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PDP-11 (or 8) worthwhile without disk drives?


Veteran Member
Aug 23, 2010
Silicon Valley USA
There are several options for both PDP-11 and PDP-8 that don't use legacy spinning magnetic media.

PDP-11 TU58EM TU-58 emulator. Requires a Windows/Linux PC or equivalent to run the emulator server code (see https://github.com/AK6DN/tu58em) and an extra serial port on the PDP-11 as the hardware interface. Capable of running XXDP diagnostic images (useful for debug, not much else) but also large enough for a minimal RT-11 system. Search this forum for TU58EM, should find lots of activity. I use TU58EM on my PDP-11/34 system with an extra DL11-W, and on my PDP-11/44 system, using the integrated second serial port, principally for running XXDP and diagnostics. I have run RT-11 but it is not my preferred option for this. XXDP disk images available here: http://www.ak6dn.com/PDP-11/TU58/

PDP-11 RX02 Emulator. A hardware/software solution to emulate legacy RX01/2 disk drives. A bit of hardware (custom shield) and an Arduino processor board connect to a legacy RX11/RX211/RXV11/RXV21 floppy drive interface and replace the physical RX01/02 drive hardware. Runs any operating system that supports the RX02, like XXDP, RT11, RSX, etc. See https://github.com/AK6DN/rx02_emulator for more info, and also search this forum for 'rx01 rx02 emulator'. Lots of info. I have an RX211 interface in my PDP-11/44 and run either XXDP diagnostics from it, or RT-11-based programs. XXDP disk images available here: http://www.ak6dn.com/PDP-11/RX02/

PDP-11 SCSI. Very affordable for QBUS, not so much for UNIBUS, with real SCSI disk drives, or the SCSI2SD (google it) SCSI drive emulator using SD cards. Runs most (all?) operating systems that have SCSI interfaces and appropriate O/S drivers (ie, MSCP DU device). XXDP, RT11, RSX, RSTS, 2.11BSD unix all run. I have EMULEX UC17/UC18 UNIBUS SCSI cards in both my PDP-11/34 and PDP-11/44 and use them to run RT11, XXDP, RSTS, and 2.11BSD on my 11/44; RT11 and XXDP on my 11/34. Both with legacy 1GB SCSI disk drives, and now with SCSI2SD emulator boards replacing the disk drives with MicroSD card storage.

PDP-8 OS8DiskServer (see https://github.com/drovak/os8diskserver). Similar to how TU58EM works, except on a PDP-8. Requires a dedicated extra serial port interface card in your PDP-8, plus a dedicated Windows/Linux PC to run the server software. Capable of running the OS8 operating system with a custom setup (ie, new driver).

PDP-8 RX02 Emulator - Same hardware setup as PDP-11 RX02 emulator, above, except on a PDP-8. Requires an RX8E (RX28) floppy interface card in your PDP-8, otherwise the same external hardware as listed above for the PDP-11. Runs OS8 RX01/2 legacy floppy images transparently (ie, faithfully emulates a legacy RX01/2 disk drive). I have a floppy interface board in my PDP-8m and now use the RX02 emulator (in place of real RX02 drives) to run OS8v3D operating system images.