RX02 Emulator v1.96

Minor update to allow compatibility to use the latest released SDfat library v2.2.0 code. Conditional compilation tests added to support the v2.0.6/v2.0.7 versus the v2.1.0/v2.2.0 releases as there were minor variable name changes in some method calls. No other changes.

Update: Fully regression tested on my PDP-11/44 RX211 and passes DEC ZRXFB0 functional test and DEC ZRXDC0 performance exerciser. Boots and runs RT11 v5.7 successfully. Changed status from pre-release to release.