About the first isa slot, that does not worry me much, i could simply not use it, anyway the parallel port controller has a daughter card the would fit nicely there 😀

But the pins are rather easily repairable. I fixed nes consoles connectors in worse shape. The trick is to use a small paper trombone, straighten it, heat one end till red hot, then smash it with a hammer to flatten it. You end up with something like a mini metal paddle. Great tool to straighten connector pins 😁 Then insert fine grit sand paper in the slot to clean off.

Ok, i took a brake from that rusty board and decided to start building back a machine with motherboard#2 and all the parts.
After taking the last couple cards off board 2 and removing it from the case i was shocked to notice the battery, that bitch, had leaked on this board too 😳

Those damned SMD batteries were really a crap idea werent they?

I immediately unsoldered that battery and washed the area. "Fortunately" its not really near as bad as the other board. Damage was mostly concentrated on one trace, and some discoloration on another one. The damaged trace was holding by a hair though so i bridged it with solder. This board is not equipped with a battery header like the other one so i connected two wires to the board. I will install a 3.6v NIcD 3xpack at the other end , FAR AWAY from the board. At this point im pretty confident this board is good to go 😀

I also installed that Evergreen upgrade on board 2, that went very well. Heres a better picture of that thing, once installed.

I have a new question for you guys. This one is about Cache!
Back when i first tested board 2, i remember seeing 64kb cache on the bootscreen. Both boards have exactly the same cache chips, 8 kb each it would seem. 8 chips for 64kb. Board 1 has 8 chips, But board#2 as 9! See pictures :


So why does the above board#2 has 9 cache chips? Backup chip?

While we are talking cache, I know the boards can support up to 256kb, is there any real-life benefit to upgrading this?

Tomorrow’s goal is to assemble that machine, power it up and see how it fares.
Thanks for help so far all of you, I hope you enjoy reading my posts, im having a blast of fun with this project!

the thing with cache is that there is a 2nd set of memory called the TAG ram. This ram told the cpu what data was in the cache without acutally looking at the cache. This chip needs to be upgraded with the rest of the cache. a more detailed explanation can be found here: http://www.pcguide.com/ref/mbsys/cache/charCa … eability-c.html

That being said, on the green board, the 2 chips to the left are your tag ram. where the 9th chip on the other board is your tag ram. 9 chips is VERY common as manufacturers could use the same chip for the cache as the tag ram, cutting costs and making upgrades easier. All the more reason to use board #2! As for your next question about the quantity of cache, the simple answer is, more is better, and there is no such thing as too much. Just like regular ram. The early 486's had 64kb. most boards stopped at 256k as this was plenty for 99% of people, but the later and more advanced boards can have up to 1mb.

Do you have another 486 machine with 256kb of cache to salvage? upgrading to 256kb will help performance and because of how often 256kb came standard, its relatively cheap. I have about 3 SETS of cache chips i've salvaged and wouldn't mind selling you one.

while on the subject of cache, the jumpers on your cpu upgrade, several of them change how the system uses cache, and if i'm not mistaken, it looks like it is set for write-through. more information on what the means is here: http://www.pcguide.com/ref/mbsys/cache/func.htm but you might want to consider setting that to write-back for maximum performance. that said, some boards wont do write back cache, and if yours doesnt, just turn it back and go on with life.

on a side note, look at connector J11 on board #2. its right next to the bios. $5 says that's a external battery connection.

Right you are! I missed that one 🤣 There is a battery header.

You sir know a great deal about those computers, that read on the tag cache was very enlightening. Did not fully grasp some aspects of it yet, such as relation between Tag cache size and bit width. But im getting tired, will sleep on it. This is an aspect of computing architecture i was totally unaware of. Even tough ive been messing with computers for almost 20years.

About that cache upgrade, i dont have a 486 with 256kb around. The possibility to upgrade could interest me, but first ill get that system up and running. I also have a P90 hanging around, have not played with it much. Ill check it out soon, make sure the battery is not leaking all over, and check the cache too!

Now who said that resurrecting old computers was useless? you learn stuff!

The thing is, with the Pentium pro and processors after it, the l2 cache was on the cpu die. so they put the proper size tag ram on there and the whole issue became moot. Computers are SO easy to "build" today, just about any swinging dick can get one together and have it work. makes me sad sometimes, but when i was in school i was the ONLY kid in class with a computer. I was also the first one on the internet and I lived in a GOOD neighborhood. I was nearly expelled from school 3 years in a row for messing with the schools network. I could go into the story in more detail if you want but lets just say I had an addiction to the original starcraft, and I would play it on the school computers. only to have the tech people delete it, so I started hiding copies of the software on the school servers...

