint for future expansion of AFR
        porject. I don't know if I'll have time to implement them, anyway
        here they are:

        - Win 95 GUI
	- Connecting a normal 1.44 PC floppy disk.

ATTENTION:
----------

          I assume no responsibility for the consequences of use of such
          program and circuit, nor for any problem or hardware damage which
          may result from its use.

TEST SUGGESTION
---------------

	Here are some tests to do after you have build your AFR circuit:
	
	- Before connecting AFR circuit to PC or floppy or to the power supply
		check the following connections:
		- pin 23 of DB23 connector should be connected to +12V supply
		- pin 12 of the DB23 connector should be connected to +5V supply
		- pin 15 of DB23 connector should be connected to pin 12 of the
			DB25 connector
		- pin 3, 4, 5, 6, 7 of DB23 connector should be connected
			to power GND
		- pin 19, 20, 21, 22, 23, 24, 25 of DB25 connector should be
			connected to power GND
	If this is all OK then you can proceed useing the AFR circuit.

E-Mail:   marco_veneri@hotmail.com
-------

                                              Good work  to the
                                              UAE project team!

