Week of the 05/06/2024 - #19



  • Telephone switch motherboard found
  • Database for electronic components
  • Reading manga on the kindle
  • Beautiful LaTeX mathematics thesis

Telephone switch motherboard found

I found the main circuit board of a telephone switching system. I inspected the chips to see what they do and which I can try to pull out to re-use. Here is the list:

  • HD63B03XP: This is the microcontroller and is basically compatible with the HD6300 cpu’s.
  • LC366BL-10: 64K RAM memory chip
  • UM23C512: Is probably a 64k x 8bit mask programmable ROM. Found a Datasheet for the HT23C512 which is probably the same thing from another maker.
  • MSM6242B: The MSM6242B is a silicon gate CMOS Real Time Clock/Calendar for use in direct busconnection Microprocessor/Microcomputer applications. An on-chip 32.768 KHz crystal oscillator time base is divided to provide addressable 4-bit I/O data for SECONDS, MINUTES, HOURS, DAY OF WEEK, DATE, MONTH and YEAR. This chip is also used on the Commodore Amiga hardware.
  • LC7385: The board has 2 of these. They are decoders for the “16 DTMF digits used in telephone systems”. They basically can identify and decode the standard tones used on old telephone systems. They use a 3.579545 MHz crystal which I can use for my OPL-2 synth board.
  • UM95089: A DTMF generator designed to implement a dual tone telephone dailing system. Also uses the 3.579545 MHz crystal.
  • SVM 7860c: The SVM7860C Series CMOS IC produce melodies or alarm tones from a preprogrammed ROM. The ROM has a capacity of 127 words and can store 1 melody from two sound sources with an envelope.
  • M4021001BP: The board has several of these chips. They are 4x8 crosspoint switches with control memory. Basically you specify a 5bit number which connects on of 4 i/o pins to one of 8 i/o pins.
  • D4066BC: There are 3 of these which are quad bilateral switches. Basically an eletronic relay.
  • JRC 4558D: There are 6 o 7 of these ICs which are dual operational amplifiers.

I have the datasheets here

Blood on the tracks manga

Database for electronic components

While trying to identify the different components on the motherboard I realized it’s not easy to find the datasheets and what each IC does. I think it would be nice to have a centralized, open source database of electronic components. I googled a little and found only one good project but seems somewhat abandoned. I will add here links to new items if I find them.

  • chipdb - Github repo with YAML files which give you information for each IC. It’s not very big but it’s the best I found.

Reading manga on the kindle

Blood on the tracks manga

Every once in a while I read mangas and it would be great to do it on a Kindle. Kindles are ideal because they have a black and white display and most mangas are in b&w so you are not loosing much. Also the size is about the same. I have a Kindle Paperwhite, 11th generation. The resolution is 1236 x 1648 and 300 PPI which is more than enough to display mangas. To create .epub files from .cbz mangas I found KCC: a.k.a Kindle Comic COnverter. It is has lots of options to set what resolution you want to use, it reduces the size considerably (in one example from ~130MB to 32MB) and can also be configured to read from left to right. To send it to the Kindle I usually do it over email but these manga are consdierably large so I used the sendtokindle link.

  • KCC - KCC (a.k.a. Kindle Comic Converter) is a comic and manga converter for ebook readers.
  • Send to kindle.

Beautiful LaTeX mathematics thesis

Gilles Castel has been using LaTeX during his studies of mathematics for taking notes and creating beautiful lecture notes done very efficiently. He has several blogposts which explain his tricks to be able to do it while taking classes. His thesis is even more impressive than his lecture notes. You can find it on Github and he encourages everyone to use it as a template. Here I include some links to his stuff and a couple of pages from the thesis.

Master thesis sample page 1 Master thesis sample page 1