Hi Exxos, the shifter gets A1-A5 rather than A0-A4, so the odd addresses are already excluded. The shifter does get A1-5 (its just internal bus names which are called 0-4). I think I confused 8bit and 16 here, as each address should be 16bit AFAIK. So I should decode all 32 16bit address lines for ...

The biggest obstacle that I'm dealing with right now is instability. In monochrome, the whole system is reasonably stable, but in colour (50Hz in my case) the length of the video frames are not steady - some are shorter, some are longer. I am working off the theory that this is because of noise in ...

Do you happen to have a part number/digikey link/etc. for the mega bus connector on that adapter?

I do believe however, that this also includes the GLUE logic as it mentions is like ROM & ACIA etc. so likely a lot of this code isn't even needed.. Though if those addresses are removed, it does not look like the MMU does much of anything at all.. It looks almost deceptively simple. In additio...

The & operator in VHDL is the concatenation operator. So chan_amp becomes bits 3,2,1, and 0 from chan_vol plus one additional 1 bit appended to the end. (5 bits in total, with the last bit set to 1) This means 0 becomes 1, 1 becomes 3, 2 becomes 5, 3 becomes 7, etc. Edit: Some more detail. If yo...

... or you could use the extra bits to support 65536 colors similar to how the infamous dual shifter mod mentioned in another thread supports 32768

I see you're using and storing all 16 bits from the data bus, but on the ST, only 9 bits are stored (12 if you want to support 4096 colors like on the STE.) Since you're building this on a programmable device (and not discreet components), couldn't you save some space by only using 12 bit wide RAM b...

I case someone is interested, I found this VHDL implementation of the ym2149: http://www.cpcwiki.eu/index.php/Ym2149

One question I'm asking myself, how is it that when a channel is disabled in the mixer that setting that channel's volume effectively produces a "pop" sound in the output. It's that characteristic which makes digisound possible. But why does the chip do that? I always imagined it's becaus...

Have you considered some of the popular FPGA Dev boards such as the KNJN Pluto boards?

They have a small foot print and both Altera and Xilinx options.

I haven't tried them myself, but I was interested in the one with the HDMI port, although that one does not have 5v tolerant I/O