I upgraded a RAM expansion board. 4MB board to 8MB. No issues now.

[cr4zymanz0r]

So, originally I was hoping to just post my success and a how-to guide. Since it was just a partial success I'll divide this between a how-to and why it's not utilizing the RAM.

About and how-to:
I have a BasicHouse KGB-PRK II ram expansion board. Here are some pics of it before I upgraded the RAM http://imgur.com/a/mfjQG.
What little bit I can find on it online seems to suggest that people think it's a 2MB expansion board. That's what I assumed too and was running it that way. However, I tried out memtest68k and it was reporting 6MB RAM (2MB built-in RAM + 4MB expansion). Now, as you can see in the pics there are some unpopulated sockets next to the existing RAM chips. From what I could tell it was just missing the RAM chips and some ceramic capacitors.

I had the simple idea of finding more of the RAM chips (TC514400AZ-80, found them on ebay), the capacitors, then soldering it all in. The capacitors currently on the RAM board were marked "104" which is some sort or product code that basically means they're 0.1 uF capacitance. I'm not sure of the voltage. It looked like my main choices were 50V and 100V. I ended up getting 50V off of digikey. While they are physically a little smaller than the existing 104's on the board, I don't think the difference between 50V or 100V on those ceramic capacitors should make a difference (correct me if I'm wrong).

I got the last of the parts in earlier this week and got them soldered in tonight. Here's some pics of took afterwards http://imgur.com/a/8viRI. Before there were 8 of the TC514400AZ-80 ram chips on the board (each chip is 512KByte RAM each) which is 4MB, then adding 8 more should bring it up to 8MB. However, I can only get i to recognize 6MB.
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Issue and troubleshooting:
I can't find any documentation on this RAM board, so I've just had to make educated guesses based on documentation from other boards and pictures I've seen. If you look at one of the pictures that's zoomed in on the jumpers you can set there's 2 sets: J1 and JP3. I'm highly under the assumption the J1 jumper relates to which expansion bay the board is when using a FPU co-processor (which I'm not using), so I believe we can disregard that jumper.

The JP3 jumper is where the RAM action is at. I'll refer to the sets of 2 pins as jumper 1, 2, 3, 4, and 5 going from left to right. Originally the board just had jumpers 1 and 2 active to have the 4MB on the board used. After soldering in the missing capacitors and additional RAM chips, it still only reported 4MB with only jumpers 1 and 2 active. With 1, 2, and 3 active It would now report 6MB RAM. Now before I get to the next part I'll state that I use memtest68k to detect the RAM initially. I like it because it it detects the max amount of RAM present regardless of the switch.x settings stored in sram. Anyway, usually memtest68k detects the system ram amount very quickly. However, when jumpers 1, 2, 3, AND 4 were active it took memtest68k a couple of additional seconds of sitting there to detect the RAM amount, but then still only detects 8MB (2MB from the X68000 itself, and 6MB from the RAM expansion board). I also tried making 1, 2, 3, 4, and 5 all active at the same time but then only saw the original 2MB system RAM. I also tried 1, 2, and 4 but then it only detected 6MB (2MB system + 4MB expansion).

I've occasionally found other pictures of the board that already has all of the ram sockets populated and they always have jumpers 1, 2, 3, and 4 being the only active ones. The fact that memtest68k hangs/thinks for a couple of extra seconds when I set the jumpers to (what is apparently) 8MB makes me think it starts to see that portion of the RAM, but then something makes it stop. I also tried going into switch.x and setting the RAM to 9MB and 10MB in the hopes that maybe memtest68 just wasn't detecting it right. I had the same results though. LHES (or whatever that menu is on the HDD image) wouldn't detect above 8MB total RAM either. Also note that I tested this on an Expert and a XVI with the same results. I also tried both expansion bays.

It's probably a long shot, but does anybody else here know a lot about the BasicHouse RAM board? My soldering quality was consistent across all the RAM chips and capacitors so I really don't think the issue is a bad connection from soldering. I could theorize that maybe 1 to 4 of the 8 RAM chips I received are bad, but I don't know what 'normal' behavior would be for a bad ram chip on an expansion board. I'm also unaware of a way to test to see what specific RAM chip it starts to fail at (if that is the issue). I feel pretty noobish compared to a lot of the other frequent posters here, so I'd appreciate any help or insight that I can get.

[SuperDeadite]

RAM boards always have dipswitches or jumpers as RAM boards have to be assigned a specific order since they function as one continous block.  Let's say you have 2mb internal, in that case you would want the dips/jumps set to 2MB of RAM, telling the system to use the board after the first 2mb of the system is full.

For example I have an XVI with an XSIMVI and a 4mb I/O board.  The computer has 8mb on the mobo, so I set my I/O board to 8mbs, allowing me to use the full 12mbs.

