Since when has UMBs been a thing for 8088/286's?

Never saw anything like that back in the old days when these machines were current. 4meg of ram was a luxury for a 286 machine (1meg was more common) and shadow memory also didn't really become a thing until 386s. You would be lucky to have a MFM hard drive or a really small IDE hard drive, so you didn't have to go constantly swap floppies like I had to for many a year!

Just seems to be strange to get so hung up on these exotic features. The fact that people have a 30 year old motherboard that still boots and works is a marvel to begin with!

Edit: Now get off my lawn so I can walk uphill to school both ways through 6 feet of snow and a -50 degree wind blast!

Hm. Since the late 80s/ early 90s? Not sure. 🤷‍♂️
Back then, DOS memory was most precious.

I do have a DIY UMB card from c't magazine.
It's about the size of an AdLib card and has a PC/XT bus connector.
The PCB was printed in the magazine foe etching at home.
The UMB card consists of several 80s era ICs.

Also, there are documents from the 80s that explain how to upgrade an IBM PC to 704KB or more.
An utility for that was made in the 80s, too.

Some PC emulators from the 1980s also had support for more than 640KB.

Some pictures in my old thread over here:
80x86/Vxx PC emulators with x87, EMS, UMBs and no artificial 640KiB limit ?

- By the way, perhaps I was a bit to harsh in that old thread. My apologies for that. 😔

Edit: You may think that 4MB were luxury for a 286.. I can understand that.
However, it's no luxury for Windows 3.1x.
With just a meager Megabyte, Windows will run out of memory quickly.
You can barely do anything with that. I know, because I tried.
Running Visual Basic or any other development system will be next to impossible.
Same with playing MOD files on DOS. Many modules don't fit into memory.

1MB was the norm for a 286 PC, yes, but it never was appropriate and it was also heavily criticized even back in the day.
Magazines wrote how the 286 PC never could use its full potential because of both physical memory limitations and segmentation.
Magazines essentially wrote that 286 PCs were mistreated as fast IBM PCs merely during their lifetime.

Jo22 wrote on 2022-06-16, 12:40:

- By the way, perhaps I was a bit to harsh in that old thread. My apologies for that. 😔

And I was definitely being too old and grumpity. Hence for my edit to add humor!

It just seemed back in the actual day, things like EMS, UMB and shadow memory didn't actually exist for us until the 386 came out and could do it through EMM386.EXE and through the 386 chipsets. And at that stage, you would see 50 trident 9000i cards for every good ET4000 and maybe 10 x ET4000s for each GUI accelerated ISA card. Then TIGA was simply a dream, and you only ever knew it existed because WINTACH had the benchmarks for these cards included in the results.

I bit like MT32 or SC55 in those days was simply an option in the setup for some games, I didn't even realize they were external Midi modules until some years later.

Still, I think the most awesome waste of my RA50 (MT-32 synth in an arranger) lately is spending some hours playing Klondike via Sierra's Hoyles book of games on it. Of all the amazing things the MT-32 synth can offer, it is hilarious to use it just to listen to cards shuffle (in stereo mind you) and have the computer make bings when you stack cards!

As for the OP, I too have a soft spot for 286 12mhz computers ... it was my first system past the 8088, and I ended up making it work with my own work or money, back when buying a 3.5 inch floppy drive was a thing (I think I paid $60 AU for it back then in the early 90's) and you simply didn't fall over stacks of them. My 286 isn't nearly as fancy, with:

286-12mhz
No co-processor.
4meg ram
NE2000 clone ethernet card with XT-IDE Bios.
250gb hard drive (because they are quiet and I had lots)
Oak 067 512KB video card
Sound blaster 2.0 card (this was my original card, I gave it away many years ago and the kind soul ended up giving it back many years later) with newly added CMS chips.
3.5 inch 1.44meg drive
5.25 inch 1.22meg drive

Still fancier than what I grew up with by a long shot!

Jo22 wrote on 2022-06-16, 12:40:

Edit: You may think that 4MB were luxury for a 286.. I can understand that. However, it's no luxury for Windows 3.1x. With just […]
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Edit: You may think that 4MB were luxury for a 286.. I can understand that.
However, it's no luxury for Windows 3.1x.
With just a meager Megabyte, Windows will run out of memory quickly.
You can barely do anything with that. I know, because I tried.
Running Visual Basic or any other development system will be next to impossible.
Same with playing MOD files on DOS. Many modules don't fit into memory.

Yep, I know that for sure.

I spend quite some time with a 386-DX25 with 2meg ram and a 40mb MFM drive.

