While the likes of Lee Harper have put pen to paper, six players are yet to decide whether to remain with The Cobblers or move on.
Paul Trollope, Rob Ullathorne, Eric Sabin, Chris Hargreaves, Derek Asamoah and Steve Morison have until the end of June to sign their deals before the offers are withdrawn.
"Lee Harper signed last week and we're still talking to the other players," said Calderwood to the club's official website.
"We are hopeful that we will conclude a deal with Eric Sabin in the next week or so, and we are keeping our fingers crossed that by the end of June a number of the other out-of-contract players will sign.
"We have already received a boost with the news of Lee signing and Scott McGleish coming to join us and if we can tie up a number of other deals we will be in pretty good shape for the start of pre-season.
"The deals offered to Paul Trollope, Rob Ullathorne, Eric Sabin, Chris Hargreaves, Derek Asamoah and Steve Morison are on the table until the end of June."
