I have spent a large part of the last few months packing kits, and putting several of them together along the way. (actually most of the last 6 years, the Minstrel 1 was December 2016)
Today it's time for a change, I am going to be putting together someone else's kits.
These are two RC2014 modules, direct from z80kits.com, the home of RC2014.
I'll look at the IO card in another post. First I am looking at a sound card for the RC2014 bus designed by Ed Brindley and now produced by Z80Kits.
This can use the AY-3-8910 or the Yamaha YM2149 sound chips (and with an adapter, the AY-3-8912) . These are three channel programmable sound generators chips, as used on many 1980s computers, such as the ZX Spectrum +2, the Oric, Atari ST etc. They also have one or two 8 bit IO ports, which are used on those machines for joysticks or keyboard or printer interfaces etc.
If I remember correctly, the same silicon is inside both the 40 pin AY-3-8910 and the 28 pin AY-3-8192, and some of the additional IO lines on the 40 pin chip are simply not connected to pins on the 28 pin version. The 40 pin versions seems to be cheaper and easier to get hold of these days. The Yamaha version seems to have some improvements, and apparently many of the AY-3 chips are actually remarked Yamaha chips. (I did order some blatantly remarked / fake AY-3-8910 chips from ebay a few weeks ago, but they remain lost in the postal backlog)
There are two versions of the kit available, I chose one that comes with an additional PCB to allow you to use the 28 pin version. I wasn't planning to use this, but I thought it might come in handy one day......
Construction followed the normal practices for boards like this (other than me grumbling under my breath about having to look up component values on the bill of materials.....)
The only change I made was using turned pin sockets for the ICs. The kit with the adapter so didn't have a 40 pin socket, but I prefer turned pin types anyway. Just my preference (and what I have to hand).
I decided to start with it in the side socket on the Minstrel 4D, it's easier to see and change the jumpers if I needed to. There are an awful lot of jumpers on there, to allow different addresses and clock speeds to be used. (this is a Revision 5 board, there is a Revision 6 with a built in crystal oscillator, but this seems to be the preferred version)
I pressed the power button on the Minstrel 4D and nothing happened.
That's not normal. The power LED didn't even come on.
Then I noticed the power supply was in current limiting. Oops. That's not right.
Ah, that might be the problem. I couldn't have picked a better pair of pins to short if I tried. Looks like 5V and 0V.
To be fair, it is rather cold in the workshop upstairs that I use for soldering and drilling and all the sort of messy stuff I don't want going on in the office below. I was going as fast as I could, and I let that solder bridge slip through.
> USE HAT
> USE COAT
> GO WORKSHOP
> USE SOLDERWICK
OK, that's better, let's try again.
It powered on this time. So let's give it a go.
There is a test program listed on George Beckett's github page: https://github.com/markgbeckett/jupiter_ace/tree/master/rc2014_sound_card
However, there is no associated .tap file, so I will need to type it in. But fear not, this is a Minstrel 4D.
Just wire up an FTDI serial cable and go to a terminal program and paste in the text.
And the program is automagically typed in for you.
Running that program produced some nice scales from the speakers, so it sounds like it is working.
Looking at the output on the scope, there is minimal DC offset, so this is probably a genuine AY-3-8910, where the offset would be around 200mV. The Yamaha chips (and remarked Yamaha chips) will show more like 2V. This will be a good way to identify the chips from ebay, if they turn out to be functional fakes rather then just useless lumps of plastic with somewhere near 40 pins sticking out.
Next test was Valkyr, see a previous post on all the fun that was had getting that running: http://blog.tynemouthsoftware.co.uk/2022/10/valkyr-one-game-so-many-changes.html
The game originally supported the Boldfield Soundbox, which also used the AY-3-8910 chip, but with different address mapping. There is a version on George's github which has been modified to work with this card and includes the other changes to make it run smoothly on a Minstrel 4th or 4D.
On the Minstrel 4D, you can load this by browsing the SD card for the TAP file and selecting option 1, LOAD valkyr valkyr so it will automatically load and run.
Select Soundbox (EME/Boldfield) (Essex Micro Electronics designed the Soundbox for Boldfield as far as I can tell).
When the game starts you are greeted with proper game music and effects, far above what you get with the onboard beeper. Very impressive.
There are more things to test, both on the Minstrel 4D and also on a more traditional RC2014 system, look out for those in future posts. I also have the IO board to build and something exciting to test that with.
The Minstrel 4D kits are shipping now, you can order one from The Future Was 8 bit
More info in a previous post:
The YM2149 Sound Card is available from Z80Kits.com
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