Reviving a classic

I recently bought a couple of ZX Spectrum 48k computers from eBay. My first computer was a Spectrum (speccy) 48k+.

One of the 48k's is in great condition, the other, while working fine, was a little shabby, though not too bad. The keyboard sensitivity was not 100%, but OK.

I decided to clean up the shabby one.

It had been repaired, at least twice, with little warranty stickers added. This little speccy was in use until at least 1992.

Keyboard

Removing the keyboard was a pain. The ribbon cables for the keyboard membrane were stuck in the connectors. It was almost as if they had been glued, but is most likely due to the material degrading over time. The cables were very brittle and tore as I was removing them.

Removing the broken cable was also a bit of a pain. I cleaned out the connectors.

This one little screw holds the circuit board onto the bottom of the case.

Quite a few of the RAM chips, including the video DRAM are socketed, and do not match the originals. These must have been replaced.

As the metal faceplate was already loose it easily came off, revealing a keyboard with years of dust, but otherwise OK.

The keyboard popped off easily to reveal the membrane.

I found a retro site selling parts, including brand new faceplates, keyboards and keyboard membranes.

http://www.dataserve-retro.co.uk/

You can even get replacement kits for the little rubber feet of the ZX81, 48k and 48+.

After cleaning up the top of the case, attaching the membrane and keyboard was easy.

Then the faceplate. It's not stuck down in this photo.

The new faceplate isn't quite as nice as the original. The font isn't as bold, and the colours less saturated, with the result that the keywords are less easy to make out. Also, the spectrum logo is a bit off. However, more importantly, the new faceplate is a perfect fit.

Video

Now time for the video modification. Unlike more expensive computers of the era, the speccy 48k did not include output for a monitor - neither RGB nor composite. The only output was a UHF/VHF RF signal for use with a TV. This is a pain, as the frequencies used are now allocated for other channels. So, the speccy cannot be used well as-is with a TV or TV capture card. Fortunately, the composite video signal is fed into the modulator, and a simple modification is all that is required to get a composite signal output. The original TV out socket is a standard RCA socket, so "normal" RCA composite cables can be used without changing the socket.

I followed the instructions here:

http://womblesretrorepairshack.blogspot.com/2008/11/zx-spectrum-composite-video-mod.html

Popping off the top of the modulator box shows a resistor connected to the centre pin of the TV out socket. This carries the RF output signal.

The side view shows the composite video signal being fed into the modulator on the left, and +5v power on the right.

Desoldering these three is not hard, even for me.

Then, all that's required is to connect the composite signal to the centre pin of the TV out socket. The modulator shield is grounded, so no change is needed here.

Not the world's best solder job, but it will do.

I quickly hacked up a composite video cable and... it didn't work. It didn't work because my PSU was set at 6v, not 9v. Doh.

Video quality is not great. There are some more hacks to improve video quality, and even provide S-video output, at this site:

http://user.tninet.se/~vjz762w/rebuild.html

I'll probably get around to doing these one day.

Tapes?

I think the last time I used a cassette was copying a Japanese language test (to MiniDisc!) back in 2001. It's the 21st century and I don't really plan on reliving the "fun" of tapes. So, I bought a DivIDE interface from this guy:

http://www.lotharek.pl/

It works great. The default ROM is FATware which allows loading snapshots (SNA, Z80) and emulating tapes (TAP). It would be even better if it provided the ability to save snapshots. This and more are provided by ResiDOS, but this requires more RAM than the 8k the DivIDE interface provides. DivIDE+, Spectranet and the ZXCF and similar interfaces are all capable of running ResiDOS. As far as I'm aware there is nowhere to buy these pre-assembled. The ZXMatrix looks far, far beyond my abilities to build. The spectranet interface is still under development and looks very promising.

I also bought the Garmin "iMic" USB audio interface, so that I can save to/load from my iMac if necessary.

The finished article. Ready for another 30 years. Maybe.

Optics pr0n

Borg have some pretty pictures with Fluorite crystals.

http://www.tomytec.co.jp/borg/world/blog/2011/06/50fl20110603.html

http://digiborg.wordpress.com/2011/06/02/fluorite-crystal/

dyndns suckage

I registered my dyndns domain "waypoint.homeunix.net" many, many years ago. After dyndns changed over to charging for services that used to be free, I got an email explaining this. Fortunately, my domain is always kept alive, so I even kept the wildcard option, which is now pay only.

Sometime last month, my account was deleted and the whole *.homeunix.net domain removed. I got no notification of this. OK, it's free so I can't complain much, but dyndns used to proudly proclaim it was free and always would be.

I'll now most likely just use a free wordpress.com account, or go back to blogger, maybe even iCloud. I have to fix my blog before exporting it. I'll also probably not bother with my own domain that forwards to the blog or any other hosting.

M45 wide field and 100% crop

The result of stacking after processing, but before cropping. Processed to enhance the stars.

There is still some vignetting despite the use of flats, and some banding from the sensor is visible as I stretched the image to pull out the nebulosity.

The stars were trailed due to poor alignment. "Fixing" them in Photoshop has helped, but they are still not round.

M45: The Pleiades

The Pleiades or Seven Sisters, number 45 in Charles Messier's catalogue of nebulae is a well known asterism and nebula in the constellation of Taurus (the Bull) and is visible in the autumn and winter skies. I took this image at the end of last year in Langkawi in Malaysia.

Olympus ZD-150/2 lens @ f/2.0 on E-620. Kenko SkyMemo-R mount. Pre-processing in IRIS, post-processing in Photoshop CS5.

I'm still learning how to process images. It's hard.

Things are Awesome

So a couple of weeks ago I was sitting have breakfast and browsing the web on my iPad, when the (free!) 3D Sun app decided to interrupt to tell me about a large Coronal Mass Ejection on the Sun. I then switched to this app and was able to see photos of the Sun, in various wavelengths including X-rays. These photos come from STEREO, which allows us to see more than one side of the Sun. I was also able to download videos of the CME.

Think about that. I got notification of a huge event (and I mean huge - many times the size of the Earth) on the Sun that we didn't even know about until relatively recently. I'm not some astrophysicist at NASA or another national space agency, I"m not even a researcher in astronomy in general. I'm just a guy with an app. An app that allows me to see videos in fecking X-rays of the Sun. The views from the telescopes on two spaceships are automatically combined to form an image on a globe that I can rotate and look at as a 3D object. All of this while sitting at home drinking coffee and eating toast.

How awesome is that?

I am typing this on my new (shiny shiny) MacBook Air, while my Roomba (a robot) is hoovering the apartment. The Roomba  does this everyday at 8:00am and then goes back to its charging bay ready for the next day. You probably didn't stop to think about the "browsing the web" phrase in the first sentence. From my computer I can keep up with events and current research from all over the planet, see videos and photos from that people I don't know from all over the world. Likewise I can easily share photos and videos. In addition, I have available to me a large portion of the world's knowledge (for good and bad). I can do all this while enjoying a coffee without leaving my chair.

How awesome is that?

Not only can I do all of this, I can look forward to a much longer, healthier and happier life due to improvements in medicine and healthcare.

This is a few examples of "teh awesome". This is the best time to be alive.

Yay for science, yay for engineering, yay for geeks.

We're screwed when Peak Oil kicks in, though.

Hillis Plot

In case you've not yet come across the truly awe-inspiring Hillis plot from the group at UT, here it is: http://www.zo.utexas.edu/faculty/antisense/DownloadfilesToL.html

There's a blog entry with a good description here.