The slots now gracing the innards of the machines were provided later, so that add-on boards for printers, monitors and internal modems could easily be connected.

The CPU and support chips are merely one add-on board.

Real-time clocks, memory expansion, and coprocessors were popular, and some companies even managed to combine all three into a single add-on board.

The add-on board would display up to 4000 characters on a TV or monitor.

The cards also had ports for special add-on boards, such as the Rainbow Runner, which could add various functionality.

I.B.M. will release specifications that will allow companies to make add-on boards for its machines.

But it also raised the price of admission for loyal customers, because MCA won't accept the customers' old add-on boards or floppy disks.

It is an add-on board for PCs.

In reality, the SLOW function was done by an add-on board that was factory-mounted over the main board.

For example, the internal slot structure of the new PS models will not accept classic add-on boards.