CMOS vs TTL: What are logic families?
June 26, 2022
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.
Ian’s projects
June 26, 2022
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.
June 19, 2022
We connect an HD44780-powered LCD character display to the circuit and play a simple text animation from the program ROM.
May 15, 2022
March 11, 2022
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.
February 18, 2022
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.
December 20, 2021
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.
December 5, 2021
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.
November 22, 2021
We add three more 74LS163’s to our counter to make a 16-bit address register for our homebrew CPU project.
November 15, 2021
We connect our clock circuit to a 74LS163 synchronous binary counter and see how to count, reset and load values into the counter.
November 12, 2021
November 9, 2021
In this video we create a clock circuit with a 555 timer in astable mode, and use it to blink a green LED.
November 5, 2021
November 4, 2021
October 19, 2021
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.
January 5, 2021
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.
December 29, 2020
November 17, 2020
Hello! Content from the old excess.org site will be migrated here over the next few months. Thank you for stopping by.
August 4, 2017
CKAN’s datastore_search
now comes with format options and is up to 17x faster.
This article covers:
TL;DR:
datastore_search
is faster with no other changes requireddatastore_search
client code to use one of the new records_format=csv
and/or include_total=false
options to make it much, much faster