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From: Jonathan Kirwan on 3 Feb 2005 21:07 On 3 Feb 2005 15:12:33 -0800, aiiadict(a)gmail.com wrote: >Modern computer with PCI only, need to plug in an ISA card. The southbridge or PCI-ISA bridge chip can only exist with "side-band" channels to the main chipset. There is only one of these possible, and then only if the rest of the chipset supports the southbridge concept. The side-band channels do not exist as signals on the PCI bus, so I don't believe that it would be possible to do a PCI board that provides full ISA -- more particularly, support for ISA DMA. You might be able to get by with some specialized FPGA or ASIC for the purposes of a reduced ISA feature set connecting to the PCI (no DMA and with subtractive decoding for the ISA address space.) I haven't heard of such a thing, though. Jon
From: Keith Williams on 4 Feb 2005 09:36 In article <1107472353.146712.193780(a)c13g2000cwb.googlegroups.com>, aiiadict(a)gmail.com says... > Keith wrote: > > >>They have PCI<->ISA brifges that work > >>quite well. There are also PCI<->ISA cards > > Can you let me know where I can get a PCI to > ISA card? > > Modern computer with PCI only, need to plug > in an ISA card. I've run across such things occasionally. Do a web search on '"PCI to ISA" + card' or some such. A quick search found these (rather expensive) external chassis PCI to ISA extenders and I've seen others (no idea how well any work): http://www.accesio.com/go.cgi?p=../bus_exp/pci-isa.html http://www.cyberresearch.com/store/product/3228.2.htm PCI->ISA Bridge kits: http://www.costronic.com/Ev71p.htm -- Keith
From: Keith Williams on 4 Feb 2005 09:53 In article <c0m501t6gvk990vrer0tafivs9nhrmmnbc(a)4ax.com>, jkirwan(a)easystreet.com says... > On 3 Feb 2005 15:12:33 -0800, aiiadict(a)gmail.com wrote: > > >Modern computer with PCI only, need to plug in an ISA card. > > The southbridge or PCI-ISA bridge chip can only exist with "side-band" channels > to the main chipset. No side-band channels/signals are needed. > There is only one of these possible, and then only if the > rest of the chipset supports the southbridge concept. Only one "subtractive decoder" is possible. Southbridges use "subtractive decoding", so only one southbridge is possible. > The side-band channels do > not exist as signals on the PCI bus, so I don't believe that it would be > possible to do a PCI board that provides full ISA -- more particularly, support > for ISA DMA. Perhaps, but only because the DMA controller's addresses are already used by the southbridge. ISA busmaster is also a likely "issue". > You might be able to get by with some specialized FPGA or ASIC for > the purposes of a reduced ISA feature set connecting to the PCI (no DMA and with > subtractive decoding for the ISA address space.) The PLX 9052 is a PCI to ISA bridge. IIRC it's only a PCI target device though. -- Keith
From: Nico Coesel on 4 Feb 2005 11:25 Jonathan Kirwan <jkirwan(a)easystreet.com> wrote: >On 3 Feb 2005 15:12:33 -0800, aiiadict(a)gmail.com wrote: > >>Modern computer with PCI only, need to plug in an ISA card. > >The southbridge or PCI-ISA bridge chip can only exist with "side-band" channels >to the main chipset. There is only one of these possible, and then only if the >rest of the chipset supports the southbridge concept. The side-band channels do >not exist as signals on the PCI bus, so I don't believe that it would be >possible to do a PCI board that provides full ISA -- more particularly, support >for ISA DMA. You might be able to get by with some specialized FPGA or ASIC for >the purposes of a reduced ISA feature set connecting to the PCI (no DMA and with >subtractive decoding for the ISA address space.) > >I haven't heard of such a thing, though. I think it is possible if the ISA card can use 1 interrupt or share interrupts. You'll need some intelligence to convert ISA DMA to PCI bus mastering (which is more or less the same, only the addresses are generated at a different spot). The amount of I/O and memory addresses can be preset on the PCI card so substractive addressing isn't needed. -- Reply to nico(a)nctdevpuntnl (punt=.) Bedrijven en winkels vindt U op www.adresboekje.nl
From: Jonathan Kirwan on 4 Feb 2005 14:55
On Fri, 4 Feb 2005 09:53:19 -0500, Keith Williams <krw(a)att.bizzzz> wrote: >> The southbridge or PCI-ISA bridge chip can only exist with "side-band" channels >> to the main chipset. > >No side-band channels/signals are needed. Why do you say this? It's certainly been true for as long as I've worked on these chipsets. That does date back to the P2, but have things changed? I doubt it. Jon |