The 68000 Node Board will be designed and prototyped by EC. MS will take over manufacturing, testing, and service after the final testing of prototypes. The anticipated specifications of the 68000 node board will be:
68000 CPU
256K Dynamic RAM with Parity (40 x 4164)
4K/8K/16K PROM (2 x [2716, 2732, 2764])
2 Async RS-232 ports (header pin connectors)
1 Parallel I/O port (header pin connector)
9512 Math processor (if it fits)
S-100 bus I/O interface
The node board will look like two I/O ports to the S-100 bus master. The base port address will be settable with a DIP switch. There will be a data port and a control port. Data written to the data port by port by the 68000 may be read by the S-100 bus master. The data port is bidirectional without restriction. The control port may be used by the S-100 bus master to:
Hardware reset the 68000
Interrupt the 68000
Set a status bit the 68000 can read
Clear interrupt
Clear status bit
The control port may be used by the 68000 to:
Interrupt the S-100 master
Set a status bit the S-100 master can read
Clear interrupt
Clear status bit
In addition the control port may be read to determine the value of the status bit. This allows either interrupt or non-interrupt synchronisation of data transfer between the host and the node board.