ES-1841 (transliterated name), 'ec1841' driver.
A clone of PC XT, in different form factor -- 7-slot passive backplane, no ISA connectors; bus signals are the same. Can be expanded just like XT, using a pair of transmitter/receiver cards. Either MDA or CGA video.
- No memory on CPU board; memory boards are divided into banks, failing banks can be disabled.
- Always ships with a MFM hard drive; relevant routines are included in main BIOS.
- Custom mouse controller.
- Custom dual-port serial controller.
- Custom LAN controller (might be Token Ring).
- Character generator is changeable (INT 10H, AH=11H)
- Keyboard has extra keys to switch the layout.
Apparently there was a speech synthesis card, but not much is known about it. Probably used this TMS5100 clone: http://www.155la3.ru/k1803.htm
Quick reference manual and BIOS listing: http://zx.pk.ru/attachment.php?attachmentid=35804&d=1338407315
Technical manual haven't been found yet.
Software samples -- Alpha-DOS (localized MS-DOS clone; plain DOS works too), TPS (diagnostics), demo disk: http://zx.pk.ru/attachment.php?attachmentid=35911&d=1338919944
M86 (CP/M-86) was also distributed with the machine, no good copies were found yet.
MESS status -- POST fails memory test (probably due to unemulated memory controller) and hard disk test (because HDC is not configured in the driver); these can be ignored. Boots into DOS and is somewhat usable (Shift keys don't work, and you have to use MESS debugger to switch to Latin layout). Keyboard ROM or MCU is not dumped yet. Tests from the TPS disk mostly fail, too. The demo disk works, though :-) If you run it, answer 'l' at first prompt (it asks if you have a color monitor).
Debugger trick is 'do b@418 = 2'.
POST failure (press F1 here)
Alpha-DOS -- MODE, LABEL, and CHKDSK commands
Demo disk, intro
Demo disk, intro
Demo disk, graphics demo