Talk:Industry Standard Architecture

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The 8-bit and 16-bit bus pinouts have an error; the IRQ1 pin should be labeled as IRQ2 pin. IRQ0 and IRQ1 are not available on the ISA bus, as they go directly to the relevant hardware (programmable interval timer and keyboard controller). 91.153.27.229 (talk) 08:29, 17 July 2008 (UTC) Jepael[reply]

I think the information here is out of date, so far as I know no PCs' are being made with the ISA bus, typically they have several PCI slots and usually an AGP slot.

Nezumi Replies: by the way. ISA Bus speed is 8MHz for a 16 bit ISA and 4.77 for a 8 bit ISA

There's still significant demand for ISA on industrial motherboards, apparently; legacy devices, plus the fact that many of them don't need all that much bandwidth but *do* need a lot of different devices plugged into them. This last rules out PCI, and USB has close to zero real-time capacity. I have in my lap a catalogue for iei electronics with P4 motherboards with two ISA slots; www.ieiworld.com, if you don't believe me. I'll leave it to the cleverer to edit the actual text.

Apart from internal use on current PC-compatible systems - I'm not so sure about this: most current motherboards use an LPC bus instead, to save having to route all the traces ISA requires.

What does that picture in the technical section mean????

please tell me or die

... The top picture is a photo of the plastic ISA-type connecting slots that ISA circuit boards plug into. The picture is taken at a strange angle, so look at the PCI article to see what these slots look like when viewed directly at them. The drawings below the picture are just top views of the connectors with notes indicating what each physical connection is used for. It is like unplugging your computer from the wall, pointing the prongs of the plug at your face and putting little labels on them to explain what each of them does. So now I don't die, huh? R.Giltner 20:14, 14 December 2006 (UTC)[reply]

How many PCI cards can be plugged to Pentium 4 machine without losing performance?

I have got a situation in my project to use 5 PCI video frame grabber cards and to process all card datas simultaneously.

1) Wrong page. Don't ask about Eskimos on a page about escargot, and don't ask about PCI on a page about ISA.

2) This isn't a message board where this type of thing is appropriate to ask. You're really only supposed to discuss the article and info that is currently or may subsequently be included therein.

3) Unless there are resource conflicts, you can plug as many PCI cards into your PC as it can hold without losing performance. Using them all simultaneously is another matter, and could saturate the bus, causing lag. 12.75.48.97 06:38, 22 September 2006 (UTC)[reply]

8 bit ISA?

As far as i recall, the name ISA did not surface untill the 16 bit extension of the IBM-PC slot. So, it's a bit like referring to a Model B as a Model T--which i'm sure also happens. [Then there's the whole Model A vs `Model A' nonsense, but i digress.]
—StationaryTraveller 03:56, 11 May 2006 (UTC)[reply]

Since the shorter 8-bit slots continued to be used in systems even after the longer 16-bit slots were introduced, and either slot could accomodate the vast bulk of cards, I don't see why it wouldn't make sense to call both of them by the same name, and differentiate by the number of bits they used. If I opened up my 386 and found two long slots and a short slot, yet I could plug my original Sound Blaster into any of them, would it really make sense to just call the long ones ISA? 12.75.48.97 06:29, 22 September 2006 (UTC)[reply]

The article may be a little incorrect. IBM called them the "PC XT" or "PC AT" bus well into the mid-1990s. "ISA Bus" was a term invented by IBM's competitors at some point. 64.171.162.77 01:35, 10 December 2006 (UTC)[reply]

DMA and bus mastering

This article states that the ISA bus allows for bus mastering and has DMA channels, but the ISA bus was controlled by a separate DMA controller. From what I've read this was one of the main reasons why PCI rendered ISA obsolete... PCI devices could take control of the bus themselves, so nothing external was required to control traffic. Could anyone clarify how this works, and the differences between ISA and PCI bus mastering? How is it that an ISA device has DMA channels but still had request/ack channels... is this just part of the device handshaking protocol? —Preceding unsigned comment added by 66.142.239.75 (talk) 17:41, 16 September 2007 (UTC)[reply]

ISA and clone manufacturers

How were clone manufacturers able to use ISA when it was created by IBM? Why did not IBM bann this? Teveten 14:59, 4 October 2007 (UTC)[reply]

IBM did not create ISA, IBM created XT and AT buses. ISA is a generic name for architecture that is compatible with XT and AT. Clone manufacturers reverse-engineered the IBM busses the same way they did the rest of the PCs, by separating requirements developers from engineers so the end design was a copy of the requirements, but not the actual bus (refer to IBM PC Compatible). At least that's the way I understand it. Spacefem 15:27, 28 October 2007 (UTC)[reply]

OK. But why every PC-compatible story tells about reverse engineering BIOS, not about reverse engineering XT and AT buses?Teveten 19:51, 4 November 2007 (UTC)[reply]

IBM was under a government anti-trust decree which required open access to their hardware interfaces. This decree was lifted shortly before IBM introduced MCA. So, the ISA/AT bus wasn't reverse-engineered, IBM published it. 71.134.252.36 (talk) 03:45, 20 August 2008 (UTC)[reply]

Out of spec 32 bit version of the ISA bus

In an old zenith datasystems 386DX machine (made in '86 or '87) there is an vesa local bus like extention to the good old 16 bit ISA bus, except that the print connector sizes are the same as in the isa bus (the connectors are a little more than dubbeled in lenght).

The following add on cards are connected to this bus: - a card carrying the processor and bios - two huge cards carring 4MB of XT like memory chips each. - the video card (CGA/EGA connector), which includes an serial mouse port on the video card. - two MFM Harddisk drive controllers. Only those disks to one of the controllers are recognized by the OS. It seems the other one does provide several MB of virtual memory per huge MFM disk connected - and one that seems to be a data accuisition card.

It seems the memory bus is extended (like VESA) to those extention cards, aim: to be able to do DMA?

Is this an unstandardized update / extention for the ISA bus, or is it a rare extention to ISA16? —Preceding unsigned comment added by 213.84.80.86 (talk) 16:35, 23 November 2007 (UTC)[reply]

386 ISA

The 386 extention by Zenith to ISA is called a 386 slot. See Google 'Zenith 3300' for more information. Some other manufacturers also have separate 386 slots on their early 386 boards. Purpose seems to be extending the memory bus to >286 capabilities. —Preceding unsigned comment added by 213.84.80.86 (talk) 18:10, 23 November 2007 (UTC)[reply]