+SIO_WRITETRK = $60 ;write track (Speedy)
+SIO_READTRK = $62 ;read track (Speedy)
+
+; SIO Status Code (DSTATS)
+; Input: data direction
+; Bit #7 - W (write operation)
+; #6 - R (read operation)
+; Output: status code
+; $01 (001) -- OPERATION COMPLETE (NO ERRORS)
+; $8A (138) -- DEVICE TIMEOUT (DOESN'T RESPOND)
+; $8B (139) -- DEVICE NAK
+; $8C (140) -- SERIAL BUS INPUT FRAMING ERROR
+; $8E (142) -- SERIAL BUS DATA FRAME OVERRUN ERROR
+; $8F (143) -- SERIAL BUS DATA FRAME CHECKSUM ERROR
+; $90 (144) -- DEVICE DONE ERROR