Inside the Einstein: The MOS Source

The source of the Tatung Einstein's MOS, for the site's course Inside the Einstein: The MOS: the whole 8K ROM of MOS 1.2, and of MOS 1.21, as Z80 assembly for z80asm. Each file reassembles to the original ROM byte for byte, so you can read exactly what the machine runs, change it, and build a MOS of your own.

Using Them

Unzip the folder. To build the original ROM from its source:

z80asm -i mos12.asm -o mos12.i023

The course's Reading the ROM section shows how to check the result against the ROM in MAME's Einstein ROM set (the library's Einstein System ROM) and boot the Einstein with your own image.

Code is one instruction a line, with its ROM address in the comment; data is shown eight bytes a line, with the bytes as characters where they are printable. Where Crystal Research's own name for a routine is known, from Tony Brewer's facsimile of their original source, and the course explains what the routine does, the source uses it; every other label is its address.

Files in the Package

Real Hardware

Everything in the course was done in MAME. Its last appendix explains what is involved in putting a MOS into an EPROM for a real Einstein; we have not yet done that ourselves.