Editing Use the PSG (section)

== The PSG is inside the FPGA of the F256Jr, F256K, F256Jr2 and F256K2 ==

The F256 machines have a dual PSG based on the SN76489 inside the Beatrix FPGA which generate 3 tones of square wave
and one noise generator each.<br>

{| class="wikitable"
|+
!Register Name
!Address
!Description
|-
|PSG_LEFT
|0xD600 
|Send all formatted commands here to the left PSG
|-
|PSG_RIGHT
|0xD610 
|Send all formatted commands here to the right PSG
|-
|PSG_COMBINED_LEFT_RIGHT
|0xD608 
|Send all formatted commands here to both PSG
|-
|SYS1
|0xD6A1 
|System Ctrl reg: bit2 sets PSG_ST = psg status. if 0, left and right are mixed to monaural output. if 1, left and right are normal stereo 
|}

=== Command Formats ===

Example:
<p>To produce a 440 Hz A on Tone 1, send these bytes to address 0xD600 (left PSG)

<p>0b1001 0100 (middle volume "attenuation" command)<br>
0b1000 1101 (low byte of the note)<br>
0b0000 1111 (high byte of the note).

<p>to stop the sound, send to 0xD600:

<p>0b1001 1111 (max attenuation closes off the sound)

=== Frequency bytes in C, meant for tone 1 ===
The high nybble of the low byte is set at 8 for tone 1, 
replace with A for tone 2, or with C for tone 3

uint8_t psgLow[] = {

0x86,
0x8d,0x87,0x84,0x84,0x87,0x8d,0x84,0x8e,0x8b,0x89,0x89,

0x8b,
0x8e,0x83,0x8a,0x82,0x8b,0x86,0x82,0x8f,0x8d,0x8c,0x8c,

0x8d,
0x8f,0x81,0x85,0x89,0x8d,0x83,0x89,0x8f,0x86,0x8e,0x86,

0x8e,
0x87,0x80,0x8a,0x84,0x8e,0x89,0x84,0x8f,0x8b,0x87,0x83,

0x8f,
0x8b,0x88,0x85,0x82,0x8f,0x8c,0x8a,0x87,0x85,0x83,0x81,

0x8f,
0x8d,0x8c,0x8a};


uint8_t psgHigh[] = {

0x3f,
0x3b,0x38,0x35,0x32,0x2f,0x2c,0x2a,0x27,0x25,0x23,0x21,

0x1f,
0x1d,0x1c,0x1a,0x19,0x17,0x16,0x15,0x13,0x12,0x11,0x10,

0xf,
0xe,0xe,0xd,0xc,0xb,0xb,0xa,0x9,0x9,0x8,0x8,

0x7,
0x7,0x7,0x6,0x6,0x5,0x5,0x5,0x4,0x4,0x4,0x4,

0x3,
0x3,0x3,0x3,0x3,0x2,0x2,0x2,0x2,0x2,0x2,0x2,

0x1,
0x1,0x1,0x1};