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VL-Bus Specifications

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First post, by gloomkeep

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First post! Not sure if this is the right place to post this or if anyone in the world other than me cares, but ...

I got back into 486 machines recently and have been trying to learn more about their architecture.

I haven't had much trouble finding information about the ISA bus (both at the electrical and functional levels), but I couldn't find much about the VESA Local Bus other than pinouts and minor discussions.

Perhaps to have access to the specifications you had to be part of an organisation with VESA membership back in the 90s?

So I got in touch with the VESA organisation and they agreed to release the VL-Bus specifications publicly / for free! It is not yet on their website, but I've attached:

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VLBUS20.PDF
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258.19 KiB
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420 downloads
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Fair use/fair dealing exception

VESA VL-Bus Standard Version 2.0 (Dated: November 1, 1993)

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PLUGPLAY.PDF
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43.92 KiB
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212 downloads
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Fair use/fair dealing exception

VESA VL-Bus Plug and Play Addendum (Dated: April 11, 1994)

Enjoy!

Reply 3 of 9, by Tiido

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This is excellent and will benefit a project or two I am slowly working on ;D

Thänk you very much ~

T-04YBSC, a new YMF71x based sound card & Official VOGONS thread about it
Newly made 4MB 60ns 30pin SIMMs ~
mida sa loed ? nagunii aru ei saa 😜

Reply 4 of 9, by Anonymous Coward

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Note that this is VL-bus specification 2.0. From what I remember, almost all motherboards and cards use specification 1.0.

"Will the highways on the internets become more few?" -Gee Dubya
V'Ger XT|Upgraded AT|Ultimate 386|Super VL/EISA 486|SMP VL/EISA Pentium

Reply 5 of 9, by Tiido

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The differences are very minor and only have to do with writeback cache and burst cycles it seems.

T-04YBSC, a new YMF71x based sound card & Official VOGONS thread about it
Newly made 4MB 60ns 30pin SIMMs ~
mida sa loed ? nagunii aru ei saa 😜

Reply 6 of 9, by root42

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Wow, this is amazing. Wonder what people will come up with...

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Reply 7 of 9, by gloomkeep

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Anonymous Coward wrote:

From what I remember, almost all motherboards and cards use specification 1.0.

I asked for the v1.0 spec a couple of weeks ago, but they don't have a copy anymore.

They've explained most of the (small) differences in the v2.0 spec, and on p28 you can, in a way, determine through ID bits what version is likely supported by a motherboard.

(i.e. it seems like it's up to the card to decide whether to fall back to v1.0 support or not)

spec_v2.0.png
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Tiido wrote:

The differences are very minor and only have to do with writeback cache and burst cycles it seems.

Yep, and 50MHz spec and 64-bit data bus.

Reply 8 of 9, by Jo22

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Thank you very much for your efforts, sir! 😀

"Time, it seems, doesn't flow. For some it's fast, for some it's slow.
In what to one race is no time at all, another race can rise and fall..." - The Minstrel

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Reply 9 of 9, by debs3759

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Very nice, thank you. Have added them to my library.

See my graphics card database at www.gpuzoo.com
Constantly being worked on. Feel free to message me with any corrections or details of cards you would like me to research and add.

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