Epson 4000 - Manual (Page 141)

Write-protect
To protect the data on a diskette from being changed by setting
the write-protect switch on a 3.5-inch diskette or by placing a
write-protect tab over the notch on a 5.25-inch diskette. You
cannot change data on a write-protected diskette.
ZIf socket
Zero Insertion Force. The type of socket on your system board
that holds the microprocessor. With this type of socket, it is
easy to remove and install processor chips.
ZIP chip
Zig-zag Inline Package. The type of optional video memory
chip you can install on the system board. On this type of chip,
the pins alternate in a zig-zag pattern rather than symetrically.
Glossary 9