There were probably some server systems that could do this. That much RAM would have cost tens of thousands of dollars though.

The 4GB thing is just a consequence of the 386 being a 32-bit CPU, like every x86 from that point until the release of the 64-bit processors. I don't think any manufacturers came up with a way to support that amount of RAM because it would have been: horribly expensive, very challenging technologically and not really worth it for what operating systems could support at the time.

If the motherboard could hold 4000 1mb EDO sticks, sure.

I think most boards would top out at 8x4mb for 32mb.

Maybe there would be boards with 12 or 16 simms but x86 servers weren't as common so I doubt you'd ever see much more than 64/128mb tops.

Yes, the 80386 can address 4 GB of physical memory.
And 64 TB of virtual memory.

keenmaster486 wrote on 2022-12-21, 22:54:

There were probably some server systems that could do this. That much RAM would have cost tens of thousands of dollars though.

IIRC even the top military super computers at the time never even got close to 4gb of memory in a single computer, it was theoretically possible to address that much memory but practically impossible from a physical technology standpoint to deploy that much. If you daisy chained systems together into a cluster you could in theory have 4gb of accessible memory but I doubt it would have been a very practical setup for any organization to build, manage or even power and run.

But heck the US military is well known for deploying monetarily and technologically impracticable systems... I'm looking at you F35 program so I guess if anyone had such a setup it would have been them.

My 386 motherboard has 8mb installed.
Sure DOS is limited to 4mb RAM but Win3x can address 16mb.

See my post:
Re: Made in USA 386.

The ram size would be limited by the memory controller in the chipset, yes?

OPTi 82C495 family Supports 64MB

for example: https://theretroweb.com/motherboards/s/shuttle-hot-317r2

I have not seen anything higher

Ahh the delima: cpu supports Y but chipset only supports Y/XX
Thanks douglar !

kolderman wrote on 2022-12-21, 23:56:

If the motherboard could hold 4000 1mb EDO sticks, sure.

Did 386 have edo?

no, edo 486 boards are rare tho and theres no performance benefit. The 4gb thing isn't real only exists on a piece of paper somwhere.

Sphere478 wrote on 2022-12-22, 03:03:

kolderman wrote on 2022-12-21, 23:56:

If the motherboard could hold 4000 1mb EDO sticks, sure.

Did 386 have edo?

Old full-size 80386 mainboards had local bus slots, similar to VLB, but proprietary.

They allowed the installation of 32-Bit memory boards.

With these slots, it would be possible to bypass the chipset's memory controller and install memory directly on the front side bus.

In essence, it's the same as using big ISA memory boards in an 80286 system.

Edit: Samples picture attached.

There were scenarios where rather large amounts of virtual memory on a central x86 server would point to various POS “terminals “ and other resources.

I am uncertain if any true x86 datacenter systems existed in the 1980’s but those could have 4gb of (physical + virtual memory) online even in the 80’s

Technically dual processor 386 systems existed, even Intel had a failed multiprocessor 286 server
Compaq s system pro dual unofficially supported up to 192mb of ram

And some “late” 386 motherboards supported 72pin simms allowing for 64mb+ depending on the board

So a technical max of 256mb is about it unless you can find a datacenter class system that was also x86

I'm not completely sure, but PC-MOS/386 was a very capable OS for 80386 systems, too.

It had a lot of memory-related mechanisms running.

Since it was multi-user/-tasking capable, it maybe could have made use of lots of memory.

Depending on the version, a single 386 PC could multitask DOS applications on 25 serial terminals, simultaneously.

Once I saw a 386 board claiming to support 128 MB, using 8 x 16 MB 30-pin SIMMs.

The most I actually got running is 64 MB, on a Shuttle HOT-327, 2 x 32 MB 72-pin SIMMs, FPM.
Only 32 MB is cached.

douglar wrote on 2022-12-22, 02:36:

The ram size would be limited by the memory controller in the chipset, yes?

So, with a 386 hooked to a compatible FPGA "chipset" hooked to a DDR3 chip...

Regardless I very much doubt anyone would have hooked 4GB of RAM to a 386. Consider how long it would take a 386 just to zero 4GB of RAM, much less do anything useful with it. I don't believe there's anything that would justify having 4GB on a 386 since it'd simply be too slow to work with amounts of data that large.

Warlord wrote on 2022-12-22, 04:03:

The 4gb thing isn't real only exists on a piece of paper somwhere.

It's in the design of the CPU and its 32-bit instruction set.

Theoretically it should be possible to build a 386 mainboard with current tech that would accept 4 GB RAM.

Just like current 64-bit CPUs support some astronomical amount of RAM, but a particular mainboard may be limited to 32 GB for example.

douglar wrote on 2022-12-22, 02:36:

The ram size would be limited by the memory controller in the chipset, yes? […]
Show full quote

The ram size would be limited by the memory controller in the chipset, yes?

OPTi 82C495 family Supports 64MB

for example: https://theretroweb.com/motherboards/s/shuttle-hot-317r2

I have not seen anything higher

I am using 8mb. Of FPM ram in my 386 motherboard. I mainly built it for DOS gaming and Win3.1

keenmaster486 wrote on 2022-12-21, 22:54:

There were probably some server systems that could do this. That much RAM would have cost tens of thousands of dollars though.

Hundreds of $thousands. Intel 386 was 1985. 32KB chip was $3, almost $400K just for ram chips. Ram prices actually went up substantially after 1985 😀 just after Intel decided to divest and shut down its ram factories fearing flood of cheap Japanese chips https://timeline.intel.com/1985/farewell-to-dram. Same 4GB of ram in 1988 would be cool $1.5mil.
Prices finally started coming down in 1991, the time AMD introduced Am386. 4GB would be back to "reasonable" $170K

Grzyb wrote on 2022-12-22, 05:03:

Once I saw a 386 board claiming to support 128 MB, using 8 x 16 MB 30-pin SIMMs.

The most I actually got running is 64 MB, on a Shuttle HOT-327, 2 x 32 MB 72-pin SIMMs, FPM.
Only 32 MB is cached.

1989 Mac SE/30 is one of the systems on a cheaper side with record ram size support at 128MB out of the box using off the shelf period correct components https://everymac.com/systems/apple/mac_classi … s/mac_se30.html