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Question(s) about EMS

luckybob

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Last week or so I lost an ebay auction that included an 8 bit EMS board and no less than 3 8-bit scsi cards, with 2 hard-card's. I was going for the scsi cards, but I can't help but wonder, Just how useful is EMS, in 808X computer?

I understand the mechanics of EMS,XMS ram. My goal with my model 25 will be pre-vga gaming with a smattering of screwing around in IRC and the occasional network file transfer. (i'm planning on using a parallel<> Ethernet adapter) I was wondering just how much you can use EMS for. Can I put dos/drivers/etc into EMS? Basically freeing up as much of that 640k as possible. While on the subject, are there any pre-vga games that can utilize EMS? If I recall, Wolfenstein could, but it maybe a bad brain cell pulling tricks on me.
 
I think there is no reason to use EMS/XMS on 8086/8088 based machine.
Most of 8086/8088 machine allows RAM with 640KB. (Tandy machine allows it to 768KB RAM)
I know 8086/8088 supports 1MB memory address. (Maybe 640KB is for RAM + 384KB is for BIOS, I/O port, H/W extension, etc.)
If you want to use EMS/XMS, CPU must be 80286 or higher.
80286 supports memory address to 16MB.
But I recoomend 80386 or higher to use it.
 
Last week or so I lost an ebay auction that included an 8 bit EMS board and no less than 3 8-bit scsi cards, with 2 hard-card's. I was going for the scsi cards, but I can't help but wonder, Just how useful is EMS, in 808X computer?

I understand the mechanics of EMS,XMS ram. My goal with my model 25 will be pre-vga gaming with a smattering of screwing around in IRC and the occasional network file transfer. (i'm planning on using a parallel<> Ethernet adapter) I was wondering just how much you can use EMS for. Can I put dos/drivers/etc into EMS? Basically freeing up as much of that 640k as possible. While on the subject, are there any pre-vga games that can utilize EMS? If I recall, Wolfenstein could, but it maybe a bad brain cell pulling tricks on me.

Since you are using a card, it will depend on the card's driver whether you will be able to load DOS drivers and things like file buffers into EMS. I cannot think of any pre-VGA game that supports EMS. Wolfenstein is not a pre-VGA game. Many VGA games that support EGA graphics do support or require EMS. I am not sure if a program like mTCP or the accompanying file transfer utility, for example, support EMS. EMS in the 1980s was mainly used for large spreadsheet and database programs.

Don't the Sierra SCI EGA games allow you to use EMS? That in itself is worth something.

No, they do not.
I think there is no reason to use EMS/XMS on 8086/8088 based machine.
Most of 8086/8088 machine allows RAM with 640KB. (Tandy machine allows it to 768KB RAM)
I know 8086/8088 supports 1MB memory address. (Maybe 640KB is for RAM + 384KB is for BIOS, I/O port, H/W extension, etc.)
If you want to use EMS/XMS, CPU must be 80286 or higher.
80286 supports memory address to 16MB.
But I recoomend 80386 or higher to use it.

Those Tandy computers that support 768K use the upper 128K strictly for video, so its really not Conventional Memory.

EMS works on an 8086 or 8088. XMS requires a 286 or greater.

A 386 is required to use a software Expanded Memory Manager like EMM386.EXE or QEMM. In an 8088, 8086 or 286, you must have an Expanded Memory Hardware board.
 
Since you are using a card, it will depend on the card's driver whether you will be able to load DOS drivers and things like file buffers into EMS.

You wouldn't happen to know which ones, would you? I watched an Intel board go bid-less on ebay so the seller might be willing to "bargain" now.
 
Don't forget the simple solution of putting a disk cache in EMS. With some games, setting up a RAMDISK for temporary files will also improve performance. CD-ROM drivers were frequently designed to use EMS.

EMS 4 or EEMS boards are needed to support any applications that can be (partially) loaded in EMS. Original EMS 3.2 cards will not do that. While it is not exact, nearly all EMS cards that used SIMMs were designed to support EMS 4; AST cards supported EEMS and then EMS 4. For an Intel card, you should be looking for one made in 1988 or later. EMS 4 standard dates from 1987 but I don't know exactly when Intel changed production over.

Most of the benefits for EMS come from either big applications like Lotus or multi-tasking environments like Windows or DesqView.
 
EMS is implemented as a relatively small window (or a few windows) that is mapped to the higher memory addresses - usually between 0C0000h and 0F0000h. This window can be scrolled across the entire EMS memory.

Generally EMS is designed for storing data and not for loading drivers (drivers require that memory will be always available in CPU address space). Yet it should be possible to map some EMS memory permanently, and use it as a UMB.

The UMB driver for XT mentioned above assumes that UMB memory is supported by the hardware and available when driver is loaded. So if somehow you'll configure EMS before loading the driver, it will be working.

If you're into electronic DIY, it is relatively simple to construct an ISA UMB memory card.
 
One game immediately comes to mind for EMS use -- Wing Commander. Did a hell of a lot less disk chugging as it pre-loaded as many assets as it could.
 
