PBP 2.42 started support for the 877A.

You can download the free version of MCS here
http://www.melabs.com/resources/win_ide.htm
but I am not sure if it works with the old versions of PBP, it should.
If you still have you receipt for PBP or remember the company you purchased it from and they still have records from that far back, the upgrade is only $25.00 US.

The new version of PBP has come a long way from 2.43. Would be worth the upgrade.