You should be able to get 4Meg probably, maybe 5meg including what is already there.

How much memory does it currently show when you boot up? It should show up as 1meg given the numbers on the chips in the top bank of 8 chips.

Your current RAM is comprised of the 8 chips right to the VLSI chip, which each provide 256K storage locations of 4 bits (called 256K x 4), and the 4 chips in the big array of sockets, which each provide 256K storage locations of 1 bit (called 256K x 1), used for parity. As a 286 board uses 16 data bits and 2 parity bits per bank, you have two banks of 256K storage locations with 16+2 bits per bank. With the part of the board you show, it looks like it is ready to accept the 1MB you have also as 36 chips of 256K storage locations of 1 bit each (i.e. you replace all the HYB514256A (256K x 4) chips with four KM41C256P (or equivalent 256K x 1) chips, which you insert below the parity RAM). It is very unlikely that the 4-bit chips next to the VLSI chip and the empty sockets below the VLSI chips can be used at the same time, as they obviously share the space for the parity RAM.

The big array of sockets with the four chips inserted is obviously prepared to take physically bigger chips as a second option. This would still be chips with one bit per chip, but more address lines. The only common RAM type that matches this description is a chips with 1M of storage locations, 1 bit each, called "1M x 1" chips. Those chips are DIP18 chips and would fit into the longer part of the 36 sockets. So I am very confident that yanking all the memory chips from the board, and filling the big array sockets with 1M x 1 chips (google for "1M x 1 DRAM DIP" to find sellers; your current chips have an access time of 70ns, as indicated by the -7 suffix, so to match speed, you need to buy the 70ns or 60ns version). It is also quite likely that the eight 20-pin 256K x 4 chips would be replaceable by 1M x 4 chips. Both of these chip types have the same DIP 20 case. You can probe whether 1Mx4 chips are going to work by checking continuity between pin 5 of the x4 sockets and pin 15 of the long part of the x1 sockets, as shown in the picture below. If this is the case, you can combine 8 chips of 1M x 4 DRAM in the sockets that currently have 8 chips of 256k x 4 DRAM with 4 chips of 1M x 1 DRAM in the sockets overlapping the sockets that currently have 256k x 1 DRAM installed.

I also see further empty sockets below the area you photographed, labelled "bank 1". As this area is incomplete, I can't guess how those sockets are to be used, and whether they can be used at the same time as the sockets that currently are in use.

canthearu wrote on 2021-06-04, 05:19:

You should be able to get 4Meg probably, maybe 5meg including what is already there.

How much memory does it currently show when you boot up? It should show up as 1meg given the numbers on the chips in the top bank of 8 chips.

It shows 1024MB

metrox wrote on 2021-06-04, 05:44:

canthearu wrote on 2021-06-04, 05:19:

You should be able to get 4Meg probably, maybe 5meg including what is already there.

How much memory does it currently show when you boot up? It should show up as 1meg given the numbers on the chips in the top bank of 8 chips.

It shows 1024MB

If it does, the BIOS is buggy. It should show up at 1024KB, not 1024MB. There is no way a consumer-grade computer of that time having 1 gigabyte of RAM...

mkarcher wrote on 2021-06-04, 06:19:

If it does, the BIOS is buggy. It should show up at 1024KB, not 1024MB. There is no way a consumer-grade computer of that time having 1 gigabyte of RAM...

Ok, Mr Pedantic.

Of course it would only be should 1024 KB. The 286 processor only has 16 MiB of address space.

But yes, you are likely right about the memory support. 4Meg seems to be an upper reasonable limit for a lot of these older 286 boards.

4MB is the limit for onboard memory, but you can likely still get the full 16MB by using expansion cards on the ISA bus.

Is there any markings/brand on the board? That way we could try and find settings and specifications for it.

That VLSI chipset is well documented, full datasheets are available at a quick google.

Max onboard RAM is 4MB as others have said

Looks like this one, http://www.win3x.org/uh19/motherboard/show/5160 there's some DRAM config info in the jumper manual.

