After checking online, it does appear that there were some 120 MHz AMD 486 chips with write-through L1 cache, although from my experience, most 120 MHz AMD 486 chips were of the write-back variety. I do not have any comparative benchmarks for the 120 MHz write-thru chip. I do have benchmarks for the 100 MHz write-thru chip though.
Try setting your L2 cache to write-back. You should use the "engineer mode" to tighten up those cache timings. This will help quite a bit. You also want to tighten up your system memory timings.
If you are looking for a high-end 486, you might want to consider a CPU with 16 KB of write-back cache. Your CPU is 8 KB write-through. The AMD "5x86" 133 chip is 16 KB write-back and the majority of them will run at 160 MHz. If you want a fast 120 MHz system, you can consider one of the WB-enabled Intel DX4-100's or a Cyrix 5x86-100/120. All of the Intel 486 DX4's I've tested work well at 120 MHz. Many users have also had success with a Cyrix 5x86-100 at 120 MHz. For the WB-enabled Intel DX4's, look for an &EW on the face of the chip. If it has &E, those are write-through only.
Plan your life wisely, you'll be dead before you know it.
Try setting your L2 cache to write-back. You should use the "engineer mode" to tighten up those cache timings. This will help quite a bit. You also want to tighten up your system memory timings.
I tightend everything as low as it would go and set the DRAM speed from "slowest" to "fastest"
Seems to be much better now (amazing how much difference it made). Not sure if it is stable since I cannot boot an advanced OS right now
Norton systeminfo 8 is now 151
If you are looking for a high-end 486, you might want to consider a CPU with 16 KB of write-back cache. Your CPU is 8 KB write-through. The AMD "5x86" 133 chip is 16 KB write-back and the majority of them will run at 160 MHz. If you want a fast 120 MHz system, you can consider one of the WB-enabled Intel DX4-100's or a Cyrix 5x86-100/120. All of the Intel 486 DX4's I've tested work well at 120 MHz. Many users have also had success with a Cyrix 5x86-100 at 120 MHz. For the WB-enabled Intel DX4's, look for an &EW on the face of the chip. If it has &E, those are write-through only.
Your speedsys score has improved some, however I estimate it should be closer to 45. From my benchmark spreadsheet, I do not see any difference in the Speedsys "score" from write-back to write-through on AMD 486 chips. Your L1 speed should be around 80 MB/s, L2 around 56 MB/s, and memory throughput around 44 MB/s. These are results from a UMC 8881/8886 chipset-based motherboard, however I have found them to be fairly consistent among other UMC 8881/8886-based motherboards. I see you are using a SiS 496/497-based motherboard. These motherboards typically perform a little better than the UMC results for memory throughput, however they have about the same L1 and L2 results. I am a little surprised that your memory throughput is 22% slower than the UMC tests. I suspect something is still not quite right.
Which motherboard are you using? Do you have a photo of the board? Did you check the part numbers on the individual memory chips on your memory modules to see if they are EDO or FPM? Does the CMOS have a setting for using EDO memory?
Plan your life wisely, you'll be dead before you know it.
Which motherboard are you using? Do you have a photo of the board? Did you check the part numbers on the individual memory chips on your memory modules to see if they are EDO or FPM? Does the CMOS have a setting for using EDO memory?
Its an Acer AP43
Here is a crummy picture: http://postimg.org/image/ckugg9ryh/full/
I will try to take better ones later
The RAM chip part number is MT4C4001JDJ
That appears to be FPM memory, so I would think it is supported.
The board looks nice, but Acer might be dumbing some of the timings down behind the scenes. You could always try using double-banked 256 KB cache instead of single-banked 256 KB cache. While this shouldn't affect the Speedsys scores, it might affect some OEM-specific dumbing down timings - this is a wild shot though.
I sort of recall seeing this board on eBay sometime within the past 5 months. I think it sold for a reasonable amount. If it didn't have an AMI BIOS, I might have been more interested in it. If it had an AWARD BIOS it would be modifiable to take a PS/2 mouse. Did you check to see if there are AWARD BIOSes for this motherboard, or if Acer has an AMI-updated BIOS?
Plan your life wisely, you'll be dead before you know it.
The board looks nice, but Acer might be dumbing some of the timings down behind the scenes. You could always try using double-banked 256 KB cache instead of single-banked 256 KB cache. While this shouldn't affect the Speedsys scores, it might affect some OEM-specific dumbing down timings - this is a wild shot though.
Why deliberately gimp performance?
If that is as fast as it gets, then oh well. Its still a LOT faster than my DX/33
I plan to try 512KB cache
I sort of recall seeing this board on eBay sometime within the past 5 months. I think it sold for a reasonable amount. If it didn't have an AMI BIOS, I might have been more interested in it. If it had an AWARD BIOS it would be modifiable to take a PS/2 mouse. Did you check to see if there are AWARD BIOSes for this motherboard, or if Acer has an AMI-updated BIOS?
Why would an OEM gimp performance? To reduce risk and mitigate potential complications. Here's a excerpt from another post concerning all the complications associated with borderline L2 cache settings on 486s. Zida 4DPS
The majority of motherboards I have come across which have 8 cache DIPs sockets tend to use the double-banked (8 chips) configur […] Show full quote
The majority of motherboards I have come across which have 8 cache DIPs sockets tend to use the double-banked (8 chips) configuration. I have only taken note that when using more than 256 KB cache, it is sometimes a requirement to reduce the L2 cache timings in CMOS. This is especially true when going from 256 KB, double-banked, to 512 KB, single-banked. 1024 KB, double-banked, also seems to prefer slower L2 cache timings. I have not done a comparison of 256 KB double-banked, vs. that of 256 KB single-banked. It could be that need to reduce L2 cache timings are more dependent on the size of your L2 cache instead of single vs. double banked operation. It could also be that single vs. double-banked operation still plays a role in the need to reduce L2 timings but to a significantly lesser extent.
