Roland MT-32 Stuff
Dr. Scott M. Baker Page
Vintage MIDI: Roland MT-32, Roland SC-55, HardMPU, and an Xi 8088
PS2-TTL Serial Adapter for RC2014 and MIDI
Roland MT-32 Service Notes 3rd ed. [Oct 88]
Roland MT-32 Service Notes 1st ed. 
Ultimate Roland MT-32 Tutorial [Phil's Computer Lab]
Serial Port Controller, HITR Page 235 physical [Oct 1990]
Serial controller Types
• Type 1 appears identical to the serial portion of the IBM PC AT Serial/Parallel Adapter.
• Type 2 incorporates all functions of Type 1 and also supports FIFO mode.
• Type 3 incorporates all functions of Type 2 and provides DMA mode.
• Type 4 incorporates all functions of Type 3 and provides additional I/O addresses.
Note: Some systems using the Type 2 controller do not support the FIFO mode. For information about individual systems refer to the system-specific technical reference manuals.
NOTE: Do not exceed 19.2K Baud with Type 1 and Type 2 Serial Controllers. In short, older PS/2s can't reach the serial Baud rate needed [parallel is something else].
31,250 baud directly supported on Types 3 and 4 using the High Frequency Mode, divisor of 22 [decimal]. Percentage of error Difference between Desired and Actual 0.538