Change of diskdefs for more formats

config_files/cpm/diskdefs

@@ -1939,3 +1939,22 @@ diskdef jet80.8
   os 3
 end
 
+diskdef cpm3
+  seclen 128
+  tracks 77
+  sectrk 26
+  blocksize 1024
+  maxdir 128
+  boottrk 3
+  os 3
+end
+diskdef metric8
+  seclen 256       # Confirmed 256-byte sectors
+  tracks 154       # 77 tracks × 2 sides
+  sectrk 26        # 26 sectors/track
+  blocksize 2048   # 8 sectors/block (256×8=2048)
+  maxdir 256       # Increased directory entries
+  boottrk 4        # You confirmed boot tracks 0-3
+  sides 2          # Double-sided
+  dirblks 4        # Directory spans 4 blocks (8KB)
+end