Cheapest - stick with 8MB of 8x 1MB 30pin simms. ISA memory expansions will only slow whole computer down. Up to 66MHz 8MB was "fine". 12MB would be optimal, and 16MB is too much with nothing being able to run smoothly on such CPU using that much.
easy - seems two people are manufacturing new 4MB modules, ~$40 for 16MB https://www.tindie.com/products/siliconinside … -dram-simm-kit/ or Newly made 4MB 30pin SIMMs
smart - make your own
cheap - desolder 4 sockets and hack solder one 16MB 72pin simm with kynar wires in place.

Agree - Do not use any ISA based add-on memory unless you just need some EMS (not XMS/Extended) or it will slow all the memory down.
I have never had much issue with 4x4Mb 30 pin on a 486 when the board supports it (most do) but have more 486 running with 8Mb than with more than....

Don't use an EMS board in anything past a 286 really, because a lot of stuff will detect EMS and 386+ and assume EMM386 and promptly crash.

All the fluidly playable on 486 games will be fine with 8MB... Win95b and c is nicer with 16MB, but it's not all that great on lower speed 486, which are likely to be the ones with 30pin RAM so expecting to turn a 486DX33 into a Win9x beast with spendy RAM isn't all that realistic. You can even play some of the "8MB required" things on 6MB (Not a config you get without weird modules really) and see speedup on "4MB minimum 8MB recommended" with 6MB. Just noting that really so you understand that an 8MB config isn't "barely coping" with those types of games, not all crammed in not a byte to spare, needs breathing room, sort of thing.

(Okay if you really must know I had a 2MB 72pin SIMM back in the day bought intending to use in an Amiga Accelerator, but it got added to my 4MB PC while it was waiting. 2MB was meant to avoid interference with the A1200 PCMCIA slot, but by the time I got one, remapping had been figured out and you could stick 4 to 16MB in one no problem.)

However, you have forgotten that theoretically you can also install an OverdriveDX4, bringing the computer to blazing 100Mhz without distorting the cpu class with pentium, 5x86 etc…

in this case maybe, 32Mb wouldn't be more appropriate?

Robin4 wrote on 2022-11-20, 00:14:

Also have an extra question on the motherboard cache of these boards.

Most of this boards have 20 nS of chips installed, but would 15nS giving me any benefits on these first gen VLB board.. And does a capacity more then 128KB matter on these board. I my mind i think of upgrade it at least to 256kb.

Yes, cache is important.
Basically your cache should couverage all of your DRAM, called cacheable area.
If you have a (in most cases) faster Write Back (WB) cache, you need a dirty bit in your TAG ram, that results in half of a Write Through's (WT) cacheable area .
You gain most benefit from raising a cacheless board to 64 KB of cache. Significant difference is also when doubling from 64 KB to 128 KB. All following double ups are less impacting.

If you want to hit the maximum amount of DRAM in your board, you may consider to switch from WB to WT cache.
Cacheable area in a 486:
64 KB should be good for 8 MB WB / 16 MB WT
128 KB 16 MB WB / 32 MB WT
256 KB 32 MB WB / 64 MB WT
512 KB 64 MB WB / 128 MB WT
1024 KB 128 MB WB / 256 MB WT

Disruptor wrote on 2022-11-20, 08:43:

Yes, cache is important. Basically your cache should couverage all of your DRAM, called cacheable area. If you have a (in most c […]
Show full quote

Robin4 wrote on 2022-11-20, 00:14:

Also have an extra question on the motherboard cache of these boards.

Most of this boards have 20 nS of chips installed, but would 15nS giving me any benefits on these first gen VLB board.. And does a capacity more then 128KB matter on these board. I my mind i think of upgrade it at least to 256kb.

Yes, cache is important.
Basically your cache should couverage all of your DRAM, called cacheable area.
If you have a (in most cases) faster Write Back (WB) cache, you need a dirty bit in your TAG ram, that results in half of a Write Through's (WT) cacheable area .
You gain most benefit from raising a cacheless board to 64 KB of cache. Significant difference is also when doubling from 64 KB to 128 KB. All following double ups are less impacting.

If you want to hit the maximum amount of DRAM in your board, you may consider to switch from WB to WT cache.
Cacheable area in a 486:
64 KB should be good for 8 MB WB / 16 MB WT
128 KB 16 MB WB / 32 MB WT
256 KB 32 MB WB / 64 MB WT
512 KB 64 MB WB / 128 MB WT
1024 KB 128 MB WB / 256 MB WT

But my IBM 486 PC330 accept maximum of 256k cache and maximum of 128MB of ram, how is possible?

