Defeating “TrustedInstaller” with a Command Line Snippet

Here’s a little piece of code to recursively take ownership of a folder protected by “TrustedInstaller” on Windows 7.

takeown /f %1 /r /d y && icacls %1 /grant Administrators:F /t

Save this line in a .CMD file and call it with the directory you want to use it on as the first parameter. You will need to have elevated (Administrator) permission to do this properly.

FPGA/VHDL Video Tutorial Series

I’ve recently started working on an introductory level video tutorial series on digital design using VHDL and FPGAs. I have been uploading my videos to YouTube as they’re completed. I have plans to produce 11 videos in total. As I complete each video, I will update this post with the relevant links.
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Sealed copy of Mac OS 8.1 in original box

Darek over at Emulators.com has a bunch of classic Mac OS system software still in the sealed original boxes! He’s willing to ship them out to you as a trade for a giftcard, which covers the cost of shipping plus a little extra something for his effort. I was able to get a copy of the one version of Mac OS that I had never ran before — 8.1. Pictures are linked below.

• Front
• Back
• Bottom
• Side 1
• Side 2

Modding a DTV Converter Box into a Mini Television

I recently added a small LCD screen to one of those “free” government-coupon DTV converter boxes that I had lying around. It is an AirLink 101 model with both coax and component outputs, and runs off a 12V DC adapter. The first step taken after opening it was to find points on the board that contained the composite video signal and associated ground reference. Luckily, the 3.5mm connector was through-hole and these points were easy to locate. I also located pins for 5V and GND by probing the on-board voltage regulators with my multimeter. Thin wire was soldered onto these points. Next, I tested my work by using alligator clips to source the signals to my small LCD setup. It worked!
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NEZbox External Status Meter for Computers

In my opinion, one of the most useful (not to mention cool) computer mods is the addition of a character LCD to the front of a tower. On and off I’ve considered adding a small status display such as those from CrystalFontz to an empty 5.25″ bay on my computer and talking to it using a program such as the Linux LCDproc or Windows LCD Smartie, but I’ve always avoided it due to price and the idea that putting an LCD on my tower seems to be bad in terms of visibility/placement. Because of this, I decided to look into external solutions such as the $100 Lilliput Mini USB Monitor (feature overkill), or the $50 Pertelian External LCD (grossly overpriced) sold by ThinkGeek. These device have been in the back of my mind for quite some time, and it wasn’t until I stumbled across a very cool mod interfacing an analog VU meter with a desktop computer via microcontroller that I decided to proceed with building my own external status device. Thus, the NEZbox was born.

The NEZbox is a simple ATmega168-based external status meter. I put it together for about $25. The materials used include a Radioshack black plastic project box, a piece of protoboard, an ATmega168 microprocessor, 14.7456MHz crystal (not 16MHz, better for serial com), a USB-to-serial adapter (UART) PL2303 cable, a 4-line LED-backlit character LCD, a 50uA analog meter, a temperature sensor, and some wire and resistors. Later I discovered that my USB ports always stay powered even when my computer is off, so I added an small ON/OFF switch to the back. A Dremel was used to cut out slots for the meter and LCD, and epoxy glue holds them in place.
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Mac Plus Archive (Antique software for use with emulator)

Here is a zipped mirror of the website at http://www.rolli.ch/MacPlus/welcome.html, regarding the historical Mac Plus. It contains legacy software (System 1.1 through 6.0.8, MacPaint 1.4, MacDraw 1.9.5, and a MacPlus ROM image) that may be useful to those studying the old computer. In addition, since the original vMac project is no longer developed, the open source replacement Mini vMac may be useful to those trying to execute the aforementioned software.
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Happy Halloween 2010

Buildin’ an Ice Tube Clock

I just finished building an Ice Tube Clock kit from Adafruit Industries. It looks great and was a lot of fun to put together. Plus, soldering the connectors for the Russian vacuum-fluorescent display tube definitely increased my skill level by a few points. In the near future I plan on adding a light sensitive dimmer to the device. Hooray for open-source electronics! Here’s a nice high-resolution picture of the finished clock for your enjoyment.

Helpful Arduino-as-ISP Commands

So you’re using the Mega-ISP sketch to make your Arduino act as an ISP, which you can then use with AVRDUDE. You can do much more than just burn a bootloader, you can write programs to ATmega168 chips that take advantage of the whole 16KB Flash area (no 2KB bootloader)!

First, be sure to read through the ArduinoISP tutorial to get the circuit wired up correctly. You may also with to consult this ATmega168 pin-mapping diagram.

Here are some helpful commands and settings:

To program your fuse bytes first do:
avrdude -v -v -patmega168 -cstk500v1 -P/dev/cu.usbserial-A600cnPP -b19200 -e -Ulfuse:w:0xE2:m -Uhfuse:w:0xD5:m -Uefuse:w:0xF8:m

I highly suggest to think about your fuse bits before writing them to the chip. You can use an online fuse bit calculator such as this one.

From a post on the Avrfreaks forum:

Note in the ATmega168 datasheet, page 288, that in the extended fuse byte, bits 7, 6, 5, 4, and 3 are all unused. Avrdude knows this, and it intentionally masks those bits off when it reads the extended fuse byte. [...] If I recall correctly, the problem is that avrdude applies the mask at the end of the programming session when it verifies the success of safemode, but not beforehand when it reads the initial value, or something like that.

Arduino’s “unlock” lock bits are: (not typically needed?)
-Ulock:w:0x3F:m

Then, finally, to program the flash memory with your code do:
avrdude -v -v -patmega168 -cstk500v1 -P/dev/cu.usbserial-A600cnPP -b19200 -e -Uflash:w:blink_1MHz.hex

The code in blink_1MHz.hex is from this Sparkfun introductory tutorial.

Texas Instruments F28335 DSP C2000-series Assembler Notes

Memory Sections

.text   executable code       RAML1 (internal DSP memory)
                              starting address = 0x9000, 4K Words
.data   initialized data      RAML2 (internal DSP memory)
                              starting address = 0xA000, 4K Words
.bss    reserved space for uninitialized data
                              starting address = 0xB000

CPU Control Registers

ACC   Accumulator (32 bits) => AH (high 16 bits) and AL (low 16 bits)
XAR0  Auxiliary Register0 (32 bits) => AR0H (high 16 bits) and AR0 (low 16 bits)
   ....up through...
XAR7  Auxiliary Register7 (32 bits) => AR7H (high 16 bits) and AR7 (low 16 bits)
XT    Multiplicand Register (32 bits) => T (high 16 bits) and TL (low 16 bits)
P     Product Register (32 bits) => PH (high 16 bits) and PL (low 16 bits)
PC    Program Counter (22 bits)
SP    Stack Pointer (16 bits)
DP    Data Page Register (16 bits)
ST1,ST0  Status Registers (flags)

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