Momentus

From Inertial Computing
Jump to: navigation, search

Based on the Motorola MPC860 5V tolerant PowerQUICC CPU, running at either 33, 50, 66, or 80MHz.

The Zorro II 16-Bit/7.14 MHz bus operates in practice at around 28.56 Mbit/s, or 3.56 MBytes/s. The Zorro II bus uses 4 clocks per 16-Bit of data transferred.

The Freescale/Motorola MPC860 is perfectly suited to being a co-processor for the Amiga for a slew of practical reasons:

  • 5V TTL logic level tolerance
  • Ability to communicate directly with the 68K CPU/memory bus
  • Ability to bridge to PCI using Tundra QScale II which costs $35

The MPC860 will communicate with the Amiga via two distinct channels:

  • "In-band" via a Zorro (II, not III) to SPI bridge. The advantage of this is that the MPC860 can communicate via SPI in multi-master mode, which is similar/mappable to the bus-mastering that is already employed on the Zorro bus. If this proves to not be feasable, slave mode can be considered instead. In 16-bit SPI mode, the MPC860's SPI interface performance *at 25MHz* is 3.125Mbit/sec, or about a third of a megabyte per second.
  • "Out-of-band" via the MPC860's External Bus Interface (see Chapter 13 of the MPC860 PowerQUICC User Manual)

The development systems (There are three) are Wind River MPC860 systems.

The Tundra Semiconductor CA91L862A QSpan II PCI Host Bridge is $30 from Future Electronics in single quantities


  • Could we bridge to the Intel FW82801BA southbridge? They are around 425 actual BGA pads and cost as low as $6 new. Supports HD Audio, SATA, ATA, all sorts of good shit.

PCBs made by Futurelec's PCB Manufacturing service perhaps

Also see Momentus Parts List