Talk:Industry Standard Architecture

message: 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)
thread_title: Pinout error

message: 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)
thread_title:  What does that picture in the technical section mean???? 

message: 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)
thread_title:  How many PCI cards can be plugged to Pentium 4 machine without losing performance?  

message: 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)
thread_title:  386 ISA 

message: By the picture of 16 Bit ISA pins, there seems to be no irq15 pin. In Barry Brey's book "The Intel Microprocessors 8086/8088 <...> Pentium 4 Architecture, Programming, and Interfacing", 6th edition, D6 pin is called IRQ15 instead of IRQ13 on the picture. One more link: http://www.byminsk.com/isa.htm - the table there says D6 is IRQ15, not 13.
I think it's really irq15, because irq13 is FPU error interrupt, and it shouldn't be used by ISA devices, while irq15 _is_ used by secondary IDE controller.
If i am right, fix this error in the picture someone pls (i won't do this 'cause i am not quite sure that i'm right).  —Preceding unsigned comment added by 91.192.188.185 (talk) 15:32, 16 September 2008 (UTC)
replies: text: The picture, at low resolution is not clear, but the Specification is that D6, or the 6th pin on the trace side is Irq15. ( And you are right that irq15 is secondary DASD/HD controller, ) but a coprocessor card could use Irq_13 as a service routine. ( there are cards that work this way. )  —Preceding unsigned comment added by 69.232.207.6 (talk) 12:20, 24 February 2011 (UTC)
thread_title:  IRQ 15/13 

message: :Memory address decoding for the selection of 8 or 16-bit transfer mode was limited to 128 KiB sections - A000-BFFF,C000-DFFF, E000-FFFF leading to problems when mixing 8 and 16-bit cards, as they could not co-exist in the same 128 KiB area. 
Is this referring to DMA?  For general memory or I/O port transfers, each individual bus cycle takes a full, independent 24-bit address with the data length (8 or 16 bits) and memory or I/O selected by the *MEM CS 16 and *IO CS 16 lines.  The IBM AT technical reference manual, the original and authoritative [but not comprehensive or always thorough] definition of the AT bus, makes no reference to any constraints for mixing 8- and 16-bit cards.)
: added by  in [ this edit]
: This is related to memory cycles. MEMCS16 had to be asserted based only on the early unlatched address bits in the extended 16 bit connector part (these lines were called LA17-LA23) before the whole buffered address was present (at the standard 8-bit connector part; this time missing bits 20-23 on SA0-SA19). While later chipsets waited for MEMCS16 evaluation until the time SA0-SA19 were valid (indicated by ALE), the original AT would ignore MEMCS16 at that point and treat the cycle as an 8-bit cycle. See for example the diagrams in . 89.247.214.185 (talk) 11:44, 16 November 2008 (UTC)
thread_title: 8/16-bit Incompatibilities

message: 8-bit I/O is the least complex signaling. Such bus phase occurs when , , ,  which indicate that  is available. Maximum transfer time with an  bus clock is  or 4 CLK cycles. Driving  signal 16-bits from card and SBHE is driven high by the motherboard when  is valid.aau.dk - Extending ISA Soundcardtechfest.com - ISA Bus Technical Summarytechfest.com - THE ISA AND PC/104 BUScs.ucr.edu - The ISA Bus: A Brief Introductionbooks.google.com - Data acquisition techniques using PCs by Howard Austerlitz 
::It's too full of acronyms to be explicable, and a cycle-by-cycle description of bus timing is too much detail for an encyclopedia article. --Wtshymanski (talk) 14:54, 4 May 2011 (UTC)
thread_title: Interfacting moved from article

message: What is the maximum designed length allowed for the bus signal wires?
I'm hacking an old device that had an embedded motherboard which can not be replaced, so using ribbon cables and card-edge slot adapters, I've sort of extended the ISA bus out of the one box and into the rear of another PC to use one of its ISA slots. The ribbon cable length is something like two feet long, and this is working just fine. Seems odd for it to work so well.
I thought for sure either the computer wouldn't POST or the ISA device would fail randomly but it's all working fine. I can not find info on the max length of the bus anywhere, so who knows, this may be operating well within whatever the spec actually is. Though I will probably wrap the extender ribbon in foil to provide RF shielding outside the normal RF-enclosure. 216.56.13.252 (talk) 01:54, 17 September 2011 (UTC)
replies: text: The IBM PC Technical reference has a schematic for the expansion bus box. I think it had a 6 foot cable, and data latches on each end. See if you can find it.  — Preceding unsigned comment added by 173.200.183.146 (talk) 22:32, 24 July 2012 (UTC)
thread_title: Maximum ISA bus length?

message: "A derivative of the AT bus structure is still used in the PCMCIA standard, Compact Flash, the PC/104 bus, and internally within Super I/O chips."
Big discusion of ATA/IDE in the article, but the introduction doesn't even mention it.  — Preceding unsigned comment added by 203.206.162.148 (talk) 09:55, 17 September 2014 (UTC)
thread_title:  IDE 

message: Use of the term "XT-IDE" in reference to the 8-bit version of IDE used in vintage XT-class machines should be avoided to prevent confusion with the modern open-source XT-IDE cards, which provide an ATA-compatible interface for XT-class machines, and is in fact totally incompatible with these vintage 8-bit IDE drives. The vintage 8-bit drives and interfaces were commonly known as IDE-XT when they were in current use in the late '80s and early '90s, or today also by the retronym XTA.  — Preceding unsigned comment added by 74.105.4.154 (talk) 02:00, 5 October 2021 (UTC)
replies: text: We don't define things here (WP:OR). WP is an encyclopedia and we describe things as they are with terminology that is commonly used. For such a change you'd require a very good WP:RS. --Zac67 (talk) 06:50, 5 October 2021 (UTC)
thread_title:  IDE-XT vs. XT-IDE (and XTA) 

message: I believe pin B4 of the connector is mislabeled. It says IRQ2, which agrees with http://www.hardwarebook.info/ISA#Pinout, but that is not an authoritative source. Intel's ISA Bus Specification and Application Notes (page 62), linked in the Further Reading Section specifies that pin as IRQ9, as does the PC/104 spec (page 20), and so does the user manual of a PC/104 compute board I'm designing a back plane for. --180.150.103.66 (talk) 05:18, 29 January 2022 (UTC)
replies: text: Well spotted. For the 16-bit AT bus, IRQ2 from the original PIC was repurposed for cascading the second PIC and its slot contact was rerouted to IRQ9 on the second PIC. This is already detailed in Interrupt request (PC architecture)#x86 IRQs, albeit without source. https://www.pc-control.co.uk/isa_bus_pinout.htm labels B4 as IRQ9. --Zac67 (talk) 07:31, 29 January 2022 (UTC)
thread_title:  Pin B4 Appears To Be Incorrect? 

message: There's no mention of the physical sizes of cards meeting the standard, whereas it is covered in the articles on PCI and PCI Express. Though, maybe those articles are just unusually good, given AGP and PCI-X are also missing it.
--Roxor128 (talk) 03:28, 31 August 2022 (UTC)
thread_title:  Physical Dimensions