🤣, talking of school+computer issue, i got banned of the computer laboratory in my high school.

I had made a Qbasic program that would generate a random high pitched sound between 16k and 20k hertz. In the free hours, i copied that program on 30 computers then with 5 buddies we ran the program on all computers at the same time. That made a high pitched symphony that sent kids crying in all direction, the director could hear the sound from his office two stairs below, he furiously roamed the school searching for the source of offending sound. It took him a while to trace it. There was at least 20 min of ultrasound goodness before my mischief was eventually found and stopped. Apparently this could be heard throughout the school. Ive heard people talking about it for 2 days. But i was forever banned of the laboratory, i still think it was worth it 🤣.

I wouldn't worry too much about getting extra cache. In my testing I found that less, faster cache is better than more, slower cache.
Those chips you've got appear to be 15ns which are pretty decent as far as SRAM chips go for 486 systems.
Try to set the lowest cache wait states/latency that your motherboard will allow.
If you do decide to upgrade to 128KB or 256KB at least make sure that its 15ns and no higher. If you have to increase the wait states/latency you may actually find a slight reduction in performance even with the bigger cache.

Best way is probably just try to salvage another motherboard that you can steal the cache from.

In my '386DX40 Build' topic in the System Specs forum there was a fairly long discussion about upgrading cache on our motherboards including the TAG RAM. It was for a 386 but the same basic principles apply.

luckybob wrote:

imho that evergreen upgrade is worth more than anything else in that case. If it still works, post the autoexec.bat and config. […]
Show full quote

imho that evergreen upgrade is worth more than anything else in that case. If it still works, post the autoexec.bat and config.sys files from the root of the hard drive. If there are any special utilities, that will tell us where/what they are.

as for the corrosion, I'd personally take the board under some water and wash it with soap and water. use and old toothbrush to try to remove all the crud you could. and let it dry before turning it back on!

What does the other board look like?

edit: if you have 32mb of ram in this 486, then all 8 sticks are 4mb sticks. which is the max for 30 pin simms.

If the topic starter has good solder skills i recommend to desolder that 8-bit slot and solder a new one in from an dead motherboard. Because that green corrosion you never get rid of on those contact points..

And having an question.. Whats the use of those 32-bits local bus slots?

My soldering skills are descent. Thing is that i dont have a scrap board with an isa slot atm. Do you say that because you think corrosion could still spread? Because otherwise as i said earlier, i have a daughterboard that eats up a card space without using the connector.

Robin4 wrote:

And having an question.. Whats the use of those 32-bits local bus slots?

I also wonder about those, never seen a card using that, maybe for industrial custom projects?

I couldn't find the exact datasheet for your cache rams, but I am strongly under the impression that they are more than likely 25ns, not 15ns. This would also be consistent with the age of the board (a fairly early one, note the lack of vlb).

Whether or not upgrading to something faster would increase performance after memory settings are adjusted is speculation, but seeing as how 15ns 256kbit chips are easy to come by, you don't have much to lose by trying.

MaxWar wrote:

My soldering skills are descent. Thing is that i dont have a scrap board with an isa slot atm. Do you say that because you think corrosion could still spread? Because otherwise as i said earlier, i have a daughterboard that eats up a card space without using the connector.

No the corrosion will not spread further, but you never get it good clean.. And the contacts arent also in a good shape.. So its maybe an better idea of desolder that one and replace with a good one.. and you will be able to use it again.

Anonymous Coward wrote:

I couldn't find the exact datasheet for your cache rams, but I am strongly under the impression that they are more than likely 25ns, not 15ns. This would also be consistent with the age of the board (a fairly early one, note the lack of vlb).

Whether or not upgrading to something faster would increase performance after memory settings are adjusted is speculation, but seeing as how 15ns 256kbit chips are easy to come by, you don't have much to lose by trying.

I will run my machine as is for now, but i take good note if i decide to pimp it up in the future, any recommendation as to a good source for those chips?

I checked digikey and ebay but did not find anything.

Otherwise, i have a noob question about ram arrangement on the 486 boards. Supposing you have 2 brands of ram sticks, or more. Is there any advantage to have the ram arranged in a particular way? Like all same brands in same bank? or both banks symmetrical?
Both my boards have 2 different brands (2 x 4 sticks) and they are currently set as each brand has its own bank. I plan to scavenge some for sound cards then replace them with spare ones of lower size.

