In other words, the MCA version of IDE (which itself is little more than an ESDI controller integrated onto the drive with an ISA bus attachment)...
Exactly, there is even a rare cable that adapted the Thinkpad 700/700C/720/720C (which were based on microchannel) DBA ESDI connection to a laptop IDE drive:
http://ibmmuseum.com/ohlandl/9552/9552_Common.html (you had to have a modified system BIOS they supplied, so it wasn't adaptable to other microchannel DBA ESDI systems)...
All told, here are the IBM systems having a DBA ESDI connection, with notes:
PS/2 Model 50Z (not the 50-021, which has a proprietary 20Mb MFM drive)
PS/2 Models N51SX and N51SLC (laptop form-factor drive)
PS/2 Model 53SLC2 (unused, as there is planar IDE)
PS/2 Model 55SX
PS/2 Model CL57SX (laptop form-factor drive)
PS/2 Model 70
PS/2 Model P70
PS/2 Model 90 (8590 has two artifact connectors for DBA ESDI drives, connections removed on 9590, unused as SCSI adapter is installed)
Thinkpad 700/700C/720/720C (laptop form-factor drive)
DBA ESDI drive sizes are 30, 40, 60, 80, 100, 120, and 160Mb, at least for the 3-1/2" form-factor drives, and capacities can be interchanged on any non-laptop DBA ESDI system. Since the drive couples to the microchannel bus, an ADF on the Reference Diskette of the system is needed to initially configure it to run the drive. The Reference Diskette also has hidden utilities to low-level format the drives.