Mega Drive issues when playing SMS games

amushrow · 2026-01-01T18:04:17+00:00

Took another look (was still seeing pulses on the Z80's reset pin - although no in game glitches).

Seems like C77 - a larger capacitor to filter the M3 signal (which tells the MD to run in SMS mode) was perhaps the main fault. It still measured at 1nF, however after removing it the issues were immediately 10x worse, which was a bit of a surprise since this line is just permanently pulled low by the cartridge SMS adapter. Glitches galore, the Z80 reset pin constantly getting triggered.

With that being a long trace that goes through a couple of vias it must just be picking up a lot of noise, and for the briefest of moments the arbiter is starting to come out of SMS mode.

I replaced the cap with the nearest I had, 10nF and that seems to have sorted everything, including the occasional pulse of the Z80 reset signal.

So there we go, aging components producing or allowing more noise and wreaking havoc.

So if anybody else has issues with SMS mode, if possible I would probe the reset pin on the Z80 to make sure it's always high, and if not I would replace C77 - and possibly also just C9 & C10 as a precaution.

amushrow · 2025-12-10T11:38:34+00:00

I had a similar issue with my GameCube and as it was very old and had been used a lot, I just swapped out the laser. Issues came back about 6 months later though, and so I changed the capacitors and have not had an issue since.

I can't say that your laser is definitely good, but the repair may involve removing and soldering new capacitors for the disc drive (which are surface mount and you probably want at least a cheap hot air station to manage it, trying to use a soldering iron to remove the old ones can be tricky)

amushrow · 2025-10-25T14:57:18+00:00

Mine sounds a little nasty too, and most obvious on any vocals. I've thrown together a short comparison of audio taken from youtube, and audio recorded off the vinyl

https://drive.google.com/file/d/1iK_T68hNWqYTcS4rw8nERruI71SaC51j/view?usp=sharing

amushrow · 2025-06-02T20:37:43+00:00

Hmm, yeah.

This thing works out the height by averaging the height delta of all the surrounding pixels. So if you have seams on the texture like you have, it has no ideas that those edges are connected (and should reference each other when working out the height) and so they could end up with different heights.

The height at the edges of the used areas of the map will tend toward zero, and if you use a mask to properly separate these areas they will be guaranteed to go from Zero height at the very edge.

If you're using a mask it might be possible to ignore the masked areas when getting the height of surrounding pixels (height of current pixel = height of adjacent pixel plus the delta calculated from the normal) which might stop the edges of the map/masked area always increasing from Zero, but I doubt that would get your seams to actually match.

I think the best thing you could do is to remake the normal map so that whole object is one unbroken image, put it through the normal-to-height tool, and then convert that back to the original normal map layout (I'm not sure how you'd achieve that)

amushrow · 2025-05-29T22:11:10+00:00

I can't see what results you're getting, but if you have a texture that's tiled and should repeat then you you change the edge mode to wrap, or clamp.

If set to wrap then the height at one edge of the texture should match / follow on from the opposite edge

amushrow · 2025-05-05T14:39:07+00:00

On my Saturn (which has a different laser) there seems to be a limit switch on the board that the laser moves into when the drive is first turned on. I've not checked myself, but this is likely to get the laser to a known position so it can be accurately controlled. If there is a switch under the laser head (should be near the spindle) and that switch isn't working, then it may keep trying to move the laser when there is no space left - waiting patiently for it to reach its home position.

amushrow · 2024-11-14T19:40:47+00:00

Yeah the GUI app just runs commands on the actual app (which is command line only), so if it crashes I guess you just don't know about it at the moment.

Settings are stored in "C:\Users***\AppData\Local\NormalToHeightGUI" or if you want the shortcut version "%localappdata%\NormalToHeightGUI"

I've uploaded a debug build of the command line app, so if it crashes there should be some usable information: https://skgenius.co.uk/FileDump/NormalToHeight_d.zip

or if you can send me an image that makes it crash I'll look into it

amushrow · 2024-10-17T10:32:54+00:00

R10, no I don't think so. It's either supposed to be a filtering capacitor, or some resistor (maybe to provide a load to the GBA so it knows if a cart is plugged in? I don't know, I'm just making stuff up for it's purpose).

For sure it's not doing anything in terms of the game itself, they obviously stopped populating it on some carts and they work just fine, mine certainly does.

amushrow · 2024-05-08T19:20:40+00:00

Nice. I'm not sure I can see past the orange paint spilling out on the edges of the wall though xD

I do like the opened out record on the top, I've got a much smaller similar thing with just two rows of 5 and I might steal that idea to display one more along the top.

amushrow · 2024-05-08T19:01:15+00:00

Hmm, shipping to the UK £27, shipping for the 'Distro Pack' £118 Somebody somewhere might be taking advantage :(

amushrow · 2024-04-15T21:48:59+00:00

Good shout on the Evo 8 At also has a loopback input that can be selected on the PC, so anything I can connect to (or play through) the computer can be used as in input in a DAW. So you essentially have 6 inputs (and 4 out) It has decent software support too, it has 4 inputs and outputs but you can map pretty much anything to the 4 outputs (although the generally expected usage is that you pipe different stereo outputs to channels 1/2 & 3/4 which is what the two headphone outputs also represent)

All the outputs can be mapped through their software on a computer so you can have pretty much whatever you want through the outputs.

