All ROM files you can find inside PMD 85 Emulator ZIP package (Rom folder). See Download section on our site.
If you have PMD 85-2A, use monit2B.rom (rather than monit2A.rom). It is 4kB file that you need split into four 1kB files and Write them into 1kB EPROMs (2708, К573РФ1).
On the following site you can find whole schematic of the PMD 85-2A (other models PMD 85 too). http://www.sapi.cz/pmd-85/pmd85-2a.php
You can try to replace old 1kB ROMs by new 4kB/8kB ROM.
ROM begins at 8000h and ends ar 8FFFh. Keep in mind that ROM is mirrored from 0A000h to 0AFFFh.