I’ve had a few Emails recently about checking out the source for RISC OS from the ROOL CVS.
Here are the commands I used on a new Ubuntu installation to checkout the OMAP4Dev branch.

sudo apt-get install cvs
export CVSROOT=:pserver:anonymous:@riscosopen.org:/home/rool/cvsroot
cvs login
(if prompted for a password, just press return, no password is required)
cvs co -d bin castle/Admin/bin
chmod 0777 -R bin
sudo ln -s /usr/bin/perl /bin/perl
./bin/checkout OMAP4Dev

To checkout different branches of the CVS, simply change the last line, the current available options are;
BCM2835 – Raspberry Pi (Stable)
BCM2835Dev – Raspberry Pi (Dev)
BCM2835Pico – Raspberry Pi (Pico Dev)
Disc – Harddisc components (Stable)
DiscDev – Harddisc components (Dev)
iMx6Dev – ARMX6 (Dev)
IOMDHAL – Risc PC/A7000 (Stable)
IOMDHALDev – Risc PC/A700 (Dev)
OMAP3 – Beagleboard (Stable)
OMAP3Dev – Beagleboard (Dev)
OMAP4 – Pandaboard (Stable)
OMAP4Dev – Pandaboard (Dev)
OMAP5Dev – OMAP5 (Dev)
PlingSystem – !System components for pre RISC OS 5
Titanium – Titanium (Stable)
TitaniumDev – Titanium (Dev)
Tungsten – Iyonix (Stable)
TungstenDev – Iyonix (Dev)