What are the positives and negatives of first-past-the-post and additional member electoral systems?

Define the terms:First past the post system: The MP for each constituency is from the party which got the most votes in that particular constituency. Additional member system: There is one tier of single member district representatives. There is then another tier of so called 'additional members' who are elected to make the overall results more proportional?FPTP: Positives: Stable governments, though this argument has been eroded by experience of coalition government. Clear member-constituency link. Negatives: Lack of proportionality, wasted votes, safe seats.AMS: Positives: Increased proportionality. Improved voter choice - allowing a choice over a range of parties. Negatives: Lack of stable governments, for example years in which Holyrood (Scottish Parliament) was in No Overall Control. Link discussion to other electoral systems, for example PR (Proportional Representation) to improve understanding of whole topic.