According to this scan of a Roland document (http://www.symphoniae.com/synth/Roland/MPU401 … F-IPC_Cable.pdf) the cable is a direct pass through of all pins with the exception of pin 13 and 25 which are described as " straight across and also crossed wired". I only have half of an original cable but looking inside I don't see any cross wiring and looking at the circuit of the IPC and the MPU-401 and it looks like tho use pins are ground pins. I just tested my MPU-401 and MIF-IPC with a 25 pin straight through serial cable and it works perfectly 😀