UNIBUS <-> PCI bridge

On Thu, 06 Aug 2009 03:59:24 +0200 Philipp Hachtmann <hachti at hachti.de> wrote: You will need an IOMMU, a "UniBus map", also. UniBus has 18 address bits, QBus 22. UniBus and QBus peripherals use bus master DMA to move data into main memory. But with only 18 / 22 Address bits these peripherals can't access the whole main memory. You would need ugly hacks like DMA bounce buffers and double memory copies to work around that. Therefore you need a programmable I/O memory management unit in the bus bridge that translates UniBus to PCI addresses. Have a look at the QBus / UniBus map / IOMMU on VAXen... Keep in mind that todays PeeCees are 64 bit... Most likely you will need some sort of slave interrupt controller. And when you do it: Make it UniBus or QBus selectable. -- tsch??, Jochen Homepage: http://www.unixag-kl.fh-kl.de/~jkunz/