AlessandroB wrote on 2022-11-20, 16:48:

Disruptor wrote on 2022-11-20, 08:43:

Cacheable area in a 486: 64 KB should be good for 8 MB WB / 16 MB WT 128 KB 16 MB WB / 32 MB WT 256 KB 32 MB WB / 64 MB WT 512 K […]
Show full quote

Cacheable area in a 486:
64 KB should be good for 8 MB WB / 16 MB WT
128 KB 16 MB WB / 32 MB WT
256 KB 32 MB WB / 64 MB WT
512 KB 64 MB WB / 128 MB WT
1024 KB 128 MB WB / 256 MB WT

But my IBM 486 PC330 accept maximum of 256k cache and maximum of 128MB of ram, how is possible?

If your board looks anything like https://theretroweb.com/motherboards/s/ibm-pc … 71,-pc-350-6581 , it uses the standard consumer board cache design with 8 tag bits in write-through or 7 tag bits in write-back mode. This means the limits posted by Disruptor apply to your board. Your board can address 128MB of RAM, but only the lower part of it is cached.

AlessandroB wrote on 2022-11-20, 07:23:

However, you have forgotten that theoretically you can also install an OverdriveDX4, bringing the computer to blazing 100Mhz without distorting the cpu class with pentium, 5x86 etc…

in this case maybe, 32Mb wouldn't be more appropriate?

I agree. If you are targeting Windows 95 or higher, I'd go with 32MB. It will cut down on swapping and unlike 1996, it no longer costs as much as a decent used car.

* Going over 64MB can cause uncacheable memory areas on some chipsets which might slow your system down, your mileage may vary.
* Don't use ram attached over the ISA bus on a system that runs faster that 12 Mhz.
* You want a system memory cache with any system board that runs faster than 16Mhz. The first 32KB of memory cache has a big impact on performance, with diminishing returns each time you double the size of it after that. So going from 32KB to 64Kb has less impact than the first 32KB, but has a bigger impact than going from 64KB to 128KB, which has a bigger impact than going from 128KB to 256KB, etc. The performance impact of going from 512KB up to 1MB cache on a 486 gets pretty hard to measure outside of some contrived edge cases. I still do it when I can, but it's getting into the category of "how many angels can dance on the head of a pin".

mkarcher wrote on 2022-11-20, 16:57:

AlessandroB wrote on 2022-11-20, 16:48:

Disruptor wrote on 2022-11-20, 08:43:

Cacheable area in a 486: 64 KB should be good for 8 MB WB / 16 MB WT 128 KB 16 MB WB / 32 MB WT 256 KB 32 MB WB / 64 MB WT 512 K […]
Show full quote

Cacheable area in a 486:
64 KB should be good for 8 MB WB / 16 MB WT
128 KB 16 MB WB / 32 MB WT
256 KB 32 MB WB / 64 MB WT
512 KB 64 MB WB / 128 MB WT
1024 KB 128 MB WB / 256 MB WT

But my IBM 486 PC330 accept maximum of 256k cache and maximum of 128MB of ram, how is possible?

If your board looks anything like https://theretroweb.com/motherboards/s/ibm-pc … 71,-pc-350-6581 , it uses the standard consumer board cache design with 8 tag bits in write-through or 7 tag bits in write-back mode. This means the limits posted by Disruptor apply to your board. Your board can address 128MB of RAM, but only the lower part of it is cached.

Yes, the board is the one you indicated. a question that may also be of interest to the author of the post ... what is the method to measure the cached ram from that not? that is, if after the 32 megs the speed collapses, can it be seen in some way with any software???

AlessandroB wrote on 2022-11-20, 20:05:

Yes, the board is the one you indicated. a question that may also be of interest to the author of the post ... what is the method to measure the cached ram from that not? that is, if after the 32 megs the speed collapses, can it be seen in some way with any software???

Yes, there are tools to measure which parts of the main memory are cached. cachechk is included in the "dosbench" collection, but it does not support systems with more than 64MB of RAM properly. Also, there is ctcm by the German computer magazine c't. I'm quite confident it does support more than 64MB of RAM, but you should run version 1.7 with "/NOP" on the systems without MMX due to a bug to prevent a crash (but that crash happens after information about the cachable area has already been printed).

AlessandroB wrote on 2022-11-20, 07:23:

However, you have forgotten that theoretically you can also install an OverdriveDX4, bringing the computer to blazing 100Mhz without distorting the cpu class with pentium, 5x86 etc…

yes, you can totally buy $200 collectors CPU to put in old motherboard just to have more problems 😀

AlessandroB wrote on 2022-11-20, 07:23:

However, you have forgotten that theoretically you can also install an OverdriveDX4, bringing the computer to blazing 100Mhz without distorting the cpu class with pentium, 5x86 etc…

in this case maybe, 32Mb wouldn't be more appropriate?

