nfg.forums

Hello! I have an original X68000 with 1MB RAM, and I am looking to expand to 2MB RAM.  Unfortunately I cannot purchase this board from another user here (https://incognitochip.com/product/memory-expansion-ram-1mb-cz-6be1-module-replica-for-x68000-pc-first-model-original-cz-600ce-b/) as they cannot ship to the US. 

Does anybody have a spare board they would be willing to part with?  I am okay with the original or any of the aftermarket 1MB boards.

The hard drive image includes instructions for a famicom 3d db9 adapter and mentions games need to be patched to use joystick port 2 which I'm sure the HD image has already done.  However, the image included shows a schematic for the built in 6 pin mini din port as well.  Will the patched games still work with 6 pin mini din adapter in addition to joystick port 2?

@rezb1t you're awesome! Thank you again! Looking forward to adding all of these fixes to the image.

Fixed Castles!

Basically, the game tries a DOS malloc call, asking for 8MB of memory. It expects this call to fail and return the amount of memory that can be allocated, which it can then allocate and continue on. As for why the game fails when this call succeeds, I'm not entirely sure. But I'll leave that for another day.

According to this page:

https://gamesx.com/wiki/doku.php?id=x68000:doscall

"If LEN is greater than 0x1000000 it is always an error and it is possible to check the maximum number of bytes that can be reserved."

So I just replaced the constant 0x800000 with 0x1000001 and everything appears to be working.

@rezb1t I tried three levels of Cyber Core, and I didn't encounter any problems, both at 16MHz and at 10MHz, even using different RAM.

What can I say? Congratulations again and thank you!

For those who aren't familiar with Cyber Core, it has 8 levels; during the game, you need to collect power-up orbs of the same color as your spaceship, up to a maximum of three power-ups.

@rezb1t Amazing! Thanks for the quick fix!

I'm sure it's not as popular but Castles has a similar issue where the game will not progress past the intro if you have more than 8mb ram installed. I wonder if it's doing something like that.

I think I fixed the Cyber Core issue, at least the fix worked for a quick test on my system. Attached is another disk image with a patched Y.X, copy over to the Cyber Core folder on the HDD and overwrite the old Y.X.

This one is really weird. There's a PCM address table in the executable that seems to be all correct, but it gets overwritten at runtime by.. something(haven't figured out what yet) and the invalid value 0x00808080 ends up in the table. Later on this value gets used as a source address to copy memory to the PCM hardware via DMA. This happens no matter how much RAM you have... but if you have more than 8MB, the DMA ends up reading uninitialized data which comes out as harsh and unpleasant audio. If you have 8MB or less RAM, I think it just reads all 0s which is completely silent.

Anyway this behavior is completely broken and I did try to figure out a more proper fix, but ended up just going with a quick hack that falls back to a known good entry in the table if the address is equal to or larger than 0x800000. This seems to work, but I don't have enough familiarity with this game to know for sure that I didn't break anything.

Testing would be appreciated, let me know if you find any issues.

EDIT: Tested over a couple of levels and everything seems to be in order!

@rezb1t Congratulations, it really works well at 16MHz (it will be a bit fast) and 10MHz.

It would be nice if something could be done for Cyber Core; on the hardware side I have done many tests with different RAM models and addresses, but the audio glitches remain if you have more than 8MB of RAM.

Unfortunately, as you will know, if the RAM is reduced to less than 10MB, Valis II will no longer work in 2HDboot mode.

Nice! That'll work. Yeah the 4K CE should work perfectly. The FM Towns and X68000 shouldn't require any of the pro specific features.

Quote from: rezb1t on November 13, 2025, 05:59:34 AMThat cable from RetroTink won't work for this. See the following disclaimer:

"The cable does not have a sync combiner - a valid composite sync signal must be present on HD15 Pin 13"

A sync combiner is necessary for the X68000 to convert to SCART. incrediblehark linked the same adapter I use for this purpose, but I was unable to get the X68000 working with the RetroTink 5x at all.

If you want to scale the X68000 I recommend either the OSSC Pro, or the RetroTink 4K CE/Pro (either works).

I personally use a RT4K Pro.

I was going to try making this adapter which I think is a sync combiner.  https://www.cathoderayblog.com/converting-rgbhv-to-rgbs-for-the-gbs-control/ and place it before the retrotink vga to scart cable.  I understand the retrotink 5x needs RGBs.  I was just saying the cable will solve the TTL 5v voltage input that I believe the adapter may not and bring it down to safe levels.

Would the less expensive retorink 4k ce work for my needs regarding the Sharp X68000 and FM Towns PCs?  I already have a full Retrotink 4k but hate disconnecting stuff to use it.  Worst case I rather not have to buy another $700 device.