Today I received a ZXpand with AY sound add-on.
This is a really useful SDcard device for the ZX81 made by my pal Charlie Robson.
Havent had a chance to mess around with mine today but ive used one at RCM and have been most impressed.
Ill post more on it when I get time over Christmas
Taking my new found interest in all things Sinclair a little further I have got hold of a copy of this book.
From what little Ive read so far its seems very interesting and about my level too.
So I made my first FPGA program for the LCD on the dev board. I found this amazingly hard work as the whole VHDL programming seems unnecessarily difficult and good tutorials are limited and undescriptive.
Still, here it is:
Got myself a couple of these SID replacements today.
I first saw them around April this year but have not been available to buy until now.
As you can see they are around the same size as the original and my first impressions are very good.
There are 2 jumpers on these.
The top one needs to be removed for older C64’s. It has something to do with resistor R3 and bring the volume level up.
The lower one is to switch between 6581 and 8580 emulation. A switch could also be added here to switch between then on-the-fly.
To test these against an original 6581 I used the SIDPlay program running from SD2IEC and fed both the samples into a PC to record them.
The most noticeable difference for me is the volume level on the original is far higher and I also think its a better, cleaner sound BUT as the SID chips are now going for stupid money by opportunists on eBay then this is a really nice alternative and one that will come in very handy in the future for many people.
Here are the .WAV files. Ive not converted these in any way, they were taken using Sound Recorder app that comes with Windows XP. The samples were taken directly after each other and no settings were altered at all.
So my ZX81 ROM is apparently too slow to take advantage of my ULA so that means I needed an alternative. Unfortunately, as with the breadbin C64’s there is no EPROM alternative for the 2364 ROM but there is also no room in the ZX81 case for an adapter to fit properly.
Enter the ROM-EL 2364 from Retro Innovations.
This is a modern day solution for those old ROM’s and can be made switchable with a little extra work.
The only problem is an adapter is required in order to actually program the replacement. As the one I made was a complete hash I wont be taking any pictures of it but it served its purpose and now I have a switchable ZX81 BIOS.
My 81 is starting to look less like the original and more like a modern rehash but its working just great.
