ScuzzBlog: Diaries April 2020
Entry 19th April 2020: Post 01: Amiga - Writing your own BOOTBLOCK.
Amiga - Writing your own BOOTBLOCK.
I am not going to pretend I know the first thing about BOOTBLOCKS,
so when I show here how to write a BOOTBLACK, I literally am
just quoting the contents of a useful program I found.
So what exactly is a BOOTBLOCK .... [ Quote and not my words ].
The bootblock L I N K : From vignettes/amigaDiskFiles
The bootblock is actually the first two blocks on an Amiga disk:
amigaBlock(adf.example, 0) and amigaBlock(adf.example, 1). When the
Commodore Amiga system boots, it will first load these blocks in
memory and uses this to check what type of disk it is. Any executable
code on this block will be run when the bootblock checksum is valid.
When the system is already booted when the disk is insert, the
bootblock will just be used to determine what type of disk it
represents.
And so by writing code to this region gives direct control over how
the disk is perceived.
L I N K : Check this out from Wiki
The fun for Amiga users in the day was utilising the first 1024
Byte Sector 0 which is always read first. The first sectors and
or BOOTBLOCK was one way crackers got their messages ahead of
games and sadly also how the pesky virus was transmitted to
Amiga users. If you have ever run a Virus checker it will advise
when a BOOTBLOCK is none standard and alert you to it. Crunchers
also identified BOOTBLOCK status when they unarchived files.
The whole BOOTBLOCK magic has been exploited to the full with any
number of demos coded to work in this area. Crackers used the
customised BOOTBLOCK to boast about their skills in breaking into
games. When you open a cracked game it will be the first thing
you see.
There is plenty on the web about BOOTBLOCK demos. Also there is
a whole art based around ANSI that could fill pages of blogs here
so go do some digging. Like I say I am no expert.
So what did I use ? The software is called BootWriter which I
unpacked from a AUI coverdisk for June 1996. Fortunately it can be
found on Aminet plus a load more others.
L I N K : BootWriter
L I N K : Aminet query for bootblock
In no time at all I had created a disk with a fancy intro and topped
it off with one of my Aguilera disk icons. All very entertaining,
especially when you use other folks boot code.
I have dabbled with the Action Replay side expansions pilfering mods
and images, though not a whole game I have to say. All that I did
I deleted and used only for the blog. Seriously. The Synchro Express
was also featured in a blog along with the Cyclone dongle and
software. I include the links below.
I can well imagine bedroom coders having great fun putting together
their own disks and sharing them at various group meets and parties.
It really isn't that hard in truth. Whilst gadgets like the Action
Replay and Synchro Express advised against nicking copyrighted
material they did make the process a cake walk in truth.
One final comment was that I suggested in a recent forum post that
I would look into a cracked game to try and see why it was hanging
during play. The game was Sword of Honour. Why wasn't I surprised
to see the game cracker promoting him/herself in the BOOTBLOCK.
Trouble was that any broken code was never going to be fixed by
the cracker and so the problem just got spread through the community
like a games virus. And that was the risk you took.
Me I tend to only use proper disks, basically cus I like the art
work, manuals, guides and real disks. Just feels so much better.
L I N K S
Synchro Express II | Action Replay
Cyclone and XCOPY
Amiga - Writing your own BOOTBLOCK.
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