[FWD] Fw: MIDI interface. Article from the newspaper "Paragraph" number 18.

At the request of the publisher of the newspaper "Paragraph" Alex Xor: === Cut === Article from the newspaper "Paragraph" #18. MIDI interface. Continuation. Greetings, spektrumists! Once again I propose my project 'MIDI interface for ZX-Spectrum-compatible computers'. Why 'once again'? Because already repeatedly suggested. Unfortunately - to no avail. And that reaction to mine the proposal that was 90% not has the right to be called a result. But I I still don’t lose hope and hope that that there are still enthusiasts with heads left, able to think creatively and work hands that are 'sharpened just right'. Wake up and start helping. Help not me, but, first of all, yourself and the platform that you still do not no matter what, love. This time I I decided to write an article in more detail and I'll try not to miss myself in it important. Where to start? It probably would be worth it start with something that immediately caused would be interesting and attract attention Spectrum users. What can it do? be? Probably some kind of thing that I still haven't had a Spectrum, but which it would not be superfluous to have, and, most importantly, which would be useful for users this computer. As far as I remember the story of Specky, in 1985 year it was refined previous version - memory increased to 128 kilobytes, the number has increased screens and... music was addedprocessor AY-3-8912 (AY-3-8910, YM2149F... - hereinafter - 'AY'). Those. even then the developers were puzzled by the increase Specky's sound capabilities. some time is really this simple the three-voice synthesizer was a godsend for spektrumists, especially for musicians. were written for him music editors, they immediately became use in games and just for dubbing programs. Listening to music written for AY, I was sometimes surprised, with what virtuosity those who wrote this music, used more than modest (according to current times) AY capabilities. And more than once the thought came to them - that they created if they were given more advanced technical means?! Progress does not stand still. Now the possibilities of little AY really can be considered more than modest. And that's it it would be okay if Specky were present time has already 'died'. But! It's painfully tenacious machine. Still exists (from the heart I hope) many of her admirers. But time goes by and since Specky lives, he must improve. And he is being improved - a mouse is connected to it, CD-ROM, hard drive, modem developed... The sound also remained unchanged. One of the most famous developments in this area, in my opinion, is General Sound (GS). Of course, the appearance of this module gives Specky new sound possibilities, for example, you can write music using real instruments, loading them into the module memory.All this is good. Of course, developers worked conscientiously (develop and debugging such a device is very not easy - I know from my own experience), but I immediately noticed that it was too tall complexity of the circuit, it could be greatly simplify. Also, in my opinion look, the choice of the central one is extremely unfortunate processor, which also runs on to the limit of one's capabilities - at the borderline frequency It seems to me that it would have been smarter would be used in this circuit single-chip computers i8031, i8051 or their domestic analogues (BE31, BE51) - while time they were already available and were hardly worth it Is it bigger than the Z80? I think that 8051 with its powerful assembler, high productivity, ability address 64kb RAM + 64kb ROM and ability to easily operate at frequencies up to 25 megahertz would be more appropriate. However, not I will go deeper into the analysis of this scheme, because... this is not the purpose of my article. So, I decided to make my own 'sound card'. There were two options: 1. Develop something similar to GS. 2. Use industrial sound fee. I immediately discarded the first option - game not worth the candle. All the same, with using the available element base (for example, K572PA1) of decent quality sound is impossible to achieve. Yes and fuss a bit much. The second option suited me better. But again, too many problems occurred when trying to connect audioindustrial production boards. And that's it not even in the number of wires and additional microcircuits. The problem is that sound cards exist There are many varieties and each has its own features starting from initialization ports and beyond. In this case, the way out of the situation could be be the use of a family of cards that would have the same connection method and the same communication protocol for reduction. Soon there was such an option found. In my opinion, the smartest thing was would use so-called 'children' MIDI cards'. In order to make it sound like this map you need to do the following: 1. Apply supply voltage to it (+5 V, +12 V, -12 V); 2. Generate a 'reset' signal; 3. Connect to left and right outputs amplifier channels; 4. Transmit via serial channel card management data. There were no problems with points 1-3 - there were a printed circuit board was made on which were set: 'comb' for connection of the card itself, RC chain for signal generation 'reset'