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First post, by iulianv

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I've done some reading (here mostly, but on other sites too) on RAM caching capabilities of various socket7 chipsets, and so far the following things are a bit unclear to me:

1. 430HX seems to be the "champion" here - most mainboards (those with an 8-bit TAG chip) can only cache 64MB of RAM, but 256MB or 512MB can be cached if one uses a 10-bit TAG, an 11-bit TAG or two 8-bit TAG chips.

So far I could only "find proof" of the last choice - dual-socket (or single-socket with the same PCB) Tyan boards seem to be using two 8-bit TAG chips - I found some detailed photos here:

http://www.ebay.co.uk/itm/Tyan-Tomcat-III-S15 … 7-/260848811945

Can someone provide examples of boards using 10-bit or 11-bit TAG chips? Or at least an example of such TAG chip part-number...

2. I've read in various places that Windows uses the RAM "from the top down", so using more RAM than the cacheable size will almost always impact performance. Is this true for all Windows versions? I have WinNT4 installed on a 430VX board with 128MB of EDO RAM, and it feels pretty snappy in all applications except web browsing (but this can be due to today's usually "overloaded" web pages).

I'll dig that system up and perform some more testing (64MB of RAM instead of 128, and 10/100 PCI NIC instead of 10 ISA), but I'm asking the question anyway: assuming system/application requirements not exceeding the cacheable RAM size, is there any performance penalty in running Windows (NT4 in particular) with more RAM than the chipset can cache? If the requirements do exceed the cacheable RAM size, I assume using uncached RAM is still a lot better than swapping to the hard-drive...

Reply 1 of 5, by elianda

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i430FX66 max. 64 MB
http://mail.lipsia.de/~enigma/neu/pics/mainbo … rd_i430fx66.jpg
TAG RAM is the small long one right of the CPU socket
UM61256FK-15

i430VX max. 64 MB
http://mail.lipsia.de/~enigma/neu/pics/i430VX.jpg
right of CPU socket
ISSI IS61C256AH-12N

i430HX max. 512 MB
http://mail.lipsia.de/~enigma/neu/pics/gigabyte_ga586hx2.jpg
lower left edge of PCB
extended by the socketed IC
original: W24129AK-12
socketed: UM61256FK-15

i430TX max. 64 MB
http://mail.lipsia.de/~enigma/neu/pics/mainbo … d_ga_586tx3.jpg
lower edge of PCB
W24129AK-12

SIS5591/5595 - max. 64 MB
http://mail.lipsia.de/~enigma/neu/pics/ga586sg.jpg
left below socket
W24129AJ-12

i430NX has Async PB cache.

uncached RAM has around 40% of the speed of cached RAM as a raw estimate.
This depends strongly how it is used.
NT4 uses the memory top down. If it feels snappy it is just because NT4 is fast anyway, so it could be twice as fast on your system 😉.

Ofcourse there is always the problem, what helps more? More slow memory or faster less memory? This depends on your applications. If 64 MB is enough f.e.

Better approach is ofcourse to switch to a solution with cached memory.
Plug-In a K6-III f.e.

Reply 2 of 5, by iulianv

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I kind of like that mainboard, it looks pretty neat (ATC-1030), so I'll leave it with 64MB, go for a P233MMX and try to keep the RAM requirements for WinNT under 64MB. I also have a K6-3 in plan, but for another board (a PC Partner, MVP3-based, will also run WinNT4)...

Thanks for the double-TAG Gigabyte HX example - I also want to get my hands on a 430HX and I'm collecting choices 😀. Still looking for a 10- or 11-bit TAG chip example, all in your list seem to be 8-bit (I assume it's the "8" in the "16Kx8" or "32Kx8" datasheet description, right?)...

Reply 3 of 5, by iulianv

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I've been looking for 430HX-based board examples, and another curiosity occurred: is there any such board with "standalone" BIOS battery, or do they all have them "embedded" in the Dallas RTC?

Reply 4 of 5, by megatron-uk

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I've got an old Gigabyte 586HX board somewhere and I definitely remember buying the tag ram upgrade because I had significantly more than 64mb (it ended up with something like 192mb, IIRC). I'll see if I can dig it out.

My collection database and technical wiki:
https://www.target-earth.net

Reply 5 of 5, by sliderider

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iulianv wrote:

I've been looking for 430HX-based board examples, and another curiosity occurred: is there any such board with "standalone" BIOS battery, or do they all have them "embedded" in the Dallas RTC?

Those RTC chips can be hacked after the internal batteries die to use either a coin cell or a AA battery holder. You just have to know where to cut them open to access the +/- terminals.