I become very familiar with swapping in 386 enchanced mode. All on a Hercules Monochrome monitor.

For most 286 builds EMS is more useful than UMB. There simply aren't that many device drivers and TSRs you really need to be loading, and you can use the HMA to load DOS high, providing enough conventional free to run most anything.

appiah4 wrote on 2022-06-16, 09:22:

simon_e_hall wrote on 2022-06-16, 08:52:

pshipkov wrote on 2022-06-16, 05:55:

@appiah4 Hope my words didn't offend the poor mobo. They were mostly a joke. 286 PCBs with integrated IDE/FDD are not that rare […]
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@appiah4
Hope my words didn't offend the poor mobo. They were mostly a joke.
286 PCBs with integrated IDE/FDD are not that rare but always cool indeed.
The serious side of my message was that all 286/386 Headland chipsets are not great in general.

---

Having hard time following the conversation about the RAM card.
What is the point of bothering with that if there are 16Mb of on-board RAM ?

Essentially the HT18 chipset can do EMS, so removed the ram card.

But they can't do EMS and UMb at the same time, can they? I believe @HamJammer had a few videos about this.

It is working at the moment, not perfect have both working at the same time, need to do more optimization and testing through.

simon_e_hall wrote on 2022-06-16, 15:24:

It is working at the moment, not perfect have both working at the same time, need to do more optimization and testing through.

How much memory do you currently have installed on the 286 HT18C board ?

Well another curve ball, whatever CD driver I use with the EMS driver installed for some reason hangs the system, double checked for conflicts but could not find any, throught it might be the Promise EIDE Pro so swapped that out for a generic controller card and still the same issues. So then I decided to install a SCSI CD ROM and see if it happens with that and no it does not, wasn't really a fan of the EIDE Pro in this build.

So another change to the build Promise EIDE Pro out, AHA 1542CF in including SCSI hard and CD drive, then a generic controller card for serial ports, etc. including keeping one IDE channel enabled to allow using CF cards for experimenting with different operating systems and data transfer.

weedeewee wrote on 2022-06-16, 17:10:

simon_e_hall wrote on 2022-06-16, 15:24:

It is working at the moment, not perfect have both working at the same time, need to do more optimization and testing through.

How much memory do you currently have installed on the 286 HT18C board ?

16mb simm
1mb dram

canthearu wrote on 2022-06-16, 12:12:

Since when has UMBs been a thing for 8088/286's? […]
Show full quote

Since when has UMBs been a thing for 8088/286's?

Never saw anything like that back in the old days when these machines were current. 4meg of ram was a luxury for a 286 machine (1meg was more common) and shadow memory also didn't really become a thing until 386s. You would be lucky to have a MFM hard drive or a really small IDE hard drive, so you didn't have to go constantly swap floppies like I had to for many a year!

Just seems to be strange to get so hung up on these exotic features. The fact that people have a 30 year old motherboard that still boots and works is a marvel to begin with!

Edit: Now get off my lawn so I can walk uphill to school both ways through 6 feet of snow and a -50 degree wind blast!

It wasn't really pure UMB but remember buying a 286 memory manger that could do the same thing loading programs into upper memory. Cannot remember what it was called, it came on a 5.25" floppy and was especially for the 286 with C&T chip sets like Zenith's did at the time. Picked it up cheap in a 2nd hand computer shop and still have it somewhere, another reason why I like it is that is stamped all over with labels stating it is not for export outside the United States, picked it up in the UK! That was around 92 maybe.

simon_e_hall wrote on 2022-06-16, 17:21:

weedeewee wrote on 2022-06-16, 17:10:

simon_e_hall wrote on 2022-06-16, 15:24:

It is working at the moment, not perfect have both working at the same time, need to do more optimization and testing through.

How much memory do you currently have installed on the 286 HT18C board ?

16mb simm
1mb dram

? do you mean you have the simm sockets and the dip sockets populated ?
max addressable space for a 286 is only 16MB.

Wonder if the e0000 region being unusable is due to the EMS being available or due to being reserved by the BIOS. (wouldn't be surprised if it's both) That would mean someone should re the bios and figure out some chipset settings since I don't think a datasheet is available for the HT18C chipset.
enjoy !

ps. QRAM is a well known memory manager.

Definitely everything is populated and brought on line bit by bit, dram only, then first two simms, then last two simms, booting in between, is it possible it is just not reading the last simm module fully?

It's somewhat common for 286 builds not making the E region accessible due to the fact the AT had it mapped to ROM sockets on the system board

simon_e_hall wrote on 2022-06-16, 17:45:

Definitely everything is populated and brought on line bit by bit, dram only, then first two simms, then last two simms, booting in between, is it possible it is just not reading the last simm module fully?

