diff --git a/doc/RETRO-Book.md b/doc/RETRO-Book.md
index 27e8c48..134438d 100644
--- a/doc/RETRO-Book.md
+++ b/doc/RETRO-Book.md
@@ -3316,6 +3316,112 @@ The standard system is configured with a very deep data stack
In actual use, your programs are unlikely to ever need this,
but if you do, keep the limits in mind.
+# Multiple Cores
+
+Nga has optional support for multiple virtual cores. These
+are not directly comparable to actual CPU cores, but do
+allow for a degree of multitasking.
+
+Cores share a single address space for RAM, but each gets
+its own data and address stacks, as well as 24 internal
+registers for private data storage. The floating point stack
+is shared across all cores.
+
+Execution is handled in a round-robin fashion. After an
+instruction bundle is processed, Nga will pass control to the
+next active core. Note that this means that execution will
+stall when an I/O operation is running.
+
+## Enabling
+
+To make use of the multicore support, edit the `Makefile` and
+uncomment the lines reading:
+
+ # ENABLED += -DENABLE_MULTICORE
+ # DEVICES += interface/multicore.retro
+
+And rebuild.
+
+## Scheduling
+
+Nga switches to the next active core after execution of an
+instruction bundle completes on the current core.
+
+## Initialization
+
+To initialize a core, pass the core identifier (0 through 7)
+to `core:init`. This will zero out its internal registers and
+set it to.
+
+Example:
+
+ #4 core:init
+
+## Starting a Core
+
+Initialization does not activate a core. To do this, you need
+to use `core:start`. Pass this the address of the word to
+run and the core number.
+
+Example:
+
+ :a [ $a c:put ] forever ;
+ &a #4 core:start
+
+## Pausing a Core
+
+Two words are provided for suspending a core. The first is
+`core:pause`. Pass this the core number to pause.
+
+Example:
+
+ #4 core:pause
+
+The second option is intended if you need the currently
+active core to pause. This word is `core:pause-current`.
+
+Example:
+
+ core:pause-current
+
+## Resuming a Core
+
+To reactive a core, use `core:resume`. This takes the core
+number to activate.
+
+Example:
+
+ #4 core:resume
+
+## Registers
+
+Each core has 24 internal memory spaces. You can read these
+with `core:rr` and modify them with `core:wr`. (These are
+used identically to `fetch` and `store`). Registers are
+numbered as 0 through 23.
+
+A core can not access the registers in another core.
+
+## Napia
+
+The implementation here is based on the multicore model used
+in Napia, the virtual machine being written for the Retro
+on smaller targets. Code written to work with this will be
+usable on Retro/Napia with minimal changes.
+
+The main differences are that under Nga, this is an optional
+extension, but in Napia, it is part of the standard system.
+
+## Other Notes
+
+On startup, execution occurs on core 0, with only core 0 being
+initialized.
+
+I/O is run on the currently active core. Since I/O is blocking,
+waiting for an interaction to occur will prevent other cores
+from running until the operation is complete.
+
+
# Internals: Nga Virtual Machine
## Overview
diff --git a/doc/book/techniques/multicore b/doc/book/techniques/multicore
new file mode 100644
index 0000000..b5246c8
--- /dev/null
+++ b/doc/book/techniques/multicore
@@ -0,0 +1,105 @@
+# Multiple Cores
+
+Nga has optional support for multiple virtual cores. These
+are not directly comparable to actual CPU cores, but do
+allow for a degree of multitasking.
+
+Cores share a single address space for RAM, but each gets
+its own data and address stacks, as well as 24 internal
+registers for private data storage. The floating point stack
+is shared across all cores.
+
+Execution is handled in a round-robin fashion. After an
+instruction bundle is processed, Nga will pass control to the
+next active core. Note that this means that execution will
+stall when an I/O operation is running.
+
+## Enabling
+
+To make use of the multicore support, edit the `Makefile` and
+uncomment the lines reading:
+
+ # ENABLED += -DENABLE_MULTICORE
+ # DEVICES += interface/multicore.retro
+
+And rebuild.
+
+## Scheduling
+
+Nga switches to the next active core after execution of an
+instruction bundle completes on the current core.
+
+## Initialization
+
+To initialize a core, pass the core identifier (0 through 7)
+to `core:init`. This will zero out its internal registers and
+set it to.
+
+Example:
+
+ #4 core:init
+
+## Starting a Core
+
+Initialization does not activate a core. To do this, you need
+to use `core:start`. Pass this the address of the word to
+run and the core number.
+
+Example:
+
+ :a [ $a c:put ] forever ;
+ &a #4 core:start
+
+## Pausing a Core
+
+Two words are provided for suspending a core. The first is
+`core:pause`. Pass this the core number to pause.
+
+Example:
+
+ #4 core:pause
+
+The second option is intended if you need the currently
+active core to pause. This word is `core:pause-current`.
+
+Example:
+
+ core:pause-current
+
+## Resuming a Core
+
+To reactive a core, use `core:resume`. This takes the core
+number to activate.
