TABLE OF CONTENTS

potgo.resource/AllocPotBits
potgo.resource/FreePotBits
potgo.resource/WritePotgo
potgo.resource/AllocPotBits                       potgo.resource/AllocPotBits

   NAME
	AllocPotBits -- Allocate bits in the potgo register.

   SYNOPSIS
	allocated = AllocPotBits(bits)
	D0                       D0

	UWORD AllocPotBits( UWORD );

   FUNCTION
	The AllocPotBits routine allocates bits in the hardware potgo
	register that the application wishes to manipulate via
	WritePotgo.  The request may be for more than one bit.  A
	user trying to allocate bits may find that they are
	unavailable because they are already allocated, or because
	the start bit itself (bit 0) has been allocated, or if
	requesting the start bit, because input bits have been
	allocated.  A user can block itself from allocation: i.e. 
	it should FreePotgoBits the bits it has and re-AllocPotBits if
	it is trying to change an allocation involving the start bit.

   INPUTS
	bits - a description of the hardware bits that the application
		wishes to manipulate, loosely based on the register
		description itself:
	    START (bit 0) - set if you wish to use start (i.e. start
		    the proportional controller counters) with the
		    input ports you allocate (below).  You must
		    allocate all the DATxx ports you want to apply
		    START to in this same call, with the OUTxx bit
		    clear.
	    DATLX (bit 8) - set if you wish to use the port associated
		    with the left (0) controller, pin 5.
	    OUTLX (bit 9) - set if you promise to use the LX port in
		    output mode only.  The port is not set to output
		    for you at this time -- this bit set indicates
		    that you don't mind if STARTs are initiated at any
		    time by others, since ports that are enabled for
		    output are unaffected by START.
	    DATLY (bit 10) - as DATLX but for the left (0) controller,
		    pin 9.
	    OUTLY (bit 11) - as OUTLX but for LY.
	    DATRX (bit 12) - the right (1) controller, pin 5.
	    OUTRX (bit 13) - OUT for RX.
	    DATRY (bit 14) - the right (1) controller, pin 9.
	    OUTRY (bit 15) - OUT for RY.

   RESULTS
	allocated - the START and DATxx bits of those requested that
		were granted.  The OUTxx bits are don't cares.

potgo.resource/FreePotBits                         potgo.resource/FreePotBits

   NAME
	FreePotBits -- Free allocated bits in the potgo register.

   SYNOPSIS
	FreePotBits(allocated)
	            D0

	void FreePotBits( UWORD );

   FUNCTION
	The FreePotBits routine frees previously allocated bits in the
	hardware potgo register that the application had allocated via
	AllocPotBits and no longer wishes to use.  It accepts the
	return value from AllocPotBits as its argument.

potgo.resource/WritePotgo                           potgo.resource/WritePotgo

   NAME
	WritePotgo -- Write to the hardware potgo register.

   SYNOPSIS
	WritePotgo(word, mask)
	           D0    D1

	void WritePotgo( UWORD, UWORD );

   FUNCTION
	The WritePotgo routine sets and clears bits in the hardware
	potgo register.  Only those bits specified by the mask are
	affected -- it is improper to set bits in the mask that you
	have not successfully allocated.  The bits in the high byte
	are saved to be maintained when other users write to the
	potgo register.  The START bit is not saved, it is written
	only explicitly as the result of a call to this routine with
	the START bit set: other users will not restart it.

   INPUTS
	word - the data to write to the hardware potgo register and
	    save for further use, except the START bit, which is
	    not saved.
	mask - those bits in word that are to be written.  Other
	    bits may have been provided by previous calls to
	    this routine, and default to zero.


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