If you had say a Super with 2 4mb I/O boards, board one should be set to 2mbs, while board 2 should be set to 6mbs.

Get it?

[cr4zymanz0r]

Yes, I understand the concept from what I read about the other RAM boards on the wiki. I'm not entirely sure if this BasicHouse board's jumpers behave the same way though. I'll give more detail and see what you think.

This is the only RAM board I have and without it installed both my Expert and my XVI only have 2MB RAM internally. Now before I soldered more RAM into the RAM board it was a 4MB board, jumpers 1 and 2 were set, and all 4MB from the board was detected (making a total of 6MB RAM for the system). Now after soldering in the additional 4MB RAM into the RAM board, if the jumper settings were just like the other RAM boards to set RAM as one continuous block then I would think I wouldn't have to change them for all 8MB on the RAM board (10MB system total) to be recognized. However it still only detected the original 4MB on the RAM board. When also activating jumper 3 along with 1 and 2 it detected 6MB on the RAM board, then when 1, 2, 3, and 4 are activated it hangs for a few seconds in memtest68k as if it's trying to see the last of the RAM, but still only sees 6MB from the RAM board.

This makes me assume the jumper settings on this RAM board are used to tell it how much RAM is present on the board with in chunks of 2MB per jumper. Now I freely admit I could be wrong and don't know if that approach is or isn't possible. Maybe the X68000 works in such a way that _ANY_ RAM board would require jumper settings for determining how to set RAM as one continuous block or maybe the RAM board could automate that? If the jumpers on this RAM board do work like the ones on other RAM boards, then I don't understand how it was detecting all of the original 4MB on the board before I added more, but not after I added more until I changed jumper settings. Is it possible to have what appears to be success or partial success with the wrong jumper settings?

If you still think/know the jumpers are for setting RAM as one continuous block, (due to lack of documentation on this RAM board) do you suggest I just try every combination of jumper settings in an attempt to find the correct one?

[Fix_Metal]

IMO, since you have just modded a basic (working) board, you should had took a look at which lines are getting where.
I mean, the board is clearly been made for having more than the memory it had, but that's just a bunch of holes.
If memories can't be seen, than most likely control signals are not routed/handled correctly.
You should really check the datasheet and check if control lines are routed. Then look where they end up, since there's so much 74xxx logic stuff there.
The ceramics are fine, obviously. As these work over the CPU, most likely they run @ 5V, and those 100nF are up to attenuate high frequencies ripples.
Here's the datasheet.
You should moreover investigate about the purpose of those jumpers, anyway.

[cr4zymanz0r]

SUCCESS!!!

I got out my multimeter to start trying to figure out where all the RAM chips were connected. I assumed that each corresponding pin of each RAM chip was connected (such as as pin 1 on every RAM chip are connected to each other). This assumption proved correct so I started making sure all of the pins of the new RAM chips I soldered in had a proper connection.
Out of the 160 RAM pins I soldered, ONE was apparently a cold solder joint. It looked ok physically, but it was getting a ton of resistance on my multimeter. I resoldered that one pin and now the RAM board is a 8MB RAM board, so 10MB total system RAM 

I sure feel like a doofus for that being the problem, but I'm happy it's fully working now. Maybe this will help someone with upgrading their own RAM boards that have additional empty solder points for more RAM chips.

[neko68k]

you should write a page on the wiki

[BlueBMW]

I sure feel like a doofus for that being the problem, but I'm happy it's fully working now. Maybe this will help someone with upgrading their own RAM boards that have additional empty solder points for more RAM chips.

Nah, the doofus is the person who assumes that their solder work cant possibly be flawed and doesnt bother to check it!  Congrats on figuring it out.

I'd be curious to find out who else has one of these Basic House boards and can check what ram chips are installed in them.  I've always heard they were 2mb boards or 4mb boards when fully populated.  This information might be in error.

[Fix_Metal]

Simpler than I thought.
Congrats 

[cr4zymanz0r]

you should write a page on the wiki

If I knew how to go about that or who to submit it to I might could do that.

I'd be curious to find out who else has one of these Basic House boards and can check what ram chips are installed in them.  I've always heard they were 2mb boards or 4mb boards when fully populated.  This information might be in error.

If it helps you any, I did check out the original set of RAM chips on the board. They appear to be the ones that were installed by default. The soldering on them is way too clean and consistent to have been done by hand.

[Fix_Metal]

you should write a page on the wiki

Some time ago Lawrence wrote that the wiki is locked because the upgrade didn't go well, so I don't think that'd be possible.
Possibly, migrating all the articles to a different (better) wiki would be the best solution, imo.

[msxtrd]

I'd be curious to find out who else has one of these Basic House boards and can check what ram chips are installed in them.  I've always heard they were 2mb boards or 4mb boards when fully populated.  This information might be in error.