You probably should keep each brand in it's own bank, they may work if the different brands are the same size but there's no reason to mix them up.

As for cache chips I just went off this
http://www.digchip.com/datasheets/parts/datas … M3-65764H-5.php

Which says 'as fast as 15ns are available' but that might be talking about available models not these specific chips.

30 pin simms MUST be installed in IDENTICAL sets of 4. brand doesnt matter as long as they are physically the same. 72 pin sims usually must be installed in pairs. Basically, if you look at the board, if it has 2 slots designates as bank 0, the both slots MUST be filled.

personally i'd wat and scavenge chips off another board before I bought one off ebay. just keep your eyes open at thrift stores. I usually pick up a computer from a thrift store about twice a month. ( retro one anyway)

Ok, heres an update.Computer is in good part assembled and functional. Ill not be messing around with ram yet.

-New remote NiCd battery soldered in
-Switch and LED headers, turbo etc is connected and work fine.
-All basic control boards installed
-VGA Wonder XL card installed
-Powers up fine, PSU clean and quiet.
-Left to charge battery for a while.
-Go to bios, seems to remember settings now.
-Installed 3.5 floppy + 1.6gb hdd.

Heres what it looks like atm:

Everything works great, but as expected, HD is only recognized as 500ish MB instead of 1.6gb...

I have another HDD but its 150mb, a bit on the thin side for my needs. What do you guys thinks about drive overlay software?
Good or not good? How does it install and at the same time lets you format the whole drive? Do you format With the overlay using a special boot floppy? (would make sense ) Does it eats up conventionnal memory ? Never used those, so its all new, or maybe i should say old 😜
Other options would be from what i understand, bios upgrade or upgrading controller card? Or then simply leave it at 504mb...

Btw, i also got one of those IDE-CF card adapter, i do not have a CF card atm though, how can you make those work with a 486?
That would be an intersting option!

I've used Maxblast to setup a Dynamic Drive Overlay before and I don't really have issues with it. Works pretty well. Takes up a couple of KB in memory but nothing you'll really notice. You boot off the floppy, and run the install. It does reformat the drive as part of the install though.

You can get it here: http://members.shaw.ca/rinocanada/hdutils.htm
It works on CF cards as well.

Thanks for that link, in the meantime i also downloaded ontrack disk manager 10.
Ill try both and try to learn about them. Im not lacking in floppies, bought two boxes of 50 brand new sealed memorex floppies for 1$ each at a liquidation market. Yes, 2$ for 100 floppies! 2 weeks before i purchased 20 new TDK for 15$ shipped. I could have had 750 floppies for that sum 😳

Im spoiled now...

Edit : I used maxblast to format my drive then installed dos 6.22, no problem so far full disk is recognized. But when i rebooted after the install, upon loading HIMEM i got the PARITY ERROR SYSTEM HALTED BOLD CAPITAL CHARACTERS LARGE GRAIN RESOLUTION MESSAGE OF DEATH.

...

Ram issue ? I went to bios and enabled full ram count + parity check. Did not give me any errors.

Im done for today, but i guess ill have to do some ram swapping next 🤣. Or is there a very specialized app that could help me diagnostic this ram to a precision level where it tells me which stick is bad ? If that is actually the real cause of this error of course.
I was also wondering if i could just put two large EDO ram sticks and remove all the 30 pin. That would be practical. Ill have to try it out. I have 32mb EDO sticks doing nothing. I dont give a damn if it only reads it at 32mb total.

Norton Utilities for DOS has a memory test if memory serves; there's also memtest86 which is a free download.
I don't know of anything that will tell you exactly which module is faulty though, it will probably just give you an address in hex which you can use to work it out. (I had this problem with my 286 and I had 36 memory chips on the motherboard to pick from 🙁 Luckily I managed to narrow it down to one bank and found the faulty one pretty quickly).

The 72 pin SIMMs are worth a try. You only need one 72pin SIMM in a 486 to make up a bank as it only has a 32 bit external bus; with Pentium or newer you needed 2 because it had a 64 bit external bus.
I doubt that it would require EDO due to the age of the board, although I could be wrong. It most likely just requires Fast Page memory, and it may or may not work with EDO modules. There's no easy way that I know of to tell FPM and EDO modules apart.
Just try it and see 😀