John's Blog

‘Fixing’ a Commodore 64

A while back I made a nostalgic impulse purchase on eBay and ended up with a Commodore 64 – a real breadbin style one, with no emulation in sight.

This was my first ever computer and I have fond memories of playing countless games, waiting patiently for things to load from tape, and borrowing library books to learn how to code. It literally was my gateway into the computer world.

The machine I bought was a fairly simple bundle – just the computer itself, boxed, with power supply. It arrived a few days later and I was amazed at how small it is.

I spent time cleaning 35 years of accumulated gunk. Everything seemed in pretty good shape, with labels in place, no significant plastic yellowing, and just a few scuffs underneath.

My first problem was that the Commodore outputs an analogue video display, and all my displays are digital. Without a display I can’t see if the machine works.

Speaking of which, I didn’t even know if it worked. The computer was advertised as being untested – a common term for broken – but I’d assumed it just hadn’t been used in 30 years.

Should I ever get it to work and displayed on a screen I then faced the problem of having no media, and no joystick. A problem for another time.

C64 Video Display

As expected, there are devices that convert the analogue signal to digital, and I went with an s-video/composite to HDMI convertor.

The C64 outputs a composite signal, but through a special DIN connector. I found a wiring diagram online, ordered some parts, and built a shoddy adaptor.

Power on – first attempt

Now that I had a compatible display it was time to try the machine out.

First I just plugged it in and switched it on. Nothing happened.

A visit to YouTube showed me that pretty much everything inside the machine can fail. None of it sounded fun. The power supply was the first place to look at as these are notoriously poor quality (I remember warming my feet on mine, back in the day).

Using a multimeter I attempted to read the power coming out of the supply. At first I think I got some values, but on checking again I got nothing so I either fried the supply in reading it, or it was on the way out and died.

I didn’t want to buy an old power supply. I read that the supply is unusual in that it outputs both AC and DC power., This got me to wondering if I could get separate AC and DC power supplies and feed them into the computer’s power socket.

Building a power supply

I found a 5V/1.5A DC supply from a USB hub I had lying around the house. This matches the DC requirements.

I ordered a 9V/1A AC adaptor from the internet – this was much harder to source. Mine ended up having a euro connector, so I also needed an adaptor on top. It’s quite a frankenpower supply.

Both of the power supplies had a 2.5cm barrel plug, so I ordered two barrel sockets as I didn’t want to butcher the cables.

The C64 power is supplied through a 9 pin DIN plug which are still easy to get hold of.

Looking at socket diagrams it seemed simple enough – two pins for DC and two pins for AC. That seemed very manageable.

Here’s the result:

Not bad, although another soldering horror job inside. The cheap component parts didn’t help, melting somewhat.

Power on – second attempt

Now I’ll state that I have no knowledge or experience of electronics, and the double-supply I built may be extremely dangerous, may instantly catch fire, or may somehow create a small black hole.

But it worked!

I plugged everything in – the C64 now sporting 3 power supplies (the video convertor needs one too) – and switched it on. The red LED came on, the monitor went black, and then the pale blue C64 screen appeared with a full complement of memory. Hurrah!

It’s a bit fuzzy and that may be due to the video cable I made. I’ll try another soon.

I don’t know if the SID chip works, and I don’t know if it can play a game. There are devices you can buy that take an SD card full of files and emulate a disk drive to the C64. That’s something for another day.

My joy at making something that worked was a little tempered when I reassembled the C64 and managed to crack the brittle plastic with the screws. Also, I have a spare screw I can’t find a home for. Annoying.

Fixing Sony A7 LCD delamination

I’m a big Sony camera fan, and I’ve been using an A7 for the past few years. Recently I noticed the rear LCD was showing a lot of patchy discolouration.

It was starting to get very noticeable and distracting, and was only getting worse.

It turns out the camera has a built-in screen protector, and it’s this that is prone to delamination – the LCD underneath isn’t affected. Fortunately it’s possible to remove the protector.

The original is stuck in place with some fairly strong glue and I used a razor blade with some gentle pushing to lift a corner. From there you can peel back just enough to get your fingernail under, and the rest can be worked free. Make sure not to pull the LCD off!

Note the mark in the top right corner is glue from the protector. This wiped clean with an alcohol wipe.

Once removed I replaced it with an Afunta A7 screen protector. It’s a bit thicker than the original (it says it’s actually glass), but fits nicely. The end result is a big improvement:

Super Nintendo Mini Classic, for kids

I bought a SNES Mini Classic recently.

The original wasn’t that popular when I was young – more of an American thing I think – and I didn’t know anyone with one, so I was very curious. The closest I got as a kid was The Great Giana Sisters on the Commodore 64 (a Super Mario clone).

I also wanted to see if I could get my daughter interested in some simple video games, outside of the many cooking/hairdressing/simple tapping games she has on the iPad.

It is easy to emulate older systems, but I wanted a self-contained box that could be plugged into the TV, and that my daughter could use. The mini classic fits the bill perfectly. It’s got two nice colourful controllers that are ideal for small hands, and a simple on/off switch and reset button. The European version is very friendly looking, unlike the ugly weird American one.

She’s loving it so far, and has even taken to watching people play Mario games on YouTube (I’m going with it being a good thing).

One thing I quickly realised is just how brutally difficult older games are, and some of the bundled games are very unforgiving for kids. Kirby’s Super Star has become the favourite, followed by Donkey Kong Country and Super Mario World.

Some of the games are also very verbose, and some of them I can’t figure out what I’m supposed to be doing (Final Fantasy & Secret Of Mana I’m looking at you).

It’s been fun playing the games with her so far, and as a bonus, her geek points are rapidly increasing!

Speeding up a Synology rebuild

After purchasing a Synology NAS I inserted a bunch of drives and left ‘expanding’ overnight.

When I came back in the morning it had gone from 2% to 5% complete – about 95% less than what I was hoping.

I discovered that you can SSH into the box and check the status of the rebuild with:

cat /proc/mdstat

This showed that I had another 14 days left. Hmm, I don’t think so.

After some poking about I discovered it defaults to a strangely small 256 byte cache size.

There were a lot of posts on the internet about changing this value in /sys/block/md3/md/stripe_cache_size, but this failed with a permission problem. Maybe this applied to older versions.

Instead you can edit:

/etc.defaults/synoinfo.conf

And add the line:

md_resync_cache_size="16384"

It took a few minutes for this to be picked up and then the rebuild time decreased to 14 hours. Much more acceptable.

I tried some larger cache size values but they didn’t make any difference.

Clearing Chrome’s DNS cache

If you ever need to point a domain name at an IP address, for sandboxing during development, or for whatever reasons, then Chrome can be a real nuisance. It seems to cache the domain name and refuses to use your new IP address.

Recent versions supposedly monitor /etc/hosts, and if you view the DNS cache this seems to be true.

chrome://net-internals/#dns

However it can still be stubborn about actually using the new IP. After some digging I found that clearing the socket pool usually does the trick.

chrome://net-internals/#sockets

Certainly beats waiting until Chrome finally gives up the old values.