Pro-Log was a major manufacturer of STD cards. The cards here arrived in a collection of almost 100 STD cards (thanks yet again, Andrew). I guessed by their appearance and dates that they probably went together, and later found that they were all related to a Pro-Log System 20.
The card cage is not the original unit but works fine. The system boots a ROM version of MS-DOS 3.2. The ROM card also has 128k of RAM for a RAM disk with provision for battery backup.
The 8088 processor card has 128k and with two additional 256k RAM cards the total system memory is 640k.
The system also includes a CGA card, floppy disk controller card, printer card, and a prototyping card.
The system includes a solid state disk drive card with two drives (nominally H: and I:) each of which can hold 4x 64kB EPROM or static RAM.
The H: drive has three EPROMs programmed with MS-DOS 3.2. Imaging the ROMs and concatenating the binaries produces an image file just like those used with a Gotek or a Greaseweazle.
An operator’s manual was and utilities disk were recently uncovered from the same source as the cards. It would have been better at the start, but it confirms a lot of things and hints that there was once a SCSI card available. It also lists compatible 7000 series Pro-Log I/O cards.