BitWrangler wrote on 2021-06-04, 16:43:

Looks like this one, http://www.win3x.org/uh19/motherboard/show/5160 there's some DRAM config info in the jumper manual.

The TH99/UH19 description is slightly misleading by using the terms "bank0" till "bank3", although the board only has two banks. Bank 0 and bank 2 are the same memory bank, but in a different format for different chip types. The same applies to bank 1/bank 3. It's notable that the manual doesn't list the possibility of installing 1Mx4 chips (514400). Maybe those chips (4MBit memory chips) weren't available yet, or the board indeed doesn't support them. The continuity check I suggested above gives an indication whether the design is prepared for those chips.

canthearu wrote on 2021-06-04, 06:27:

Ok, Mr Pedantic. […]
Show full quote

mkarcher wrote on 2021-06-04, 06:19:

If it does, the BIOS is buggy. It should show up at 1024KB, not 1024MB. There is no way a consumer-grade computer of that time having 1 gigabyte of RAM...

Ok, Mr Pedantic.

Of course it would only be should 1024 KB. The 286 processor only has 16 MiB of address space.

But yes, you are likely right about the memory support. 4Meg seems to be an upper reasonable limit for a lot of these older 286 boards.

Apologies it read 1024KB.

I was thinking getting this "Lot of 4 Intel P21014-10 IC Fast Page DRAM 256Kx4"

https://www.ebay.com/itm/333637747128?hash=it … fsAAOSwlDBddv3U

This is the motherboard.

https://stason.org/TULARC/pc/motherboards/B/B … N-286-MB-3.html

metrox wrote on 2021-06-08, 01:48:

I was thinking getting this "Lot of 4 Intel P21014-10 IC Fast Page DRAM 256Kx4" […]
Show full quote

I was thinking getting this "Lot of 4 Intel P21014-10 IC Fast Page DRAM 256Kx4"

https://www.ebay.com/itm/333637747128?hash=it … fsAAOSwlDBddv3U

This is the motherboard.

https://stason.org/TULARC/pc/motherboards/B/B … N-286-MB-3.html

That won't help you. The two banks you have that can take 256kx4 DRAM chips are already fully populated. As per the first pic you posted, you can't add more.

If you want to go past 1MB total RAM, you need to get 1Mx1 DRAM chips. Nine of them per MB - so 18 if you want to go to 2MB or 36 if you want to go to 4MB

maxtherabbit wrote on 2021-06-08, 01:53:

metrox wrote on 2021-06-08, 01:48:

I was thinking getting this "Lot of 4 Intel P21014-10 IC Fast Page DRAM 256Kx4" […]
Show full quote

I was thinking getting this "Lot of 4 Intel P21014-10 IC Fast Page DRAM 256Kx4"

https://www.ebay.com/itm/333637747128?hash=it … fsAAOSwlDBddv3U

This is the motherboard.

https://stason.org/TULARC/pc/motherboards/B/B … N-286-MB-3.html

That won't help you. The two banks you have that can take 256kx4 DRAM chips are already fully populated. As per the first pic you posted, you can't add more.

If you want to go past 1MB total RAM, you need to get 1Mx1 DRAM chips. Nine of them per MB - so 18 if you want to go to 2MB or 36 if you want to go to 4MB

Will these work then? https://www.ebay.com/itm/323774437581?epid=13 … zEAAOSwj~Jcr27w

metrox wrote on 2021-06-08, 02:02:

maxtherabbit wrote on 2021-06-08, 01:53:

metrox wrote on 2021-06-08, 01:48:

I was thinking getting this "Lot of 4 Intel P21014-10 IC Fast Page DRAM 256Kx4" […]
Show full quote

I was thinking getting this "Lot of 4 Intel P21014-10 IC Fast Page DRAM 256Kx4"

https://www.ebay.com/itm/333637747128?hash=it … fsAAOSwlDBddv3U

This is the motherboard.

https://stason.org/TULARC/pc/motherboards/B/B … N-286-MB-3.html

That won't help you. The two banks you have that can take 256kx4 DRAM chips are already fully populated. As per the first pic you posted, you can't add more.

