A blog about my projects!
Sometimes I need to transfer text from my Android smart phone to my Linux PC. There are many many ways to do this I guess, but I wanted something easy under my control. All phones have web browsers, so I settled on the classic solution of simply running a PHP script served by an Apache HTTP server. The script just displays the input form, and on a POST request saves the contents to a timestamped…
I saw this video by Necroware earlier, about the possibility to extract the contents of the RTC modules found in older PCs. I have tried it myself and it is indeed possible to use hot air to weaken the resin and break off the external casing. This is an alternative to drilling holes in the side of the RTC module as shown in an earlier post to expose the battery contacts.
Around 18 years ago I made a program to control a 'Cooltek' LCD display over the parallel port from a PC. Since parallel ports are hard to come by these days I had to make an update. I happened to have a Arduino Nano R4 lying around so I decided to use that one. Many of the Arduinos, including the Nano R4, uses 5V GPIO levels which makes things simpler since no level shifters are needed to…
I bought a Lode Runner cartridge for the Sega SG-1000 while on a trip to Japan. Testing the cartridge back home yielded no results, just a black screen. Looking closer at the edge connector at the cartridge, the pins were completely black. Using isopropyl alcohol or contact cleaner on them would just result in black sot. I am wondering if they used silver plating on the pins, which could cause…
I have a Sega SG-1000 II that I have modified to work with composite video and audio. Originally it only supports RF output and only on Japanese channels, which makes it impractical and hard to use. My changes are based on the 171-5141 revision of the PCB, which is supposedly the first revision, with the TMS9918 video chip. According to the datasheet for the TMS9918, it can drive a composite video…
Once again a dead RTC battery, but this time in a 16 year old Acer Veriton N260G NetTop PC. The old battery is an encapsulated CR2032, but with 3 leads instead of the usual 2. Actually two of the leads go to the negative side and one lead to the positive side:
Although I added support for the piezo speaker some time ago in an earlier version, it did not sound very nice, especially if trying to play back any music. The challenge is to try and feed the audio callback at an exact rate, but this has now been solved by letting the audio callback itself control the speed of the entire emulator. From now on, if piezo audio support is compiled in, the SDL…
There exists a somewhat famous video which has a 'monochrome' animation and music made by Alstroemeria Records based on the Touhou Project.
I have added Unicode text support to my tmce64 emulator and bumped the version number to '0.5'. This is to support drawing characters in the terminal that resembles PETSCII instead of just approximate ASCII. There are support for two different variants of this. The first variant is using symbols from the standard Unicode blocks 'Box Drawing', 'Geometric Shapes', 'Block Elements' and 'Symbols for…
I got a .no domain now, so the web hosting has been moved yet again after being around 6 years at the other place. It is also no longer relying on PHP and using static HTML pages instead, which already used at the https://kobolt.github.io/ mirror.
I have made a minor update to my a2c emulator. The version has been bumped to 0.2 and can be downloaded here or from the GitHub, GitLab or Codeberg repositories.
I started a new emulator experiment, this time a PDP-11. The goal is to eventually be able to run Unix but that requires additional emulated hardware support. This first released version is able to run the original Tetris which is good enough for now. The result is an emulator that is kind of like a PDP-11/40, with the EIS and FIS instruction sets, but without the MMU support.
I had trouble with a PCI express parallel port card in a modern Linux box not behaving as it should, so I decided to make a test setup. It is based on loopbacking 5 data output signals to 5 status input signals, which is the same as was done in some older DOS software.
This is kind of like a follow up on the CHIP-8 Interpreter for Epson HX-20 that I posted about earlier. To help with development of that implementation I also made an implementation in C using curses that can run in a Linux terminal.
In order to simplify the creation of audio files that can be played to a Epson HX-20 I have reverse engineered the format used for binary files and created a C program. The binary files are meant to be played back when in the MONITOR and not in BASIC and they contain just raw data to be loaded at different memory addresses.
CHIP-8 has been ported to several platforms, but I decided to port it to the Epson HX-20 since the hardware is capable enough. The LCD screen is 120x32 pixels so it can fit the CHIP-8 screen of 64x32, and 16K of RAM is sufficient for both the interpreter code and the CHIP-8 4K memory space.
This is a new version of the Python Image Viewer posted earlier. It has now been updated to be Python 3 compatible and there is a couple of new features. The first feature is resizing of all images to the same resolution. The resolution is provided by an argument or will be 800x600 by default. The second feature is an extra button to browse to a random image.
There is a serial terminal emulator program for the Apple II called ASCII Express which can run in 80 columns text mode. Also interesting is that it can emulate several real terminals including the DEC VT52.
Earlier this year I started coding on a Motorola 68000 emulator. The original plan was to just add an MMU and do some minor changes to convert it to a Motorola 68010 after the base 68000 work had finished. But I discovered that the 68010 is not that widely supported software wise compared to the later Motorola 68020 which even more advanced. So instead I focused on pure 68000 support and adapted…
As part of restoring an Apple IIc I decided to test the RAM since I've experienced some unexplained freezing when testing.