In this video we replace our clock’s 4011 CMOS Quad-NAND gate IC with a TTL equivalent and discuss compatibility between different logic families.

We connect an HD44780-powered LCD character display to the circuit and play a simple text animation from the program ROM.

We build a larger address register and use it to test an SST39SF040 512k flash chip.

This is part two of a two-part series. Read part one here.

In this post we use Python to encode the full Bad Apple video (3m39s) into 32 kilobytes. Our playback hardware has no CPU so our video “compression” is limited to the features of our HD44780-powered LCD display.

We create an illusion of a full bitmap display by carefully juggling 8 CGRAM characters across the 8 x 4 video area and lean on LCD display persistence.

This is part one of a two-part series. Read part two here.

This post covers how we interface a 32K EEPROM, a clock and an address register to a 20 x 4 LCD character display module and use it to play a video. We “decompress” the video by expanding our 8-bit data stream to 9 bits for playback in hardware. There is no CPU or microcontroller involved.

We complete our clock module by adding a halt signal and test it with our address register. Now our (future) programs won’t have to run forever.

We add a reset circuit to our clock module that resets our address register to “0” on power-on and when a button is pressed.

We add three more 74LS163’s to our counter to make a 16-bit address register for our homebrew CPU project.

We connect our clock circuit to a 74LS163 synchronous binary counter and see how to count, reset and load values into the counter.

We add a potentiometer and a single-step button to our clock circuit.

In this video we create a clock circuit with a 555 timer in astable mode, and use it to blink a green LED.

This video introduces the first milestone for our homebrew CPU project.

• Bank Python
• Excalidraw

This youtube tutorial covers interfacing with an LCD2004 20x4 LCD Character Display module with an HD44780 controller using only switches and simple components on a breadboard.

ckanext-scheming 2.1 now support Datasets with repeating subfields and repeating text fields. Repeating subfieds support custom snippets and validation just like regular fields.

This work is inspired by the excellent ckanext-composite extension and replaces ckanext-repeating repeating_text fields.

You must be using CKAN 2.8 or later and a custom IPackageController plugin to index datasets with repeating subfields.

• NumPy Illustrated: The Visual Guide to NumPy
• Half-Precision Floating-Point, Visualized
• Johnny•Decimal
• PostgreSQL index optimizations
• “A Mind is Born” 256-byte demo

Hello! Content from the old excess.org site will be migrated here over the next few months. Thank you for stopping by.

CKAN’s datastore_search now comes with format options and is up to 17x faster.

This article covers:

• new total row calculation
• new result generation
• new record formats

TL;DR:

1. Use CKAN 2.7 or later and resource views and other code that uses datastore_search is faster with no other changes required
2. Update your datastore_search client code to use one of the new records_format=csv and/or include_total=false options to make it much, much faster