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TRIPUTER

I bought in September 2016 an FPGA development board called Cyclone V GX Starter Kit from Terasic (see Figure 1). It costs 179 US$ and uses a 28-nm FPGA with six 3.125 Gbps transceiver channels from Altera. The board offers a 32-bit wide LPDDR2 DRAM memory with 512 Mbytes capacity. This device has a very high bandwidth for many applications. In addition the board has a HDMI output, an audio device, an SD card interface, many LEDs and switches and some expansion connectors.

The plan is to realize with this board a "multiple computer" system. The name TRIPUTER is an indication of how many systems will be integrated. The first one will be the PC532 running NetBSD. The second one will be the Ceres-3 using Oberon. Currently the last one will be the BBC computer with the 32016 Second Processor.

Using a commercial board for this purpose is the best choice. Nevertheless the board is not ideal. For example it lacks an Ethernet port and a real time clock. But it is cheap and the used FPGA is a modern one which will be available for many years. The missing features can be added through the expansion connectors. I will develop the necessary hardware for it too.

The three computers to be integrated are very different from a software point of view. Having them available in one system should be an exciting experience. The FPGA of the board is big enough to hold the required hardware.

Fig. 1. The initial configuration of the Cyclone V GX Starter Kit is presenting a photo of itself on the screen

Of course such a complex system is not build over night. It will take a while to realize it. To get an overview about the different tasks and their status I have made a milestone plan.

Milestone 1 : PC632M is running with an SD card.

Description: the PC632M is using an IDE hard disk drive as mass storage. This requires a translation in hardware from SCSI operation to IDE operation because NetBSD 1.5.3 for the PC532 is using a SCSI driver. Using an IDE drive with the Cyclone V GX Starter Kit is not an useful option. It is better to support SD cards. Therefore the translation hardware has to be modified.

There might be a problem with the SD card endurance if NetBSD is writing intensivly to mass storage. A solution can be a SATA interface. The required hardware (high-speed transceivers) is provided by the FPGA. But it is a lot of effort to develop a SATA interface...

Status: work in progress.

Milestone 2 : PERI board is ready to use.

Description: the PERI board is a little PCB which uses the 40-pin connector at the left side of the Cyclone V GX Starter Kit in Figure 1. It will contain a real-time-clock (RTC), a standard format SD card connector, a PS2 connector for keyboard and mouse and a true serial interface. The serial interface on board the Starter Kit is an USB version. This will be ok if the TRIPUTER is used with a PC as a terminal. TRIPUTER V1.0 will support this mode of operation. The true serial interface is for people who like or have to work with a traditional RS232 interface.

The plan is to enable TRIPUTER V1.0 to work without the PERI board. The great disadvantage is then the missing RTC for NetBSD. The later versions of TRIPUTER will require the PERI board because of the use of mouse and keyboard.

Status: to be done.

Milestone 3 : M32632 is connected to LPDDR2 DRAM.

Description: the very high speed of the DRAM makes it necessary to modify the interfaces of the M32632 caches. The result will be the version 3 of the M32632. The goal is to save one cpu clock cycle for every DRAM access and two clock cycles between two DRAM accesses, for example first access is for data and second access is for instruction. The reference system is the PC632M.

Status: to be done.

Milestone 4 : TRIPUTER system V1.0 is available.

Description: version 1.0 of TRIPUTER will contain the PC532 system. The reasons for choosing the PC532 as the first system are that I know it very well and there is some interest from other people. TRIPUTER will use some boot software written by me to manage the different guest systems.

Status: to be done.

This chapter was last modified on 6 November 2016. Go to Top