Re: Stepping through Rocky's Boots (to possibly P8 it)

[Steve Nickolas <usotsuki@buric.co>]

Almost got all the information I need.

There is a file on the disk, CLR FINDSLOT BOOT.O, which loads at $0800.

I believe this is the routine used to select the file that ROCKY HELLO.O 
loads.  The challenge is, how does it do this?  I did a quick disassembly 
but it doesn't make a lot of sense.  (The code appears to be slightly 
obfuscated.)

0800: 4C 03 08 A9 00 8D F2 03 A9 08 8D F3 03 49 A5 8D [L..)..r.)..s.I%.]
0810: F4 03 A9 00 8D 00 60 20 63 08 01 60 00 60 FF BF [t.)...` c..`.`.?]
0820: A9 00 8D 00 09 20 63 08 01 09 00 09 FC 1F A9 00 [).... c.....|.).]
0830: 8D F4 03 8D F3 03 8D F2 03 A9 00 85 00 A9 C8 85 [.t..s..r.)...)H.]
0840: 01 A0 07 C6 01 A5 01 C9 C0 F0 F2 8D F8 07 B1 00 [. .F.%.I@pr.x.1.]
0850: D9 5B 08 D0 EC 88 88 10 F5 6C 00 00 20 FF 00 FF [Y[.Pl...ul.. ...]
0860: 03 FF 3C 68 85 00 68 85 01 20 B1 08 85 02 20 B1 [..<h..h.. 1... 1]
0870: 08 85 03 20 B1 08 85 04 20 B1 08 85 05 20 B1 08 [... 1... 1... 1.]
0880: 85 06 20 B1 08 85 07 A0 00 A5 05 C5 07 D0 04 A5 [.. 1... .%.E.P.%]
0890: 04 C5 06 F0 02 B0 13 B1 04 91 02 E6 04 D0 02 E6 [.E.p.0.1...f.P.f]
08A0: 05 E6 02 D0 02 E6 03 4C 89 08 A5 01 48 A5 00 48 [.f.P.f.L..%.H%.H]
08B0: 60 E6 00 D0 02 E6 01 A0 00 B1 00 60             [`f.P.f. .1.`    ]

I think my ProDOS replacement will be somewhat larger than this.  I only 
have 256 bytes to put the code in, so I have to be careful.  (The main 
loader can be larger than 256 bytes.)

Most likely, my loader will use the usual BB00 buffer, and programs which 
need the BF page will need to find their own place for it and mark it, and 
the replacement for this file will copy it back.

-uso.