The S-MPU-AT is partially hardware intelligent: it relies on detection of intelligent MPU-401 requests to become MPU-IPC-T compatible (intelligent).
http://media.rolandus.com/manuals/S-MPU-AT_OM.pdf
The S-MPU-IIAT relies on a DOS TSR to become intelligent emulated.
http://media.rolandus.com/manuals/S-MPUII_OM.pdf
Both products were designed for Windows and not DOS back in the day.
I owned both but found the MPU-401, MPU-401AT, MPU-IPC, MPU-IPC-T, SCC-1 and LAPC-I to be better alternatives. As well as select clones such as the Midiman MM-401 and Music Quest PC MIDI Cards (8 & 16BIT).
The S-MPU-AT BOB pops up on eBay from time to time and is usually pretty cheap.
