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Hardware

Expansion card: YM2151 Audio

This sound card is based around the Yamaha YM2151 8 channel FM synthesiser. It was used in some Yamaha synthesisers and systems such as the Sharp X68000 and ...

Expansion card: TMS9918A

When I ordered the new PCB for Y Ddraig, I also ordered some additional expansion card PCBs. A couple of these I had made previously and just moved the desig...

New PCB for Y Ddraig

One of the things that I have been working on is a new circuit board design for Y Ddraig. Superficially the board design is much like the previous revision. ...

FPGA Video card update

I’ve been working on several areas on Y Ddraig the last couple of months and I have been making some good progress. I’ll be posting some updates on some of t...

FPGA Video card CPU access

In my previous post, I had the VGA output working and was able to display several test patterns. I briefly mentioned that I could read data from the SRAM on ...

FPGA Video card testing

The FPGA video card has been built up. A couple of mistakes in ordering the parts so I ended up with a couple of capacitors that have the wrong footprint but...

FPGA Video card

Now that I have two expansion boards working successfully with Y Ddraig, a sound board based on the Yamaha YM2151 and a video board based on the Yamaha V9958...

Working board and audio

Bringing up the new board this time was pleasantly straight forward. I did have one mistake on the design where the enable lines for the data bus buffers we...

Y Ddraig redesign

It has been quite a while since I have posted any updated here. Some of the lack of progress was down to working from home. While I thought that this would g...

SN76489: Success and Failure

Trying to get the SN76489 working has been an interesting exercise and a good example of why it is important to read datasheet with great care. Initially I ...

A small update

It’s been a while since I’ve done any work on this project. I was going to build, or at least part build a second board to see if I could get the V9990 worki...

DRAM and IDE

The last couple of weeks have mostly been spent working on improving the monitor code but there has been some progress on the hardware side as well. Both th...

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Software

DRAM and IDE

The last couple of weeks have mostly been spent working on improving the monitor code but there has been some progress on the hardware side as well. Both th...

YM2151 Sound

Getting the sound working turned out to be easier than expected and managed to get the YM2151 playing music fairly quickly. To get some music playing I used...

Monitor ROM

Y Ddraig now has a ROM based monitor program to speed up development and debugging. It’s based on the zBug monitor by Wichit Sirichote. The ability to...

It’s Alive

A working serial port! Tracking down the problem Fixing this involved a bit of head-scratching when trying to track down the problem. All logic signa...

First Software

With the hardware assembled and the CPLD programmed it’s time to start writing some code to test and see if the hardware is working. The first program to te...

Address decoding

Before writing any software for Y Ddraig the CPLD will need to be programmed. The CPLD being used here is a Xilinx XC95108 and it is responsible for the addr...

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Design

PCB Populated

It’s been a while since any updates but some progress has been made. I’ve populated one of the PCBs and powered up the board. All seems fine so the next step...

PCBs delivered

I have recieved the new PCBs. Ordered from https://jlcpcb.com/. Initial inspection shows the boards seem to be fine. Next step now is to start building up o...

PCB design re-started

After a long break from the project I have decided to restart the design making a few changes to the board.

Problems with the PCBs

Started to assemble the first circuit board and run into some immediate problems. It turns out that there is a short circuit between the 5V and GND planes on...

PCB design completed

The schematic design has been done and after many hours routing tracks the PCB layout has been completed and ready to be sent off for manufacture. ...

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PCB

PCB Populated

It’s been a while since any updates but some progress has been made. I’ve populated one of the PCBs and powered up the board. All seems fine so the next step...

PCBs delivered

I have recieved the new PCBs. Ordered from https://jlcpcb.com/. Initial inspection shows the boards seem to be fine. Next step now is to start building up o...

PCB design re-started

After a long break from the project I have decided to restart the design making a few changes to the board.

Problems with the PCBs

Started to assemble the first circuit board and run into some immediate problems. It turns out that there is a short circuit between the 5V and GND planes on...

PCB design completed

The schematic design has been done and after many hours routing tracks the PCB layout has been completed and ready to be sent off for manufacture. ...

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CPLD

First Software

With the hardware assembled and the CPLD programmed it’s time to start writing some code to test and see if the hardware is working. The first program to te...

Address decoding

Before writing any software for Y Ddraig the CPLD will need to be programmed. The CPLD being used here is a Xilinx XC95108 and it is responsible for the addr...

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Debugging

It’s Alive

A working serial port! Tracking down the problem Fixing this involved a bit of head-scratching when trying to track down the problem. All logic signa...

First Software

With the hardware assembled and the CPLD programmed it’s time to start writing some code to test and see if the hardware is working. The first program to te...

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Errors

Problems with the PCBs

Started to assemble the first circuit board and run into some immediate problems. It turns out that there is a short circuit between the 5V and GND planes on...

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Music

YM2151 Sound

Getting the sound working turned out to be easier than expected and managed to get the YM2151 playing music fairly quickly. To get some music playing I used...

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