Shuttle HOT-409 L2-Cache WB performance \ VOGONS

Shuttle HOT-409 L2-Cache WB performance

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First post, by majestyk

Posted on 2025-03-22, 18:34

majestyk Offline

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I just cleaned my old HOT-409 and did some tests with the latest BIOS.
https://theretroweb.com/motherboards/s/shuttl … ot-409-ver.-2.2

As expected L2 cache mode is Write Back. I know mainboards with this chipset (OPti 495SX) that have one or two additional sockets for Dirty-TAG chips.
THe HOT 409 doesn´t seem to have a Dirty chip and the BIOSes I tried didn´t reserve one TAG-data bit for dirty, so performance is a bit disappointing.
Then I discoverd an empty DIL-20 socket between CPU and VLB-slot #1. Could this be populated with a DIL-20 SRAM as Dirty chip??
All pictures I found show the HOT-409 with this socket empty.

The attachment hot409_dip20.JPG is no longer available

Anyone tried to add a Dirty chip?

Reply 1 of 4, by Disruptor

Posted on 2025-03-23, 17:12

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Please ask heise's ctcm first to see whether a dirty tag ram could help.
https://ftp.heise.de/pub/ct/ctsi/ctcm17a.zip

And please add a screenshot (PNG format is best) of SpeedSys' cache chart.

That DIL looks like it fits a chip that enables bus master on that / a VL slot. You won't need it for a graphics card or an IDE controller. But there already maybe another one for the other VL slot (to drive a SCSI controller).
It is not for cache.

Reply 2 of 4, by majestyk

Posted on 2025-03-23, 18:16

majestyk Offline

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All ctcm versions say unmistakably "Dirty TAG -> n/a" and in Speedsys the L2 performance is 40 MB/s reading and 20 MB/s moving, a difference that would be smaller if a Dirty TAG was active.

Still, I think you are right about the DIP 20 socket, I did some measuring today and couldn´t find any connections to the Cache / TAG address lines at all. It´s probably a VLB-related circuit.

Reply 3 of 4, by Disruptor

Posted on 2025-03-23, 19:05

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You won't be able to see the difference from an added dirty tag in SpeedSys' cache chart.

Reply 4 of 4, by majestyk

Posted on 2025-03-23, 20:04

majestyk Offline

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Sorry, mixed that up - in memory performance you can see it:

The attachment DirtyTag.JPG is no longer available

The attachment NoDirtyTag.JPG is no longer available

Sadly, the result is the same, no Dirty Tag on the 409, not physical, not in ctcm, not in Speedsys.

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