If you want to go past 1MB total RAM, you need to get 1Mx1 DRAM chips. Nine of them per MB - so 18 if you want to go to 2MB or 36 if you want to go to 4MB

Will these work then? https://www.ebay.com/itm/323774437581?epid=13 … zEAAOSwj~Jcr27w

🤣

You're getting warmer but, no

Look at the chips - those are SOJ package, you need DIP. There is no way to physically interface them to your board unless you fabricate some type of adapter

Sadly finding DIP package 1Mx1 at a reasonable price these days is no easy task. You might just want to consider sticking with what you have. 1MB is honestly adequate for a 286 system, especially considering your chipset doesn't support shadow RAM or EMS anyway. The better move might be adding a ISA memory card if you really need more RAM for Windows 3.x or something

I second that.

As a "cheap" starter kit, I think the 1MB RAM card from Lo-Tech (or from other makers) is worth a look.

It's merely an 8-Bit UMB RAM card, though.
So it's a little bit of a performance bottle-neck..

Nevertheless, it maybe can be helpful to get DOS and drivers out of conventional memory.

The remaining RAM then can be used for applications.

That being said, I don't know how exactly the board does organize memory.

Depending on how it does, some RAM might be available above 1MB for Extended Memory.
That would be good for XMS/Himem.sys.

Edit: Personally, I had a good experience with 286 PCs that had 4MB RAM (total).
That was fine for loading Windows, EMM286, disk cache etc.
So I *guess* that 2MB (total) may also do. Or ~1MB of free, unused RAM.

With less available memory, there might be resource conflicts.
Because contiguous memory is needed or prefered by some more sophisticated applications.
Programs using overlay files (.OVL) may also need or favor such memory.

Jo22 wrote on 2021-06-08, 04:49:

I second that. […]
Show full quote

I second that.

As a "cheap" starter kit, I think the 1MB RAM card from Lo-Tech (or from other makers) is worth a look.

It's merely an 8-Bit UMB RAM card, though.
So it's a little bit of a performance bottle-neck..

Nevertheless, it maybe can be helpful to get DOS and drivers out of conventional memory.

The remaining RAM then can be used for applications.

That being said, I don't know how exactly the board does organize memory.

Depending on how it does, some RAM might be available above 1MB for Extended Memory.
That would be good for XMS/Himem.sys.

Edit: Personally, I had a good experience with 286 PCs that had 4MB RAM (total).
That was fine for loading Windows, EMM286, disk cache etc.
So I *guess* that 2MB (total) may also do. Or ~1MB of free, unused RAM.

With less available memory, there might be resource conflicts.
Because contiguous memory is needed or prefered by some more sophisticated applications.
Programs using overlay files (.OVL) may also need or favor such memory.

8-bit memory on a 286 system is a massive bottleneck, and that card would really be a colossal waste anyway as all it would gain him is 96kB of UMB (assuming a VGA system) because the E-region is wire-mapped to mirror the system ROM on that board

HIMEM can already be used as is, since the board is mapping 384kB to extended memory. This will provide for the 64kB HMA to load DOS into as well as having some XMS left over for programs. Free conventional memory shouldn't be an issue with DOS loaded high.

If more XMS/EMS is required, a 16-bit ISA board should be purchased. Intel Above Board, AST Rampage, BocaRAM, etc.

Oh, come on, let's relax. 😁

I mentioned it, because that board is at least available.
And slow RAM is better than no RAM at all.
- Personally, I could live with that speed penalty (I've got another UMB catd for testing) also.

BocaRAM,AST Rampage and so on are either rare or expensive.

Anyway, Lo-Tech also has (had) a 2MB EMS card.
While EMS is not as useful as XMS anymore, it's still nice to have.

And yes, that card is 8-Bit again. But so are several ancient 16-Bit ISA EMS boards, too.
They have a 16-Bit connector, but the actual transfer on some of them is done in 8-Bits.

A few games can use EMS, Windows 3.0 in Real-Mode can..

Edit: Couldn't the 1MB card be configured for the 0-640KB range, too?
If the 286 chipset does have at least a little bit of intelligence,
it should be able to start with its first 640KBs of memory beyond 1MB.