I have other machine doing that task.. Iam also planned to build a faster 486.. This 486 33Mhz was more, `when ever i dont have enough 386 motherboards available plan`

Was thinking of building an 486 100 / 120 Mhz machine.. But plan is skipped. I think its better to build a socket 5 pentium 75 / 90 instead.
Bios of the socket 5 boards would be newer, so hope it would support higher capacity hdds. (at least3,2 or 4GB by bios.) Or using a NIC with LBA Eprom on it for max 8.4GB support)

GTA , Need for speed (2), blood, duke nukem, Red alert 95 runs smoother on a first class pentium.. I dont use it for 3D games what a faster pentium class machine would do.
But it can take over a lot of later 486 earlier pentium games.

And yeah 32MB would be fine on that machine.

Disruptor wrote on 2022-11-20, 08:43:

Yes, cache is important. Basically your cache should couverage all of your DRAM, called cacheable area. If you have a (in most c […]
Show full quote

Robin4 wrote on 2022-11-20, 00:14:

Also have an extra question on the motherboard cache of these boards.

Most of this boards have 20 nS of chips installed, but would 15nS giving me any benefits on these first gen VLB board.. And does a capacity more then 128KB matter on these board. I my mind i think of upgrade it at least to 256kb.

Yes, cache is important.
Basically your cache should couverage all of your DRAM, called cacheable area.
If you have a (in most cases) faster Write Back (WB) cache, you need a dirty bit in your TAG ram, that results in half of a Write Through's (WT) cacheable area .
You gain most benefit from raising a cacheless board to 64 KB of cache. Significant difference is also when doubling from 64 KB to 128 KB. All following double ups are less impacting.

If you want to hit the maximum amount of DRAM in your board, you may consider to switch from WB to WT cache.
Cacheable area in a 486:
64 KB should be good for 8 MB WB / 16 MB WT
128 KB 16 MB WB / 32 MB WT
256 KB 32 MB WB / 64 MB WT
512 KB 64 MB WB / 128 MB WT
1024 KB 128 MB WB / 256 MB WT

So upgrading an earlier 486 boards with 8MB or 16MB memory and cache ram from 128Kb to 256Kb is just waisting on resources and money?
I dont think such a board would ever need more ram what i suggested here.

The system would only run MS-DOS and maybe windows 3.1 or 3.11.

Same like a 386 Motherboard upgrading from 128KB to 256KB doest make sense too.. (because on normal use it never exced the 8MB limit at all)

* Don't use ram attached over the ISA bus on a system that runs faster that 12 Mhz

Okey, thats why some 386 motherboard have seperate memory add-on boards with faster 32-bit acess to the cpu available with that special slot.. So 16 bit is slot in every situation.

Robin4 wrote on 2022-11-21, 01:03:

So upgrading an earlier 486 board with 8MB or 16MB memory and cache ram from 128Kb to 256Kb is just waisting on resources and […]
Show full quote

So upgrading an earlier 486 board with 8MB or 16MB memory and cache ram from 128Kb to 256Kb is just waisting on resources and money?
I dont think such a board would ever need more ram what i suggested here.

The system would only run MS-DOS and maybe windows 3.1 or 3.11.

Same like a 386 Motherboard upgrading from 128KB to 256KB doest make sense too.. (because on normal use it never exced the 8MB limit at all)

I guess it is a waste of money in both cases.
When you hit the cacheable are limit, be sure you have memory relocation disabled in your BIOS.

rasz_pl wrote on 2022-11-20, 20:47:

AlessandroB wrote on 2022-11-20, 07:23:

However, you have forgotten that theoretically you can also install an OverdriveDX4, bringing the computer to blazing 100Mhz without distorting the cpu class with pentium, 5x86 etc…

yes, you can totally buy $200 collectors CPU to put in old motherboard just to have more problems 😀

Already tried an Pentium Overdrive 83 Mhz on an first gen older style 486 forex vlb motherboard.

The cpu runs, but its way to fast for that motherboard. You can see this, how it behave. It run a little bit with some of lag spikes and slow downs.

So i keep the older 486 5volt only boards, only for 486 DX class processors, or maybe an DX2 66 if i dont have an other option.

Disruptor wrote on 2022-11-21, 01:11:

Robin4 wrote on 2022-11-21, 01:03:

So upgrading an earlier 486 board with 8MB or 16MB memory and cache ram from 128Kb to 256Kb is just waisting on resources and […]
Show full quote

So upgrading an earlier 486 board with 8MB or 16MB memory and cache ram from 128Kb to 256Kb is just waisting on resources and money?
I dont think such a board would ever need more ram what i suggested here.

The system would only run MS-DOS and maybe windows 3.1 or 3.11.

Same like a 386 Motherboard upgrading from 128KB to 256KB doest make sense too.. (because on normal use it never exced the 8MB limit at all)

I guess it is a waste of money in both cases.
When you hit the cacheable are limit, be sure you have memory relocation disabled in your BIOS.

These are good tips!