great room-slow progress

I haven't posted in a week, progress was very slow. first, I had to work all week, so time was limited to late afternoon early evening. Then, I had some holes to patch in the 1/2" subfloor, which took time. Then I had to deal with tearout of the old floor in the hallway. Here has been the BIG snag--dealing with the doorways! If I just tear out at will, I run a very high risk of having the particle board chip out under the floors I am keeping. SO the search went on to find a way to score the doorways so when I tear out, it will tear out square. I tried a chisel-no good. I bought a rotozip tool, burned out a bit in 3 feet. After looking at some on-line video, I am going to try a different attachment and see what happens. If I can get this accomplished, then I can put down some more plywood and get to laying more floor.