Added OPL3 supportsound-opl3

1 files changed, 19 insertions, 1 deletions

diff --git a/README.md b/README.md
index f555daf..6380519 100644
--- a/README.md
+++ b/README.md
@@ -10,7 +10,7 @@ TR8 is an 8-bit fantasy console inspired by MIPS, Z80 and 6502 real world CPUs.
 Display:  128 x 128 pixels 16 colors
 Memory:   64K
 CPU:      TR-8, 4M VM instr/sec
-Sound:    TBD
+Sound:    OPL3
 ```
 
 Other features:
@@ -65,6 +65,10 @@ You can then compile and run the example with `make example`.
 | --- | --- | --- |
 | 0xb0 | write | Blitter control |
 | 0xb1 | write | Blitter settings |
+| 0xc0 | write | Sound register selector (primary) |
+| 0xc1 | write | Sound data (primary) |
+| 0xc2 | write | Sound register selector (secondary)|
+| 0xc3 | write | Sound data (secondary) |
 | 0xf0 | read | Status of the controller 1 |
 | 0xf1 | read | Status of the controller 2 |
 
@@ -169,6 +173,20 @@ Current palette (not final) is the default EGA 16 color palette:
 | 14 | `0xffff55` |
 | 15 | `0xffffff` |
 
+### Sound: OPL3
+
+TR8 includes an OPL3 emulator that can be conttolled using ports `0xc0` to
+select register and `0xc1` to write data in the primary set of registers
+(channels 0 to 8), and `0xc2` to select register and `0xc3` to write data in
+the secondary set of registers (channels 9 to 17).
+
+There are a few good resources online on how to program this chip:
+
+* [Programming the AdLib/Sound Blaster FM Music Chips](http://www.shipbrook.net/jeff/sb.html)
+* [Programmer's Guide to Yamaha YMF 262/OPL3 FM Music Synthesizer](https://www.fit.vutbr.cz/~arnost/opl/opl3.html)
+
+Also look at the example code in this repo for some simple sound drivers.
+
 ### Frame interrupt
 
 When interrupts are enabled (IF not set), 60 times per second there will be a