Changes
Changed the code for Playcity detection. It's now faster and shorter
[[File:PlayCity.jpg|thumb|320px|]]
==Introduction==
* 6 audio channels sound with programmable frequency (stereo line out and speaker mono mix in).
* 4 counter/timer channels for programmable interrupt (including NMI).
Used by the standard BIOS functions
'''MC_BOOT_PROGRAM''' and '''MC_START_PROGRAM''' (vectors $BD13 and $BD16), in particular a peripheral that generates interrupts. Also used by [[FutureOS]].
The PlayCity board use this feature to be sure that the CTC and YMZs circuits are properly reseted reset before using them.
== Light Pen/Gun connector ==
For making it easier to adapt Light Pens/Guns from other systems or new ones, we added a 4 pins connector to the board. The connections are labeled in the board as VCC (+5V), TR (Trigger or D7), LS (Light Sensor) and GND.
Making the system compatible with [[Amstrad_Magnum_Phaser|Amstrad Magnum Phaser]] games, the most accuracy light gun system for CPC.
==Counter/Timer Circuit==
===InformationsInformation===
The Z84C30 has four independently programmable counter/timer channels interfaced directly with the Z80 CPU. You can get full information in the CTC datasheet ([[File:Z80ctc.pdf]]).
Used as a counter, it's synchronized with the CRTC CURSOR signal, generating a smooth high priority rasters interrupt. Used as a
timer (prescaler set to 256), it's its 15.625 kHz signal is scanline-synchronized. That means the time constant is the number of
scanlines to wait before to send an NMI.
====Channel 2/3 ($F882/$F883)====
The channels 2 and 3 are dedicated to general purpose usages. Yes, it's for you! The input for the trigger (TRG2) is the 4 MHz
system clock. The output (ZC/TO0TO2) is linked to the trigger for the channel 3 (TRG3). They can be used as 2x 8-bit or 1x 16-bitcounter/timer. They generate normal interrupts and allow to use using the Z80 vector interrupt (mode 2) too.
===Coding examples===
Each channel is programmed with two bytes; a third is necessary when interrupts are enabled. Once started, the CTC countdown
Don't forget to use RETN for NMI handlers as well as RETI for normal interrupt handlers. In other case, the Z80 CPU will not
aknowledge the next interrupt properly.
==Audio Channels==
===Informations===
the frequency by reprograming the CTC Channel 0.
===YMZ294 Registers===
They are exactly the same than the [[PSG]], only remember there is not PSG I/O registers ($0E-$0F90F) in the YMZ.The registers are write only.
===Coding Examples===
====YMZ Initialization====
{| class="wikitable"
|-
|-
| 1 || $$01 || 2,00 || 1,00 || = CPC
|-
| $2 || || 23,67 00 || 1,33 50 ||
|-
| $3 ||$02 || 3,00 33 || 1,50 67 ||
|-
| $4 || || 3,20 50 || 1,60 75 ||= ZX
|-
| $5 || $03 || 3,33 60 || 1,67 80 ||~ MSX
|-
| $6 || || 3,43 67 || 1,71 83 ||
|-
| $7 || $04 || 3,50 71 || 1,75 86 || ZX
|-
| $8 || || 3,56 75 || 1,78 88 || MSX
|-
| $9 || $05 || 3,60 78 || 1,80 89 ||
|-
| 10 || $A || 3,64 80 || 1,82 90 ||
|-
|-
| 12 || $C || 3,69 83 || 1,85 92 ||
|-
|-
| 14 || $E || 3,73 86 || 1,87 93 ||
|-
|-
| 16 || $0 || 3,76 98 || 1,88 99 ||~ ST
|-
|}
==PlayCity coding tips==Interesting tips or "magic tricks" using the board should be documented here. If the code is long, you must put in other wiki page and link it here.===PlayCity detection===We are going to use the NMI interrupt generator to check if our program is running in a CPC with a PlayCity board.<pre>;=========================; PlayCity check; If it'''Informations''': The rows without s present, A=1; Otherwise, A=0;-------------------------;;=========================macro PlaycityDetection ; Code for NMI management ld a ,#3c ; inc a ld (#66),a ld hl,#45ed ; (inverted) opcodes for retn ld (#67),hl ; If a Playcity is present, the code generates a NMI then stops the counter. ld bc,#F881 ; 3 NOPs CTC Val aree not testedchannel 1 ld hl,%00010111*256 + 2 ; 3 NOPs A NMI every 8 NOPs out (c),h ; 4 NOPs out (c),l ; 4 NOPs ld a,0 ; 2 NOPs A is set to 0. It may If a CTC is present, it will be needed to configure INCed by the INTerruption code inc hl ; 2 NOPs L=3 => Stop CTC channel 0 with "falling edge" instead of"rising edges". nop ; 1 NOPs out (c),l ; 4 NOPs <- If a Playcity is plugged, a NMI should be raised during this opcodemend</pre>
==Downloads==
In [[File:playcity_examples.zip]], you will find more examples with full sources of using the CTC, a customized arkos player that let you play songs using an external YMZ and the ReSeT party demo disk that includes a CPC version of the PT3 Turbo Sound player (6 channels song format).
Another example, in [[File:test_sfx.zip]] you will find a 3 channels SFX player, you can choose the sound chip to be used by the player.
== Software Supporting PlayCity ==
*[[Software_Supporting_PlayCity|List of software supporting the board.]]
[[Category:FutureOS]]
[[Category:Music and sound]]
[[Category:Peripherals]]
Website: [http://centpourcent.net centpourcent.net]
