Here's a little info on the CUSTOM menu:

First at $D1C5 there is a table lasting 30 bytes, with a word pointer to each of the 15
custom entries. (15 * 2 = 30)  Basically if there is a pointer present in the table, then
the custom slot has something in it.

At $D1E3 ($D1C5 + 30d) the actual custom entries begin.
They are ten bytes each.  The following is an example and explanation:

	|---This byte tells the calc how to paste the text. More later...
	|
	|					|---The remaining bytes are in the same format as the first string.
	|					|	The difference is that this string is what would appear
	|					|	next in the catalog. In this case it is "AsmComp(."
	|					|	Note that the entire string entry is not there. "AsmC"
	|					|	Also the "60" marker byte tells the ROM to use a parentheses.
	|					|
	|					|
	|			   |------------|
	60 41 73 6D 00 60 41 73 6D 43			;This is the example entry for "Asm("
	   |---------|
	   	   |
		   |---Following the first byte is the actual string, zero terminated.
		   	   Note that the parentheses isn't there. The example is "Asm("
			   That is what the first byte, which I'll call a marker byte now,
			   is used for.

The way that the entry is filled is probaly with a "ldir" instruction, where the source is
the catalog entries somewhere in the ROM and the destination is the first byte of the custom
entry and b is 10.  That is the reason for the second string which is present.

More on the "marker" bytes:

I'm guessing that the ROM routines use this byte to figure out how to paste to the screen.

Here are the marker bytes I've seen with their functions:

The example shown uses "String" as the basic custom entry, as it would be shown on home
screen

Byte			Use						Example
----			--------------------------------------		--------
00			Clean paste to home screen			"String"
10			Same as above					Same as above
20			Paste and adds a space				"String "
30			Same as above					Same as above
40			Same as 00 and 01				Same as 00 and 01
50			Paste a space the string and a space		" String "
60			Paste string with open parentheses		"String("
70			Same as above					Same as above
80			Paste Ans followed by string. No space!		"AnsString"
90			Paste Ans, a space, and string			"Ans String"
A0			Paste Ans, string, and space			"AnsString "
B0			Paste Ans, space, string, space			"Ans String "
C0			Same as 80					Same as 80
D0			Same as B0					Same as B0
E0			Paste Ans, string, and open parentheses		"AndString("
F0			Paste Ans, space, string, and open paren.	"Ans String("

I'm not sure why the marker bytes are in multiples of 16s, but there again, I'm not sure how
the ROM routines work.  This doesn't mean that patching the menu is totally impossible, yet I
haven't found out how to do it.  I've attached a program which shows that it is possible. 
It will patch your first slot to jump to the graphing menu. I think it is only possible to
jump to areas in the ROM. Haven't been able to jump to RAM, which would be further
complicated by 86's paged system.

Andres Garcia

email: xrigel@q-net.net