sharing 1TB western digital space

How can I share the drive space of a 1TB Western Digital external HDbetween my macbook and an old pc

One way would be to reformat the WD drive to FAT-32 which allows read - write access for both your PC and Mac. Note that FAT-32 is limited to a single file size of around 4 GB.

Fat 32

Fat 32 How does that affect things please?

Both computers can read and write to the hard drive (as long as you're not trying to connect it to both machines simultaneously). The drawback to FAT 32 is that no single file can be larger than 4GB

Great, many thanks for your time

Few files other than movies are bigger than 4GB, so you can just read that as "no movies."

OK well noted, thank you.