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V-tech laser XT/3 1664KB of memory, how to acess the extra 1MB EMS motherboard memory

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Robin4

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Hi all

I have here a V-tech laser 8086 10Mhz XT/3 computer which had the full 640KB of conventional memory. There is an option to add memory chips to the motherboard and should give the system about 1MB of EMS memory.
Does anybody knows how to access it, and when a driver is need.. Which factory driver do i need to use? And which lines do i have to setup in autoexec.bat and config.sys..

My system should be comparible with a Laser Turbo XT..
 
Expanded memory on the VTech Laser XT/3 is covered on pages 58 to 60 of the computer's operations manual, at [here].
Page 60 answers your questions.
 
Iam back to this topic.

Like to know if its really worth to use the onboard 1MB of expended memory (memory chips already have for expended option) , or am i maybe better of to disable that feature and just going with a 2MB EMS card ISA instead?
 
What are you planning on running? Back when I had an EMS card, I found it challenging to use more than 512K of EMS for applications unless I had multiple applications under Desqview which could easily need more than even the 2 MB under consideration.

What capacity is the hard drive? 512 kB of EMS for disk cache could handle any FAT-16 drive with a very good read ahead. Try it with 1 MB and consider buying a card only if you start noticing memory starvation.
 
I built a homemade memory card for my Tandy 1000s that gives them a meg of EMS RAM (software compatible with the lo-tech 2MB EMS card), and honestly I’ve had to work pretty hard to find *any* software apropos for XT class computers that really needs it. It’s pretty much there for bragging rights.

Re: using it as a disk cache, there might be use for that if you have the original spinning rust, but if you’re using an XT-CF, forget it. I’ve benchmarked my XT-CF against a *ramdisk* running in EMS and they’re almost the same. On an XT the CPU/bus speed is the pretty much the limiter once you eliminate physical seek time.
 
I built an EMS card to run Master of Orion on a 286/12. Then I learned that it works well, but isn't particularly enjoyable at that speed.
There are some other games which can use EMS if available, but don't require it. Not sure whether these are usable on an XT though.
 
krebizfan said:
What are you planning on running? Back when I had an EMS card, I found it challenging to use more than 512K of EMS for applications unless I had multiple applications under Desqview which could easily need more than even the 2 MB under consideration.

What capacity is the hard drive? 512 kB of EMS for disk cache could handle any FAT-16 drive with a very good read ahead. Try it with 1 MB and consider buying a card only if you start noticing memory starvation.
Click to expand...

1. Should be handy for the printer spooler.
2. Dont know if it can be used as a floppy copy disk buffer?
3. Maybe programs that can use EMS ? (maybe windows 3.0 if possible)

I dont going to use an ISA EMS card, when i dont have enough ISA slots on the motherboard.. Then will choose for the EMS Memory on the motherboard instead, if i can get it running.
 
Robin4 said:
1. Should be handy for the printer spooler.
2. Dont know if it can be used as a floppy copy disk buffer?
3. Maybe programs that can use EMS ? (maybe windows 3.0 if possible)

I dont going to use an ISA EMS card, when i dont have enough ISA slots on the motherboard.. Then will choose for the EMS Memory on the motherboard instead, if i can get it running.
Click to expand...
There were print spoolers that used EMS which is better than leaving the memory unused.
I think some of the third party copy routines could use EMS and a RAMDISK could be used as an intermediary. Just do not use the DOS 4 expanded memory buffer routines.
Windows 3 does not use EMS except in virtual DOS machines which need a 386. Windows 2 will use EMS but that is a very complicated issue that generally requires trying to run multiple large applications at the same.
Giant spreadsheets were the primary use case for EMS at the time but current hardware would be so much faster that there isn't much point.
 
krebizfan said:
Windows 2 will use EMS but that is a very complicated issue that generally requires trying to run multiple large applications at the same.
Click to expand...

Windows 2.x EMS is a gigantic can of worms. The TL;DR as I vaguely understand it is unless you have EMS 4.0 with “large page support” (which is a fairly exotic requirement; simple cards like the lo-tech won’t do) it can only use EMS for data, not program code.

Later versions of PC-GEOS can make some use of it and perform a million times better than Windows on XTs so if you really want a GUI environment that’s the way to go but, honestly… why?
 
Windows 2 with EMS 4 cards could move code segments into EMS if there were page frames not used for data available. In practice, little more than the Clock executable could be shoved into EMS since one seldom had two 64K sets of page frames and many code segments were bigger than the page frame to be used.
Large page frames were about 300-400 k of low memory that was moved as a unit. Good for applications with multiple locked segments like DOS applications or large Windows applications. This was very similar to the multi-tasking mode used by Desqview.
EMS was horrible. Protected mode simplified everything.
 
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