Last week a beginner told me he couldn’t run SYNTAX programs. I was very surprised, since I test every program we print myself. He tried to use 8K ROM programs on his 4K ROM. He didn’t understand the difference between the 2 ROMs, or what ROMs or RAMs are.
ROM stands for read only memory. Your ZX80 or MicroAce has a 4K ROM memory chip (see binary number story for discussion of 4K). This chip holds instructions designed by the manufacturer for the computer. You cannot alter the ROM–it’s read only. The new 8K ROM will contain 4K more instructions for the computer, so it will have greater capabilities.
You also have 1K or 2K RAM, or random access memory, depending on your machine. RAM stores the data and instructions you type in. The machine needs 40 bytes to store system variables, but the rest is yours to fill with programs.