Dos games and 16mb of ram

Basic HIMEM.SYS recognizes only 64MB of RAM. Enhanced extended memory managers can recognize more than that if installed.

I have played DOS games in my Pentium I and II machines with multi-configurations -128MB, 256 and 512MB RAMs. I didn't face any problems.

Once, I noted when I tried playing Crusader No: Regret in a Slot 1-based PIII 450 CPU with 256MB RAM on a DFI P2XBL motherboard, the game wouldn't load until I decreased the available RAM by allocating a major chunk of it to a RAMDISK using XMSDSK program, leaving about 128MB total RAM free.
But this can be an isolated incident, since when I tried again in other systems with 256 and 512MB RAM, the game just runs fine.

I usually install more RAM (just because I have quite a number of "sticks" lying around) and allocate excess RAM to a RAMDISK and setting the SET TEMP= to the ramdisk in DOS, and let Windows 95/98 utilize as much as it can for itself in my Pentium machines.

I also had 128MB of RAM on various test-bench configurations and most games will work just fine. Some don't and there are workarounds as discussed in the thread linked by F2bnp.

CU_AMiGA wrote:

Hi

I want to get to the bottom of this once and for all! I've heard problems with DOS games working with machines equipped with more than 64MB RAM. IE Games not running or running slower. Is this actually true? My PentiumMMX machine is currently equipped with 64MB RAM but i do have more RAM at home. But i want to get to the bottom of this before i do anything! Any?

Thanks for your time.

In a word; yes its true.

#1: for all intents and purposes dos cannot access more than 64mb of ram. Having more will just sit idle.

#2: never install more than 64MB of ram in a Pentium 1 (socket 5 or 7) motherboard unless you are CERTAIN that the board can cache the extra memory. Rule of thumb; if you don't know for sure it doesn't.

#3: same rule applies for super 7 (amd k6) and slot 1. however the limits are 256mb and 512mb respectfully.

more detailed information about #2 can be had here: http://www.pcguide.com/ref/mbsys/cache/charCa … eability-c.html

luckybob wrote:

#2: never install more than 64MB of ram in a Pentium 1 (socket 5 or 7) motherboard unless you are CERTAIN that the board can cache the extra memory. Rule of thumb; if you don't know for sure it doesn't.

Just wanted to add that the 430HX chipset supports up to 512MB cacheable RAM. Installing a AMD K6-2+ or AMD K6-III with built-in L2 cache also removes the 64MB limit on the other chipsets.

If everything fails installing an SSD for use as disk cache negates any performance loss.

Those are rather special instances. My rule applies, you are just making sure the ram is cache-able by using proper parts. also, on the 430hx, >64mb cache was OPTIONAL. The only HX boards i've seen that have this enabled are the server/workstation class boards.

luckybob wrote:

Those are rather special instances. My rule applies, you are just making sure the ram is cache-able by using proper parts. also, on the 430hx, >64mb cache was OPTIONAL. The only HX boards i've seen that have this enabled are the server/workstation class boards.

I agree that it is a generally good rule to go by. Only on server/workstation boards? My Gigabyte 586HX which is a normal AT board has 512MB cache support. I haven't seen many other HX boards so you might be right that it is uncommon. The Gigabyte board requires an additional tag-ram chip to be installed to activate it.

I remember one game did not work with 64MB installed. I recall the game determined the total memory amount in kilobytes, and 65536 kilobytes does not fit into 16-bit unsigned integer and the game said there is 0 kilobytes of memory.

I recall the game was called Alien Incident and I don't recall what did I do to make it work. I still have the original box though.