If you're running Microsoft networking on your 8086/8088 box, EMS 4.x can be pretty valuable. MSLANMAN moves about 300K worth of code into EMS. It leaves an 8086 system with some usable memory.
 
Last week or so I lost an ebay auction that included an 8 bit EMS board and no less than 3 8-bit scsi cards, with 2 hard-card's. I was going for the scsi cards, but I can't help but wonder, Just how useful is EMS, in 808X computer?

I understand the mechanics of EMS,XMS ram. My goal with my model 25 will be pre-vga gaming with a smattering of screwing around in IRC and the occasional network file transfer. (i'm planning on using a parallel<> Ethernet adapter) I was wondering just how much you can use EMS for. Can I put dos/drivers/etc into EMS? Basically freeing up as much of that 640k as possible. While on the subject, are there any pre-vga games that can utilize EMS? If I recall, Wolfenstein could, but it maybe a bad brain cell pulling tricks on me.

Was this it ???

http://www.ebay.com/itm/Vintage-IBM...B0JwrAROQjrZrlKU1TwVw%3D&orig_cvip=true&rt=nc
 
Sure was. I bid as much as my budget would allow. Were you the winner by chance?

Yes, by a Dollar. Actually my only and Max bid. What I was really after was the ST01 and ST-138. The other hardcard ended up being a RLL controller & drive. Don't need the Bocaram as my MOBO has sockets for it. Nor the modems or Ethernet cards. If you want the RAM card or any of the other stuff then perhaps we could work out a trade. The only dibs I am maintaining is on the st01 and drive.

Let me know.

Marc
 
Anyone know if anyone has looked into somehow opening up the last 128k of "lost" RAM in a PS/2 Model 25? Maybe you don't need to use an add-in-card at all if there is some way to mod the BIOS or memory mappings of the Model 25 to gain even a portion of that 128k for DOS, drivers, etc...

I have never looked into it, is it video ram, is it ROM address space, BIOS limit, or a portion of all three?

NOTE: this is all based on the 256k in DRAM chips on planar, and 2x 256k SIMMs, and unless I have lost my mind that equals 768k.
 
Anyone know if anyone has looked into somehow opening up the last 128k of "lost" RAM in a PS/2 Model 25? Maybe you don't need to use an add-in-card at all if there is some way to mod the BIOS or memory mappings of the Model 25 to gain even a portion of that 128k for DOS, drivers, etc...

I have never looked into it, is it video ram, is it ROM address space, BIOS limit, or a portion of all three?

NOTE: this is all based on the 256k in DRAM chips on planar, and 2x 256k SIMMs, and unless I have lost my mind that equals 768k.

The Model 25 isn't the only computer with this "lost" memory. The Applied Engineering PC Transporter XT-on-a-card for the Apple II also has 768k of RAM. I'm guessing its easier to keep the memory banks matched sizes then to have one 256k and the other 128k. That RAM can be accessed on that card though... on the Apple II side as a RAM disk.
 
The Model 25 isn't the only computer with this "lost" memory. The Applied Engineering PC Transporter XT-on-a-card for the Apple II also has 768k of RAM. I'm guessing its easier to keep the memory banks matched sizes then to have one 256k and the other 128k. That RAM can be accessed on that card though... on the Apple II side as a RAM disk.

Yeah, I have a PC Transporter too, I have wondered the same on that before too, but it bothered me less. I can make use of all 768k on the apple side, and I don't need as much on the PC side for network drivers and such like I do on my Model 25.
 
The PS/2 only has 640KB. There are two SIMM modules included, each provides nine 256kx1 bit chips, which gives 512KB plus parity. The optional sockets on board require two 64Kx4 plus two 64Kx1 for 128K plus parity.

The onboard MCGA graphics adapter has its own 64KB. A VGA upgrade disables the MCGA graphics chip and would overlap the RAM anyway.
 
The PS/2 only has 640KB. There are two SIMM modules included, each provides nine 256kx1 bit chips, which gives 512KB plus parity. The optional sockets on board require two 64Kx4 plus two 64Kx1 for 128K plus parity.

The onboard MCGA graphics adapter has its own 64KB. A VGA upgrade disables the MCGA graphics chip and would overlap the RAM anyway.

I believe this is correct, I can't pull up where I read that (naturally), but it seems right. However, I also remember seeing that if you add a memory card, it can backfill from that card into the 640-1m area. I should really find that again.
 
I believe this is correct, I can't pull up where I read that (naturally), but it seems right. However, I also remember seeing that if you add a memory card, it can backfill from that card into the 640-1m area. I should really find that again.

The first sentence is according to the technical reference for the machine, and I assume it would be correct. It also applies to the IBM PC XT/286 and probably the original PS/2 Model 30.
 
...The optional sockets on board require two 64Kx4 plus two 64Kx1 for 128K plus parity...

Interesting, I swear I read that it was 256K plus parity chips, I'm loosing it I guess, lol

Was just hoping for a way to get more RAM in mine without an ISA card, I need my SCSI card, and I really like having the NIC, but if I were to swap the NIC out, it would be for a sound blaster, not a RAM card.

Someone needs to make a XT-IDE, EMS/XMS, HD Floppy, Sound blaster/adlib combo card ;-)
 
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