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Ryan Hefferan
February 3rd, 2014, 07:19 PM
I recently bought an above board ps/pc which thank god works.
My xt clone already has 640kb installed, when i plugged it in and turned it on, it dropped to 512Kb inline with the switches for 512kb conventional memory address.

i changed the switches to reflect a conventional memory address of "none". Is that correct? when i plugged it back in i had my 640kb back.

Bank 0 and 5 appear to be unpopulated, and with 1 -4 populated by that that appears to be a invalid configuration.

Banks 1 through 4 appear to be populated with 256kb chips. The switch setting supports this, as it is set for 256kb chip type. Although it appears they are two different types of 256kb chips. (HM50256P-15 U100533, HM50256P-15 U1005NN). It looks like as above i should reseat bank 4 to bank 0. Correct?

Jumper swtiches for reference:

http://webcache.googleusercontent.com/search?q=cache:http://stason.org/TULARC/pc/io-cards/I-L/INTEL-CORPORATION-Multi-I-O-card-ABOVE-BOARD-PS.html#.UvBko_mSyT8

modem7
February 5th, 2014, 12:18 PM
Let's go back a step.

0 to 640 KB: Conventional memory.
640 KB to 1 MB: The window to any expanded memory will reside in here.
1 MB onwards: Extended memory. Not available in 8088 based computers such as XT clones.

In your XT clone, the only memory types you can use are conventional memory and expanded memory.

Your conventional memory is already at the limit of 640 KB.

That means that expanded memory is the only memory you can add, but before you add that, perhaps you should be asking yourself, "Do I have any programs that can use expanded memory?"
For a list of such programs, see the earlier thread [here (http://www.vintage-computer.com/vcforum/archive/index.php/t-28574.html)].


Bank 0 and 5 appear to be unpopulated, and with 1 -4 populated by that that appears to be a invalid configuration.
Yes. Invalid per the information you pointed to.


It looks like as above i should reseat bank 4 to bank 0. Correct?
Yes. Move bank 4 chips into bank 0.

Ryan Hefferan
February 5th, 2014, 12:39 PM
Thanks for the confirmation. It's been so long since i've worked with hardware this old.

My little pet project is getting a game called nethack running on it.

Earlier versions were small enough to fit in conventional memory, but later versions such as 3.2 ~, according to the source files, are too big for conventional memory if you compile with all features enabled. However, if you have expanded memory, you can compile with a overlay which will use expanded memory.

Trixter
February 6th, 2014, 10:30 AM
Earlier versions were small enough to fit in conventional memory, but later versions such as 3.2 ~, according to the source files, are too big for conventional memory if you compile with all features enabled. However, if you have expanded memory, you can compile with a overlay which will use expanded memory.

You don't need expanded memory to use programs with overlays; most overlay systems will page code in from disk when needed. (There is a speed penalty for this, of course, so I'm not trying to dissuade you from getting your AboveBoard working since it will eliminate repeated disk access while playing. I'm mentioning it so that you can release your work so that we can all give nethack a try on our 16bit DOS systems.) :-)

Ryan Hefferan
February 6th, 2014, 01:10 PM
The great news is the overlay used for the game is a custom one by the developers, so the one overlaid binary will use EMS if its there, disk if not. I just spent hours tracking down a copy of microsoft C 5.0 AND 6.0A, as well as NDMAKE. (If anyone needs these, please contact me.) The developers state that its incompatible with the freely avaliable borland C, so tracking down microsoft C was a pain. (Well it is 24 years old i guess....)

In any event, i suspect i'll start a new thread in regards to this ongoing effort