It seems that there must be two versions of these boards. Some populated with 512k and some with 256k RAM. The one I have here is half way populated with HM514260AZ8 RAM (256k) that totals 2MB.

I'm wondering what will happen if I solder in 8x512k RAM chips, if it turns to a 6MB board?

cr4zymanz0r,  could you take some high res photos of the ICs on the board and upload to imgur? I could compare if they are the same on both boards. And what are the values written on the capacitors?

[cr4zymanz0r]

I'd be curious to find out who else has one of these Basic House boards and can check what ram chips are installed in them.  I've always heard they were 2mb boards or 4mb boards when fully populated.  This information might be in error.

It seems that there must be two versions of these boards. Some populated with 512k and some with 256k RAM. The one I have here is half way populated with HM514260AZ8 RAM (256k) that totals 2MB.

I'm wondering what will happen if I solder in 8x512k RAM chips, if it turns to a 6MB board?

cr4zymanz0r,  could you take some high res photos of the ICs on the board and upload to imgur? I could compare if they are the same on both boards. And what are the values written on the capacitors?

The pictures linked in my opening post are high res. You just have to click on each pic to make it bigger, or download them for the full size. Pretty much every IC model is visible in the pics.

[msxtrd]

Ok, I checked the parts and they seem to be the same all over the board, except ram chips. Both oscillators are 16MHz (the one here has part nr. TCO-707F - this should make no difference?).

It would be nice to get hold of the manual for dip switches, because I can see that memtest68k does run full test of this board without problems and reports correct total amount of RAM, but there is a conflict with my other expansion card, which is installed internally in Compact XVI (in the custom internal ram/fpu slot). If those two boards are plugged at the same time,  4MB games will have corrupted graphics or throw somekind of bus error. Maybe this could be fixed with correct jumper settings, as it seems that games do not see the RAM in the correct way, and something goes wrong.

[cr4zymanz0r]

I'm pretty sure I understand the jumper switches that correspond to the RAM when used as a single RAM expansion. However, I'm not really familiar with the Compact's internal slot or how things have to be set up when using 2 RAM expansions. Maybe someone here with more knowledge can shed some light.

[eidis]

Hi Cr4zymanz0r !

It is just like SuperDeadite explained, the RAM has to be configured as one continuous block. Internal RAM expansion has higher priority than the I/O slot expansion RAM and should be configured to address right after the built in RAM. Here is an example. Let's suppose that it is an ACE HD

000000 - 100000    = Built in RAM (1MB)
100000 - 200000    = Internal 1MB RAM expansion
200000 - 400000    = Additional I/O slot 2MB RAM board #1 (Jumpers must be set to 2MB)
400000 - 600000    = Additional I/O slot 2MB RAM board #2 (Jumpers must be set to 4MB)

Total: 6Mb

Keep the scene alive !
Eidis

[98pacecar]

Just finished doing this upgrade for myself. Took a 2mb board to the full 8mb. So far, no problems, but it's still early in running memtest. I did go with sockets for the chips I added, just in case anything goes wrong. The board will just *barely* fit in slot 1 but looks like it should have more than enough room for a second card if it's in slot 2.

Just for future reference, the capacitors to be added are 100v.

[msxtrd]

I must revise some of the conclusions I did post previously. Today I did solder 8 RAM chips onto my half populated KGB-PRK-II ram expansion. After plugging it into the computer (XVI Compact), and running Memtest68k it did report 10MB of total RAM!? Woot? Previously I thought that HM514260AZ8 RAM chips were 256K as they are sold on ebay as 256K??? But on this memory expansion board they are actually 512K.
My mistake came out of that I did plug in internal expansion of 2MB (into internal proprietary socket) and the half populated KGB-PRK II board into an I/O slot, that would total 2MB system+ 2MB internal + 2MB I/O = should be 6MB total. Memtest68k did report 6MB ,but it did actually only count system memory + 4MB on KGB-PRK II. Internal 2MB expansion was completely undetected in this case.
If I unplug now KGB-PRK II, Memtest68K will detect the internal 2MB expansion and report correctly 4096KB of total ram. When KGB-PRK II is plugged in the internal 2MB is ignored, and totals to 10MB (2 MB system + 8 MB KGB-PRK II).

Anway, great to have 10MB now

If someone finds a manual for jumpers of KGB-PRK II it could be that it can be configured so the internal expansion could be detected correctly, but I'm probably dreaming . I'm not even sure if it is possible...

Some pictures: http://imgur.com/a/8s8F1

[98pacecar]

Out of curiosity, are you running this in 16mhz mode? Your speed of the 10mb is close to twice what I'm seeing in my super, so I assume that's the difference.

[msxtrd]

Yes, at 10 MHz it is 4256KB/s

[98pacecar]

I don't remember exactly, but that is very close to what I am seeing at 10mhz as well. Thanks for checking on that for me!