This computer is what is the ZX-80 to the ZX-Spectrum, but for the Oric 1. Tangerine developped this computer before they became Oric and produced the Oric-1.
It was mainly sold in kit, without the complete keyboard shown in the photo, but with a little hexadecimal keyboard.
The unextended Microtan 65 couldn't use Basic (Basic65) due to its RAM limitation (1kb), so only machine-code was usable.
Te 1kb ROM contained TANBUG, a monitor which allowed to enter machine code programs. But with the unextended Microtan65, there was no way to save your work (not tape facility), so you had to re-type your program each time you switched-on the computer !