Ersatz-11 uses a flexible device-independent interface to allow any supported physical block device type to emulate any supported PDP-11 block device type. Each unit is defined using a simple one-line MOUNT command in the E11.INI initialization text file. Units may also be added, removed, reassigned, or displayed at any time using the pop-up E11 command prompt, without needing to stop and restart PDP-11 emulation. Bootstraps for all bootable block devices are built in to Ersatz-11's BOOT command.

Physical PC block devices:

• Disk images in container files under the host operating system.
• Raw SCSI disk drives, can interchange with real PDP-11 fixed or removable SCSI drives (including Zip, Jaz, DynaMO, etc.).
• Raw floppy drives, directly compatible with many DEC disk formats (in DOS versions only, Linux version uses PC formats);
  8" drives may be attached to single-density 5.25" FDCs using the D Bit FDADAP floppy disk adapter board.
• RAM disks in host memory, can be pre-loaded from a container file.

Emulated PDP-11 block devices:

dev name	controller types	drive types
DB:	RH11, RH70	RP04/RP05/RP06 pack drives
DC:	RC11	RS64 fixed-head disks
DD:	DL11	TU58 DECtape II
DF:/RF:	RF11	RS11 fixed-head disks
DK:/RK:	RK11D	RK02, RK05 front-loading cartridge drives
DL:	RL11[1], RLV11, RLV12	RL01, RL02 top-loading cartridge drives
DM:	RK611[2]	RK06, RK07 top-loading cartridge drives
DO:	(virtual)	Ersatz-11 interface to host file system (for DO.SYS/DOS.TSK)
DP:	RP11C	RP02, RP03 pack drives
DR:	RH11, RH70	RM02/RM03/RM05 pack drives, RM80/RP07 Winchesters
DS:	RH11, RH70	RS03/RS04 fixed-head disks
DT:	TC11	TU55/TU56 DECtape
DU:	UDA50, RQDX3, RQZX1	RA60, RA70-73, RA80-82, RA90/92, RC25, RD31-32, RD50-54, RX33/RX50 MSCP disks
DX:	RX11, RXV11	RX01 8" SS SD floppy
DY:	RX211, RXV21	RX02 8" SS DD floppy
HD:	(virtual)	Ersatz-11 hypothetical disk with simplified interface (for HD.SYS)
PD:	RXT11	RX01 8" SS SD floppy (PDT-11/150 microcomputer)

^[1] "RL211" was used as a marketing name in systems with RL02 drives, but is the identical controller to the RL11
^[2] "RK711" was used as a marketing name in systems with RK07 drives, but is the identical controller to the RK611