RE: Update
Date: 2008-02-28 08:21:32

Hallo William,

> This looks to be a syntax check, with the table being masks
> to use with the check.

That was very clear to me. But have a look at this piece of code:

L_C254	lda	IMAGE
		ldx	INSTRU
		and	TblSyntax-8,X	; combine with checkbyte
		bne	L_C260		; faulty syntax, ->

My understanding from this bit of code is that X may vary from 8 to 12
because the table goes from $FEAD to and including $FEB1. But now have a
look at this code:

		cpx	#$09		; commandnumber < 9 ?
		bcc	L_C184		; yes ->

		jsr	ChkSyntax	; test for R, S or N

L_C184	ldx	INSTRU		; X = commandnumber

This code says to skip the ChkSyntax routine if X is smaller then 9.
This include the value 8. From $FE89 you'll find the table with the
characters that represent the various commands in plain ASCII. 

		ldx	#$0B

L_C16A	lda	TblCommands,X	; compare commands
		cmp	CHAR		;   with char
		beq	L_C17A		; found, ->

You see that the code starts with value 11, which represents New, and
can go down to 0, Validate. This means that 8 = Copy. So the question
is: why is Copy excluded from the Syntax check?

> in the structure table, STRUCT ($FEA5+)

The table starts at $FEAD, not at $FEA5. The first eight values simply
don't exist. The value you'll find at that place are the hi-bytes of the
address of the various commands. 

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