// This file defines the hardware modules and interconnections of a simulated
// NED computer.
//
// Note that the simulated system is intentionally overprovisioned with respect
// to the likely hardware configuration of the real NED computer. This is
// intended to allow easy experimentation inside the simulator without
// requiring a DSL (or config file parser) for system configuration, or
// requiring frequent changes to the bootrom code.
//
// Although NED can be built (or simulated) with an arbitrary number of GBuses,
// this simulated system has two. GBus0 is intended primarily for 'compute'
// tasks and GBus1 is intended primarily for 'io' tasks.
//
// The simulated system is laid out as shown in the diagram below. Note that
// devices connected to UARTs (e.g. network, mouse, etc) are not part of NEDsim
// and are included only to document external connectivity assumed by software
// running on NED.
//
//
//                             GBus0                    GBus1
//                               v                        v
//                 +-------+     |     +------------+     |     +-------+
//      -----------|  SSB  |-----|-----|    GIMP    |-----|-----|  SSB  |----------
//      |          +-------+     |     +------------+     |     +-------+         |
//      |                        |                        |                       |
//      |                        |                        |                       |
//  +--------+     +-------+     |     +------------+     |     +-------+     +--------+
//  |        |-----| CPU 0 |-----|-----| Interrupt  |-----|-----| CPU 0 |-----|        |
//  |        |     +-------+     |     | Controller |     |     +-------+     |        |
//  | Stacks |         o         |     +------------+     |         o         | Stacks |
//  |        |         o         |                        |         o         |        |
//  |   4x   |         o         |                        |         o         |   4x   |
//  | Intrlv |     +-------+     |     +------------+     |     +-------+     | Intrlv |
//  |        |-----| CPU 7 |-----|-----|   Global   |-----|-----| CPU 7 |-----|        |
//  +--------+     +-------+     |     |   RAM 0    |     |     +-------+     +--------+
//                               |     +------------+     |
//                               |           o            |
//                 +-------+     |           o            |     +-------+
//                 | Local |-----|           o            |-----| Local |
//                 | RAM 0 |     |     +------------+     |     | RAM 0 |
//                 +-------+     |-----|   Global   |-----|     +-------+
//                     o         |     |   RAM 13   |     |         o
//                     o         |     +------------+     |         o
//                     o         |                        |         o
//                 +-------+     |                        |     +-------+
//                 | Local |-----|                        |-----| Local |
//                 | RAM 7 |     |                        |     | RAM 7 |
//                 +-------+     |                        |     +-------+
//                               |                        |
//                               |                        |
//                   +-----+     |                        |     +-----+
//                   | ROM |-----|                        |-----| ROM |
//                   +-----+     |                        |     +-----+
//                               |                        |
//                               |                        |
//  +-------+     +--------+     |                        |     +---------+     +----------+
//  | Debug |-----| UART 0 |-----|                        |-----| UART 0  |-----| Terminal |
//  +-------+     +--------+     |                        |     +---------+     +----------+
//                               |                        |
//                               |                        |
//                +--------+     |                        |     +---------+     +---------+
//                | UART 1 |-----|                        |-----| UART 1  |-----| Network |
//                +--------+     |                        |     +---------+     +---------+
//                    o          |                        |
//                    o          |                        |
//                    o          |                        |     +---------+     +----------+
//                +--------+     |                        |-----| UART 2  |-----| Keyboard |
//                | UART 3 |-----|                        |     +---------+     +----------+
//                +--------+     |                        |
//                               ^                        |
//                                                        |     +---------+     +-------+
//                                                        |-----| UART 3  |-----| Mouse |
//                                                        |     +---------+     +-------+
//                                                        |
//                                                        |
//                                                        |     +---------+
//                                                        |-----| UART 4  |
//                                                        |     +---------+
//                                                        |          o
//                                                        |          o
//                                                        |          o
//                                                        |     +---------+
//                                                        |-----| UART 15 |
//                                                        |     +---------+
//                                                        |
//                                                        |
//                                                        |     +---------+
//                                                        |-----| Block   |
//                                                        |     | Storage |
//                                                        |     | (TODO)  |
//                                                        |     +---------+
//                                                        |
//                                                        |
//                                                        |     +--------------+
//                                                        |-----| Video Output |
//                                                        |     | (TODO)       |
//                                                        |     +--------------+
//                                                        ^