Talk:VMEbus

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In many ways the VMEbus is the pins of the 68000 run out onto a backplane. In most cases this is a bad design, because it limits you to systems similar to the chipset the bus was originally designed for. However, one of the key features of the 68000 was a flat 32-bit memory model, free of memory segmentation and other "anti-features". The result is that, while VME is very 68000-like, the 68000 is generic enough to make this not an issue in most cases.

Which is on the Pinouts.ru link OwenS | T | C | 22:15, 24 December 2006 (UTC)

"ADC" and "scaler" in photo caption

Could be just me, but I have no idea what an ADC or a scaler is in this context. If I were forced to guess, it would be "analog-to-digital converter" and perhaps a "video scaler", and I don't even know how much better my life would be for having this knowledge either way, but it's just a couple of things an editor with expertise might want to consider linking appropriately if they have the chance.--NapoliRoma (talk) 21:00, 18 December 2007 (UTC)

I agree that this isn't clear to most users. The "ADC" is definitely referring to "analog-to-digital converter". A scaler is a device which increments a counter every time it gets a pulse (such as http://www.caen.it/csite/CaenProd.jsp?idmod=24&parent=11). They are very common in nuclear and particle physics experiments, but it seems that there isn't a page for it. Samnotwil (talk) 14:47, 17 February 2015 (UTC)

Even Worse

The picture does not show a valid configuration. I know some ofthe modules in that backplane. The VME spec requires the left most module to be a bus arbiter and in the photo shown it isn't...unless this 'minicrate' has slot 1 on the right (some minicrates are like that as they are built to be mounted with the bus oriented vertically with the topmost module slot 1.

ADC - Analog to Digital Converter
Scaler - Counter.

The 'red' modules are nuclear instrumentation modules from CAEN (http://www.caen.it). The leftmost module is a CAEN V785 peak sensing adc, the second from the left a CAEN V830 latching scaler. I don't know what the CPU module is

The V785 locates the voltage peak of a signal during a gate pulse and digitizes the height of that peak.

The V830 has 32 counters which can be externally, internally or periodically latched for readout. The latch transfers the values of the counters to stable registers, and a multi-event memory allowing the counters to continue to increment.

Actual use today

As I read this blog post about linux WME drivers being integrated, I wondered what it was. I then read

It was first developed in 1981 and continues to see widespread use today.

I'd like to know what this actual use today is. —Preceding unsigned comment added by 82.75.158.226 (talk) 00:52, 4 August 2009 (UTC)

-------------> Shows Bias! <----------------

The author is showing strong prejudice against VMEbus with statements such as "this is a bad design" and "anti-features". Certainly VMEbus is dated and has its limitations, but it is used widely with great success. I've seen it implemented in high reliability applications, high speed applications and military applications. We shouldn't write technical descriptions with such bias. As a reader, I just want to know how it works! BTW - If you travel, many of the aircraft use flight control computers using VME. --Mach77 (talk) 18:22, 14 August 2009 (UTC)

Actually I took that to mean that the Intel busses had anti-features. Maybe I misunderstood.

35.9.55.200 (talk) 13:44, 26 October 2018 (UTC) RFOX

Section Ordering and Dependencies

The description section is written assuming that you have read the history section (e.g. not linking or describing the 68000). Many readers may want to read the description without any interest in the history. The Description section should either be the first section or should be independent of the history section. 130.207.218.196 (talk) 11:43, 28 August 2009 (UTC)

What does this even mean

I think this sentence needs rewording/rethinking.

"On the VME bus, all transfers are DMA and every card is a master or slave. "

For each transaction, there's one master and (except for some extensions supporting broadcast addressing) one slave. There's nothing to stop a module from being both a master (in one context) and a slave (in another). For example CPUs with dual ported memory can be masters to transfer data to/from other cards and slaves to attempts to transfer data to/from them.

Does DMA in this case meant there's no concept of 'port' based I/O as the Intel architecture had? In that case the term "memory mapped I/O" is more appropriate. Certainly if DMA means a block transfer that's just false. Single transfers are perfectly well supported and often done. 35.9.55.200 (talk) 13:43, 26 October 2018 (UTC) RFOX

Versa Module Europa vs Versa Module Eurocard

Wrt my clarification that was reverted, I see that, in the History section, we still say The result was first known as VERSAbus-E but was later renamed to VMEbus, for VERSAmodule Eurocard bus (although some refer to it as Versa Module Europa).[1] A quick search shows that both etymologies are accepted for the acronym. Please note that there are h/w manufacturers and magazines supporting the "VERSAmodule Eurocard" etymology, eg https://www.eckelmann.de/en/products-solutions/plant-automation and https://www.curtisswrightds.com/news/articles/long-live-vme.html. --Dipa1965 (talk) 23:11, 6 April 2019 (UTC)

I guess it wasn't clear to me what you were doing. I have restored a more verbose implementation and included refs. ~Kvng (talk) 16:17, 8 April 2019 (UTC)

What is a U?

The article uses "U" several times such as

• The current VME64 includes a full 64-bit bus in 6U-sized cards and 32-bit in 3U cards.
• In 1985, Aitech developed under contract for US TACOM, the first conduction-cooled 6U VMEbus board.
• In late 1987, a technical committee was formed under VITA under the direction of IEEE to create the first military, conduction-cooled 6U × 160 mm, fully electrically and mechanically compatible, VMEbus board co-chaired by Dale Young (DY4 Systems) and Doug Patterson (Plessey Microsystems, then Radstone Technology).
• ANSI/IEEE-1101.2-1992 was later ratified and released in 1992 and remains in place as the conduction-cooled, international standard for all 6U VMEbus products.

Is the "U" a unit of measure or an arbitrary marketing term? Is the VME bus "U" the same as 19-inch rack units? --Marc Kupper|talk 22:08, 28 June 2021 (UTC)

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