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2011-08-17 02:28

doctorfargo

Registered: Aug 2011
Posts: 20

Hacking Questreader to work from any drive number

Hello everyone,
I'm working on updating some of my old Questwriter text adventures. Questwriter is a Text Adventure Construction Set published on Loadstar #77.

While QuestWriter is used to make the games, a smaller one-file ML program called QuestReader is used. My question is this - like most older programs, QuestReader only works on drive #8 - would it be possible for someone who is ML savvy to hack/modify the program so that it will run from any drive number?

Here's one of my old QuestWriter games - the QuestReader file is on the disk:
http://gamebase64.com/game.php?id=19357&d=18&h=0

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2011-08-19 10:56

Frantic

Registered: Mar 2003
Posts: 1648

Yeah, so that's what I thought. This is how I do it in some code somewhere btw:

	lda $ba
	and #%00001011 ;Restrict range of the current device number.
	ora #%00001000 ;Make sure it is at least $08 (i.e. in the range $08-$0b)
	sta $ba

In effect, if the current device number is between $8-$b, it will remain unaffected. If it is outside this range, it will be forced into this range. In the particular case that the current device number is set to $00 (typical when uninitialized), it will be forced to $08 instead, which is good, since $8 is the default device number in most circumstances of course.

Works good enough for my purposes and seems to be a simpler version of more or less the same thing that Krill's code does (well..). Does not solve issues like the "special cases" spelled out by Krill+J0x here, of course. Substitute "and #$b" for "and #$9" if you only want to allow device 8 and 9.

2011-08-21 08:37

Graham
Account closed

Registered: Dec 2002
Posts: 990

CMD drives also have device numbers 12-15.

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