Analog and Digital, Notes and Thoughts
I’ve noticed that brute force is used in most of the videos on Youtube which show how to shuck the hard drive of a WD My Book. This isn’t necessary if you know where to apply pressure on the case. I’ve made a short video myself showing how to open the case without scratching it or breaking the tabs.
Don’t ask why but I find it interesting to grow plants others would consider to be weeds… which must be pulled out. This time (besides the obligatory Arabidopsis thaliana 😉 ) I’m cultivating Cardamine hirsuta (aka. hairy bittercress / Behaartes Schaumkraut). I’ve found it in our garden. Nice.
I’ve just seen how much time has passed since I’ve updated my website. Time to add a few projects I’ve been working on over the last year…
Got a few fidget spinners that were sorted out due to defects. Repaired most of them an played a little with them. In the end I did not have any use for a few dozen figet spinners so I donated them to a charity tombola…
But I kept a few of the LED circuits… just because they were blinking… you know…
I did not post anything for quite a while… we bought a house and moved into it. This consumed most of my spare time and my ‘hacking capabilities’ during the last few months. But the good news is: I’ve now got a whole room in the cellar which I’m currently turning into a hacker lair / electronics shop without having to care too much about the the WAF.
I just just returned from a business trip to the US and wanted to ‘report back’ with a nightly impression of New York / Manhattan. (Please forgive the low quality as the photo was taken with my smartphone from the airplane window.)
I’m currently working on a custom development board, based on a quarter of a century old microprocessor, the Sharp LH5801. This microprocessor is the heart of the Sharp PC-1500(A) Pocket Computer, also known as Tandy TRS-80 Model II.
I’ve got plenty of documentation on the processor and the Sharp PC-1500, but what I did not have was a spare processor to play with. Recently, I got hold of a dozen of them, so no excuse anymore for not playing with them. 🙂
I started the design process by measuring out the package size in mm and wondered about the strange results I got… Well the size of LH5801 package is – bang on – 0.7 inches. It also has an odd number of pins for such a package size: 76 pins. Both make it pretty impossible to use the standard footprints provided by various package libraries. At least a short round of googling for packages for Eagle CAD or KiCad was unsuccessful.
So I had to design my own footprint which was smoother than expected. I used a already present layout with the correct footprint pitch and adapted copied/adapted the pins.
The part was made with KiPart (based on a CVS table). The pin description and layout was taken from the Sharp PC-1500 Technical Reference Manual.
The resulting KiCad part and footprint is in my Sharp PC KiCad Library at GitHub.
I was able to get my hands on a few Sharp LH5801 microprocessors. They are new old stock (NOS) from Tandy (i.e. were meant for TRS-80 PC-2 computers).
I’m planning a new project with them, but not yet telling what it will be… 😉
…so stay tuned.
That was a really nice Sunday… 🙂
At work we have a KVM over IP switch from Inter-Tech, a KVM IP-KVM101. It is really a small and versatile device that, in combination with 16-port KVM switches, allows us to control a complete rack with test hardware.
The KVM switch provides a web interface with a Java Web Start application for remote access. But the latest browser security updates disabled and removed the Java Web Start support . This move was announced quite some time ago (Oracle White Paper). Still, the vendor of the KVM switch, Inter-Tech, was not able to provide a valuable solution to cope with this problem.
After a bit of Googling I found an Amazon review about this particular KVM switch where the reviewer stated to have installed the firmware from another brand, the LINDY KVM over IP Switch. The LINDY switch looks identical (besides a different sticker) and – even better – their latest firmware provides a VNC server. This would allow us a browser and even operating system independent access to the KVM.
Continue reading “KVM over IP Switch: Cross-vendor Firmware Upgrade via hidden Option adds VNC Server”
The 80’s called: they want their audio back…
That’s what happens when you’re drinking a few beers and being in a nostalgic mood: Already over a year ago I had designed a generic Covox Breakout Board (Wikipedia link) based on an old well established design.
The whole design is based on two TTL ICs (74HCT373 and 74HCT164) and an R-2R resistor ladder (7.5k and 15k Ohm). The result is a simple DAC with 8 bit parallel and serial input and a few control pins. I’ve uploaded the PCB (back then I still used Eagle Cad) and the Gerber files to my Github Covox Repository.
Sure, I could have taken a cheap audio DAC, address it for example via SPI, and let the dedicated chip do all the heavy lifting. But that would not have been half of the fun of designing the board and (bit)banging the audio signal… 😉
The design is pretty generic and when I built it I thought I could use it in combination with a Sharp PC to generate audio output. I started with a few lines of code, but in the mean time other private tasks became more important. So I’ve reduced my testing of the Covox card to connecting it to an Arduino board and output simple (square and saw tooth) waveforms on my oscilloscope. Maybe if there is enough interest I will try to create a video with some mod-tracker like audio output…