At one point I was working on all this characterisation on several different motherboards and different 486 chipsets. I had several hundred data points on a spreadsheet, but the issues became further complicated as different CPUs, FSB settings, cache amounts, and even the amount of RAM installed all had different requirements for the maximum usable L2/memory CMOS settings. Then I would need to run Memtest and wait hours for a failure. For any given CPU, it was usually a certain Memtest test # which would fail, but for a different CPU, it would be a different test #. It all began taking way too much time.
The main thing I learned from these experiments were:
The more L2 cache (e.g. 1024K vs. 256K), the more system memory (e.g. 128 MB vs. 32 MB), or the faster the FSB (e.g. 40 MHz vs. 33 MHz), the more sensitive the L2 timings will be. The timings in these situations may need to be reduced from the most optimal CMOS settings for a truely stable system.
The faster or more advanced the CPU is per clock, i.e. a Cyrix 5x86-120 vs. an AMD X5-120 or AMD X5-160, the more sensitive the L2 timings will be. The timings in these situations may need to be reduced from the most optimal CMOS settings for a truely stable system. Some systems, for example, may just barely be stable with an X5-160 at the most optimal CMOS settings given your amount of L2 cache and memory, but not with a Cyrix 5x86-120.
Having more memory per stick and using less SIMM slots seems to allow for faster L2 timings.
The most optimal CMOS settings may also be BIOS revision dependent. I have found that using a 4DPS BIOS on a DTK board allowed for using 64 MB SIMMs, while the DTK BIOS did not. Recall from above that using less SIMM slots and denser memory sticks allowed for faster timings.
Single-banked vs. double-banked cache may have an effect on how tight you can set your L2 timings. It may also be cache size-dependent, however the effects of single- vs. double- banked cache have not been studdied w.r.t. a common overall L2 cache size.
Keep in mind that your requirements for a stable system may be less stringent than mine. If you are OK with Windows 98 crashing during installation, or having failed memory on Memtest, then you might be able to get away with tighter CMOS settings.
Plan your life wisely, you'll be dead before you know it.
I think I will just stick with a serial mouse since it has two serial headers.
BTW Just for fun I plugged my serial mouse into my Vista machine to see what would happen and IT WORKED
When I get a chance, I will post all the BIOS options.
The part about stability kind of gave me a headache with all the combinations.
Even if it isn't the fastest board it will still be the fastest 486 I have ever had.
Thanks again
I will see what I can do. Might have to end up loosening the timing with 64/128 RAM and 512 cache
--edit--- 🤣! I just open the USB card I received from ebay and there was two in the package with two different chipsets.
Maybe that will help the chances of one working
I forgot to mention that these cache caveats are mostly an issue when using an FSB at 40 MHz and greater.
Well since it is a 120MHz CPU it needs to run at 40MHz to reach its rated speed.
Not necessarily. My Cyrix 5x86 120 supports a 4x multiplier which suggests that there was at one time a motherboard out there somewhere with a 30mhz bus speed setting, most likely a proprietary design in an OEM system rather than a retail board.
486 machine is coming together
Wish I had shorter IDE/floppy cables.
Major spaghetti. I don't have a proper form factor PSU so i am using a tower style AT supply for now.
I found IE6 to be faster than Opera 8.5x on a 486. I'm not sure why you would have trouble installing Win95. That has always been a breeze for me on a 486. If you thought Win95 was a pain, stay away from Windows NT.
Plan your life wisely, you'll be dead before you know it.
I found IE6 to be faster than Opera 8.5x on a 486. I'm not sure why you would have trouble installing Win95. That has always been a breeze for me on a 486. If you thought Win95 was a pain, stay away from Windows NT.
Right now the biggest reason it is so slow is the 16 MB of RAM. I have 64 MB on the way.
First I tried to install 95 from floppy. After several tries it would always complain about not being able to read the setup disk.
I gave up and installed a CDROM drive (I was going to anyway). Dug out a win 95 disk and it went through the whole install process
just to hang on startup on the next reboot. Trying to start it from a floppy caused a blue screen.
I ended up formatting the CF card and starting over. This time it installed and loaded windows on the next reboot
but then when it was loading drivers on the first run, the cdrom could no longer be found so I ended up copying the files one by one as it asked for them with a floppy.
Once it was done the CDROM worked again but then I had trouble with the network driver installation.
I've got the same motherboard and I'm building a system of it as well. Here comes a warning: do not buy Tseng Labs ET6000. In my case, the card works well in P233MMX, PII-333, PII-450 and shows nothing but garbage when installed into AP43.
There's also an interesting fact: the board bears Acer serial numbers and stuff and bears AOpen logo, yet the AOpen company itself was incorporated only in December 1996, almost two years after the board's release. That's kind of a mystery.
I've got the same motherboard and I'm building a system of it as well. Here comes a warning: do not buy Tseng Labs ET6000. In my case, the card works well in P233MMX, PII-333, PII-450 and shows nothing but garbage when installed into AP43.
I am using an S3 Virge and it is working well. thanks for the info though
There's also an interesting fact: the board bears Acer serial numbers and stuff and bears AOpen logo, yet the AOpen company itself was incorporated only in December 1996, almost two years after the board's release. That's kind of a mystery.
Aopen is (or was) part of Acer
One annoyance if you haven't found it already is there is no output for an HDD light. I am thinking of soldering the HDD light to my CF card adapter to make it work