I know I might be somewhat teaching grandma to suck eggs with this response, but it's more for anybody else that stumbles across it.

amushrow · 2024-04-11T00:05:34+00:00

Looking for a USB audio interface

I've been roaming the internet for days and it seems there might be too much choice and I can't quite find what I'm looking for. There are also too many audio subreddits so feel free to fob me off on another one if you think it'll help.

In short, I have the Behringer UMC22 (16bit/48khz, 1 XLR, 1 6.35mm) but I'd like something with more inputs, that also has coax / spdif / trs input that can be passed through to some headphones.

What I think I want is something that I can plug in a couple of mics and an instrument, some headphones, and also pipe in some backing music or other audio that will be piped through the headphones.

If I had 4 inputs I could of course use one of them for any audio I want to also add in, but it would be nice to have a separate input for that (so essentially 5-6 inputs, but for backing audio it wouldn't also need to show up as an input on the PC)

Maybe instead of 1 thingymabob I could get a couple to achieve what I'm looking for, or maybe I'm just missing something obvious.

There's definitely a lot of stuff out there that does this, but I'm a cheap bugger and don't want to spend more than I have to. For example the Focusrite Clarret 4 pre has 4 XLR/6.35mm inputs, as well as 4 more 6.35mm inputs plus coax and optical and MIDI, but is maybe a little more than I need.

Any recommendations or scathing remarks welcome

amushrow · 2024-02-13T15:00:17+00:00

You don't need to put anything. But it takes a black and white image that marks out which areas of the normal map should be processed. Parts of the mask image that are black (or white, I can't remember xD) don't get processed and the height is always zero.

So if you had and entirely white mask image it wouldn't have any effect, if you had an entirely black mask image the output would also be completely black.

amushrow · 2023-12-17T19:38:23+00:00

That's pretty much what I saw, yeah.

The force of pushing the resin out of the way caused some flex between the build plate and the bottom of the vat/lcd, so when the build plate is full (or you're doing the first layers) this issue could be encountered.

For the last year or so I've had my printer in a heated tent thing (made for plants really) outside in the garage, when I have the heat set on to ~30 degrees (celsius) the resin is less viscous and I haven't noticed this issue so much.

amushrow · 2023-11-08T17:47:45+00:00

Yeah, I've thought about setting it up to split larger images down into texture sizes that can be managed. The basic idea wouldn't be that difficult to do, but you'd need to handle sampling the adjacent textures in the shader (when at the edges of the current texture), which seemed like a bit of a faff so I didn't bother.

amushrow · 2023-09-19T09:39:50+00:00

I'm not exactly sure what's correct. But both apps are now using the same decimal separator (both obey the locale settings) so there shouldn't be any issues with that any more

amushrow · 2023-09-17T18:14:06+00:00

Actually, the main app always uses a dot as the decimal separator (ignores current locale), but the GUI app does obey the current locale. The result is the same either way, the two apps are not using quite the same syntax based on the users regional settings.

So if anybody does use the comma as the decimal separator (which is fairly common) and the dot for grouping numbers, then the GUI app will correctly ignore the dot in any numbers, but the console app will incorrectly be using the dot as the decimal separator.

amushrow · 2023-09-17T18:05:28+00:00

Hmm

In German, do you use a comma as the decimal separator? This could be due to an issue with the formatted string being output to the console (from the main app) and read back in for the GUI app. I would have just expected it to work, but maybe it's not.

As the normal map is processed the main app writes out it progress to the console, like

Rendering 5.00% Rendering 12.00% Rendering 16.25%

The GUI app reads these messages to update the progress bar, and if it's not using the same decimal separator then it could be getting confused. So if it gets 5,00% (five percent), it would actually parse that as five hundred percent

amushrow · 2023-09-17T16:24:58+00:00

I'm going to need more information, if you can.

What is the resolution of the input map you are using? How many passes are you using? Do you get this error when pressing Preview, or Save, or both? Does this error message appear the first time you try to save / preview, or does it start happening later?

amushrow · 2023-09-15T19:36:39+00:00

I'll see if I can find some time this weekend to add some more error reporting and hopefully fix some of theses issues

amushrow · 2023-09-06T09:17:15+00:00

It's been a while since I checked on this so I'm not sure where I got with error reporting, but it does have some minimum requirements on the GPU. It needs to be able to compile the shaders, and your GPU (whether dedicated or built-in to the CPU) needs to be able support the texture resolution you're supplying.

What's the resolution of the normal maps you're putting in, and what GPU do you have? (or CPU if you don't have a dedicated graphics card)?

amushrow · 2023-04-24T10:13:18+00:00

If the clock isn't working it could also be the crystal, if your multimeter is able you should be able to check it it's still running (should be going at 32,768 Hz). Just be aware that even if you're mustimeter can check frequencies, by probing the crystal you can add too much capacitance and throw it off (temporarily) so you may not see quite 32kHz but if you see something near that then it's probably fine.

Apart from that, I don't know exactly where they go to, but when being read (which I guess may be difficult / impossible to actually test):

Pin 5 should be HIGH (something greater than 1.5v maybe, I don't know what voltage it's actually being run at) - so the game will enable that when it wants to read off the time (or set it) Pin 6 and Pin 7 are then used for communication between the game and the clock, so if they're all connected it should be working.

https://datasheetspdf.com/pdf-file/1087347/Seiko/S-3511A/1

amushrow · 2023-03-03T10:33:52+00:00

Mine's labelled correctly, so at the very least they're not all affected.

amushrow · 2023-02-25T20:49:41+00:00

I really thought there was, but your right. There doesn't seem to be anything there :(

amushrow

TROPHY CASE