Atari Jaguar Video-Games Programming and Development
Uploading to BJL Modified Jaguar
|First of all make sure that you have a fully working BJL
system. I am using an old laptop running DOS and Windows to develop on, and
using the DOS loader to upload to the BJL. The normal DOS loader supports
both 4-bit and 8-bit file transfers, and understands how to upload .COF files
as well as plain binaries. Badcoder will provide .COF files normally as they
work on BJL and Alpine.
| If you have the most recent version of
the BJL ROM fitted to your modified Jaguar then you will have a number of
built-in games, stored in ROM, and requiring no loading time, a great advantage
The BJL screen offers both 4 bit and 8 bit upload options, but you do not
need to do anything from here as the DOS uploader program can send the transfer
The M68000 registers are shown too, very useful if a program in development
crashes as all M68000 exceptions call this screen.
usage: loader [-s skipbytes] [-w wiat] [-b baseaddr] [-p lptbase] [-n] [-8] <filename>
skipbytes is # byrtes in header to skip. default = 0
baseaddr is addr to upload to. default = 0x00004000
lptbase specifies base addr of LPT port default = 0x378
wait - counter between longs. default = 1
-n => don't send switch-command
-8 => use 8Bit transmission <4Bit is default>
c:\badcoder\> lo badcode2.cof
badcode2.cof is 327367 bytes long
COFF-Header found ...
start is $4000
transmit-lenght is 327199
|Useful tip- the BJL has no menu item or key-press to run
a program from a particular address. You can do this from the DOS loader,
however, by running lo with the name of a file which does not exist. Due
to a bug, presumably, it does not check for the file first, and sends the
'run' instruction to the BJL anyway. Thus, you can start the program just
by typing something like 'lo run' where run does not exist, and it will start
the program at the default address of $4000.
| While the binary is loading you do not
see anything particularly special, the screen flickers in a coloured band
over the BJL loader text message, which itself tells you whether the upload
is the default 4 bit or 8 bit, and shows the address as it loads, but this
is not easy to see as the band flickers so quickly. If the screen goes black
for a short time during loading this may not mean failure, often with Underground
binaries there are some uncompressed data areas which cause it.