[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Re: ISA BUS Master

> I want to build a ISA card witch has to read 8 Kbyte from the Video Text
> Memory. This Card should be run under any PCI Boards with an ISA Bridge.
> Does every ISA Bridge Support "ISA BUS MASTER " ?
> When my Cards became a Bus Master, must i take over the Refresh Signal
> every 15 Ás , or is this Signal on the ISA-BUS is only a relict from the
> former 128Kbyte RAM Card`s in the 80th s ?
> ANDI@ius.gun.de

all ISA busses by definition support ISA dma which includes ISA bus mastering.
I'd not plan on holding the ISA bus for an entire 8K transfer however!  Do
about 8-16 xfers in a burst, release the bus and rearbitrate it.  that will
alleviate you from worrying about refresh or anything else, as well as
forstalling any interrupt latency issues.