I'd say it's more likely that the 1MB dram in the dip sockets is overlapping with two of the simms.
The board should still work with 16MB simms without the 1MB dip drams installed.

maxtherabbit wrote on 2022-06-16, 17:56:

It's somewhat common for 286 builds not making the E region accessible due to the fact the AT had it mapped to ROM sockets on the system board

Excellent, answers that mystery thank you, never seen that before.

simon_e_hall wrote on 2022-06-14, 17:50:

Amazing to see the interest this has caused, thought it would be a rather low-key build.

I am enjoying your thread on the 286. You guys are using terms that I don't know but I'm still finding it very interesting. I've never been a from-scratch builder and all my systems have come from hand-me-downs or the dump/junk/scrap yards.

My start in computers was with a NorthStar Advantage and CP/M. The first computer I bought for myself was similar to the Zenith you showed. It was a Tandy 1400FD running DOS 3.3. It had a CGA external port so I ended up getting a Goldstar CGA monitor for it. But we liked the blue LCD screen better!

My FIL had an IBM PC 5150. And we upgraded to Hercules. But it was mostly about business use with R:Base and Professional Write and DAC Easy. But at night we played games like Wheel of Fortune, Jeopardy, and Press Your Luck on the Hercules green screen. I played Cribbage Partner on my Tandy 1400FD PC.

When we upgrade we went directly to a Micron Pentium 75. I was given an AST Premium Cupid 486-33. I never had a 286 in those days.

Now I have two working 286 machines in my collection. An IBM XT-286 running PC DOS 3.3 and a KLH 286-12 running DR-DOS 7.03. No Windows on these machines. I have two more 286s on my bench ready for cleanup. I have confirmed they both power up but have not completed the refurbish yet. One is a NEC Powermate 286 with only one floppy. The other is branded as a MicroLab 286, it has one 3.5" floppy, one 5.25" floppy, and a hard drive.

I'll be following along as you finish your 286 build.

Seaken64

Well had the soldering iron out, two sockets for the oscillators installed.

On the board:
Oscillator 2 is the primary.
Oscillator 3 is the secondary

Oscillator 1 is next to the 287 not put a socket in that yet, just ordered some more

So with a 50mhz Oscillator in landmark scores are:

CPU: 33.76
FPU: 33.51
Video: 7992.20
Now reaching 8.8fps (3D bench v1.0)

Edit: previously

CPU: 29.73
FPU: 28.38
Video: 6342.18
in landmark
And 7fps

Of note the secondary Oscillator will not run the system by itself, the primary must be populated.

seaken64 wrote on 2022-06-16, 22:34:

I am enjoying your thread on the 286. You guys are using terms that I don't know but I'm still finding it very interesting. I've […]
Show full quote

simon_e_hall wrote on 2022-06-14, 17:50:

Amazing to see the interest this has caused, thought it would be a rather low-key build.

I am enjoying your thread on the 286. You guys are using terms that I don't know but I'm still finding it very interesting. I've never been a from-scratch builder and all my systems have come from hand-me-downs or the dump/junk/scrap yards.

My start in computers was with a NorthStar Advantage and CP/M. The first computer I bought for myself was similar to the Zenith you showed. It was a Tandy 1400FD running DOS 3.3. It had a CGA external port so I ended up getting a Goldstar CGA monitor for it. But we liked the blue LCD screen better!

My FIL had an IBM PC 5150. And we upgraded to Hercules. But it was mostly about business use with R:Base and Professional Write and DAC Easy. But at night we played games like Wheel of Fortune, Jeopardy, and Press Your Luck on the Hercules green screen. I played Cribbage Partner on my Tandy 1400FD PC.

When we upgrade we went directly to a Micron Pentium 75. I was given an AST Premium Cupid 486-33. I never had a 286 in those days.

Now I have two working 286 machines in my collection. An IBM XT-286 running PC DOS 3.3 and a KLH 286-12 running DR-DOS 7.03. No Windows on these machines. I have two more 286s on my bench ready for cleanup. I have confirmed they both power up but have not completed the refurbish yet. One is a NEC Powermate 286 with only one floppy. The other is branded as a MicroLab 286, it has one 3.5" floppy, one 5.25" floppy, and a hard drive.

I'll be following along as you finish your 286 build.

Seaken64

Welcome!

Any idea what the secondary oscillator is used for?

Anonymous Coward wrote on 2022-06-17, 23:43:

Any idea what the secondary oscillator is used for?

The ISA bus and or the KBC