Apparently, I don't understand what I thought I knew
about what this macro does.

	It is a very simple macro included as an example in the
gpasm assembler.

movwf1          MACRO   arg             ;diddle regs in RAM bank 1
    movwf       (arg^0x80)              ;invert MSB
    endm

	I had written some code to build the option register 1
bit at a time by setting and clearing bits in a RAM register and
then writing the byte to OPTION_REG which is in Bank 1 so I
wrote:

	 BCF STATUS, RP0 ; Bank0
	 CLRF option_reg_init ;Know what we are turning on by
;first turning off everything.
	BCF option_reg_init, PSA ;TMR0 gets the prescaler.
	 BSF option_reg_init, PS2
	 BSF option_reg_init, PS1
	 BSF option_reg_init, PS0 ;1/256
	BCF option_reg_init, T0CS ;TMR0 to clock
	BCF option_reg_init, INTEDG ;int on drop of GP2 pin 5
	MOVFW option_reg_init ;Get ready to set OPTION_REG
    movwf1      OPTION_REG

I thought this macro would invert the bank select bit and write
to 0x81 but instead, it wrote to TMR0 at address 1 which is what
you would get if you tried to write to OPTION_REG without
setting Bank 1 in status.

	If I set Bank 1 in status, then this macro does invert
the bit and a write accesses a register in Bank 0 so it works
that way, just not from Bank 0, trying to write to Bank 1.

	The main question boils down to proper use of the
resources in gpasm. Can you actually write 1 bit at a time to W,
using the provided names of the bits from the PIC's include file
somewhat the same way that config works?

	__CONFIG _INTRC_OSC_NOCLKOUT & _WDT_OFF & _PWRTE_OFF & _MCLRE_ON &  _BOREN=
_ON & _BODEN_ON & _CP_OFF & _CPD_OFF

	This is not the first PIC code I've written, but I had
run in to some issues that raised these questions. I like to try
to write code that one can still read years later and
truly understand what was supposed to happen at the time.

	Thanks very much.
Martin McCormick WB5AGZ
--=20
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