I built a speech synthesizer board for the RC2014 The speech synthesizer IC that I chose is the SP0256A-AL2. One of my reasons for choosing it was that it seemed plentiful on eBay. They’re all fakes though, every damn one of them on eBay, so far as I can tell. 🙁 Fortunately, there is a …
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SP0256A-AL2 speech synthesizer chips: Genuine vs Counterfeit.
All I wanted to do was build a speech synthesizer… To make a long story short, I’ve ordered chips from three difference China eBay sellers, and have received three different sets of chips that don’t work right. The first set of bad chips Here’s the first one: This one actually turned out to be an …
Read MoreZ80 Retrocomputing 7 – RC2014 DAC (Digital To Analog Converter)
I build a digital to analog converter for the RC2014: [TODO: insert video here] Digital to analog converters are useful for interfacing microprocessors to analog devices. They typically take a digital value of a fixed number of bits (in our case 8 bits) and convert it to an analog voltage or current. The DAC presented …
Read MoreZ80 Retrocomputing 6 – RC2014 TIL311 Front Panel Board
I was so pleased with the Bus Monitor board that I decided to also build a “front panel” board. [TODO – Insert video here] This front panel board also uses TIL311 displays. Design Here is the schematic: If you haven’t read my other posts on the Z80 retrocomputer, please start with the first one, as …
Read MoreZ80 Retrocomputing 5 – Single Stepper for RC2014
In this blog post, I design a single step module for the RC2014. [TODO: Insert Video Here] If you haven’t read my introduction to retrocomputing yet, then please start there, as it describes the Z80 platform that I’m using. The single step module is an alternative to the bus supervisor that I designed in the …
Read MoreZ80 Retrocomputing 4 – Bus Supervisor
This is the fourth in my series of Z80 retrocomputing blog posts. For background, I suggest starting with the first post. So what exactly is the purpose of the bus supervisor board? I wanted to do some assembly language work on the RC2014 Z80 Retrocomputer, and I examined several options: I could program an EPROM …
Read MoreZ80 Retrocomputing 3 – Bus Monitor Board
I wanted more lights on the retrocomputer, so I decided to add a bus monitoring board. For a brief introduction to my retrocomputing posts, please start at the first one. So what exactly does the bus monitor board do? It monitors the Z80 address and data buses and displays the current values on those buses …
Read MoreZ80 Retrocomputing 2 – Real Time Clock for the RC2014
I developed my first add-on board for the RC2014. This board is a real-time clock and an 8-bit output port. I’ll use it to build a Nixie Tube Clock.
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