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'[PIC]Definition of CALL?'
1996\04\13@215359 by Xaq

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I have a question about the definition of the CALL instruction(on the '74 if
that makes any difference).  I have read in the MICROCHIP data book that the
instruction "CALL K" would be valid as long as K is not zero and is less
than 2048.

In the Parallax documentation, it says that:
" The ninth bit of the program counter will be cleared to 0. Therefore,
calls are only allowed to the first half of any 512-word page, although the
CALL instruction can be anywhere."

Which is correct?  There is no mention of clearing the ninth bit in the
MICROCHIP manual.

If the Parallax manual is correct, than I have another question.  How can
one find out where there program's instructions are positioned in memory.  I
looked at the .LST file created by the Parallax assembler, but I was not
sure if the hex numbers numbers (the second column) where the actual
position of each instruction.  It does not appear so because because it
lists all of the ram declarations (example: ram_space ds 1) as actual
instructions.  I assumed that the ram declarations where strictly for the
assembler and were not actual code.



Thanks in advance

Zach Radding

PS I have been getting weird anomalies in my programs, but I just re-arrange
my functions being called and then everything works.  I want to know why.

1996\04\14@004809 by Clyde Smith-Stubbs

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Xaq <spam_OUTxaqTakeThisOuTspamINDIRECT.COM> wrote:

> In the Parallax documentation, it says that:
>  " The ninth bit of the program counter will be cleared to 0. Therefore,
> calls are only allowed to the first half of any 512-word page, although the
> CALL instruction can be anywhere."
>
> Which is correct?  There is no mention of clearing the ninth bit in the
> MICROCHIP manual.

This clearing of the bit applies only to the 16C5x chips, not the 16C74 or
any other 16C6x or 7x chips.

Clyde

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