+
+Example:
+
+ #4 core:resume
+
+## Registers
+
+Each core has 24 internal memory spaces. You can read these
+with `core:rr` and modify them with `core:wr`. (These are
+used identically to `fetch` and `store`). Registers are
+numbered as 0 through 23.
+
+A core can not access the registers in another core.
+
+## Napia
+
+The implementation here is based on the multicore model used
+in Napia, the virtual machine being written for the Retro
+on smaller targets. Code written to work with this will be
+usable on Retro/Napia with minimal changes.
+
+The main differences are that under Nga, this is an optional
+extension, but in Napia, it is part of the standard system.
+
+## Other Notes
+
+On startup, execution occurs on core 0, with only core 0 being
+initialized.
+
+I/O is run on the currently active core. Since I/O is blocking,
+waiting for an interaction to occur will prevent other cores
+from running until the operation is complete.
+
diff --git a/doc/html/chapters/techniques/multicore.html b/doc/html/chapters/techniques/multicore.html
new file mode 100644
index 0000000..7704837
--- /dev/null
+++ b/doc/html/chapters/techniques/multicore.html
@@ -0,0 +1,152 @@
+
+
+
+.
+
+
+Multiple Cores
+
+Nga has optional support for multiple virtual cores. These
+are not directly comparable to actual CPU cores, but do
+allow for a degree of multitasking.
+
+Cores share a single address space for RAM, but each gets
+its own data and address stacks, as well as 24 internal
+registers for private data storage. The floating point stack
+is shared across all cores.
+
+Execution is handled in a round-robin fashion. After an
+instruction bundle is processed, Nga will pass control to the
+next active core. Note that this means that execution will
+stall when an I/O operation is running.
+
+Enabling
+
+To make use of the multicore support, edit the Makefile and
+uncomment the lines reading:
+
+# ENABLED += -DENABLE_MULTICORE
+# DEVICES += interface/multicore.retro
+
+And rebuild.
+
+Scheduling
+
+Nga switches to the next active core after execution of an
+instruction bundle completes on the current core.
+
+Initialization
+
+To initialize a core, pass the core identifier (0 through 7)
+to core:init. This will zero out its internal registers and
+set it to.
+
+Example:
+
+#4 core:init
+
+Starting a Core
+
+Initialization does not activate a core. To do this, you need
+to use core:start. Pass this the address of the word to
+run and the core number.
+
+Example:
+
+:a [ $a c:put ] forever ;
+&a #4 core:start
+
+Pausing a Core
+
+Two words are provided for suspending a core. The first is
+core:pause. Pass this the core number to pause.
+
+Example:
+
+#4 core:pause
+
+The second option is intended if you need the currently
+active core to pause. This word is core:pause-current.
+
+Example:
+
+core:pause-current
+
+Resuming a Core
+
+To reactive a core, use core:resume. This takes the core
+number to activate.
+
+Example:
+
+#4 core:resume
+
+Registers
+
+Each core has 24 internal memory spaces. You can read these
+with core:rr and modify them with core:wr. (These are
+used identically to fetch and store). Registers are
+numbered as 0 through 23.
+
+A core can not access the registers in another core.
+
+Napia
+
+The implementation here is based on the multicore model used
+in Napia, the virtual machine being written for the Retro
+on smaller targets. Code written to work with this will be
+usable on Retro/Napia with minimal changes.
+
+The main differences are that under Nga, this is an optional
+extension, but in Napia, it is part of the standard system.
+
+Other Notes
+
+On startup, execution occurs on core 0, with only core 0 being
+initialized.
+
+I/O is run on the currently active core. Since I/O is blocking,
+waiting for an interaction to occur will prevent other cores
+from running until the operation is complete.
+
+
+
diff --git a/doc/html/index.html b/doc/html/index.html
index 8a4f14b..20decab 100644
--- a/doc/html/index.html
+++ b/doc/html/index.html
@@ -1 +1 @@
-
Retro Forth: Manual
Retro Forth
• Introduction
• Obtaining RETRO
• Building on Unix
• Building on Windows
• Building Alternative Implementations
• Advanced and Custom Builds
• Starting RETRO
• Basic User Interactions
• Literate Source With Unu
• Markdown
• A Quick Tutorial
• Syntax
• Toolchain: Additional Tools
• Toolchain: retro-compiler
• Manpage: retro(1)
• Manpage: retro-describe(1)
• Manpage: retro-document(1)
• Manpage: retro-embedimage(1)
• Manpage: retro-extend(1)
• Manpage: retro-locate(1)
• Manpage: retro-muri(1)
• Manpage: retro-tags(1)
• Naming Conventions
• The Return Stack
• Stack Diagrams
• Arrays
• Assembly
• Buffer
• Characters
• Defining Words
• The Dictionary
• Floating Point
• Working With Files
• Loops
• Numbers
• Pointers
• Quotes
• Sockets
• Scripting
• Strings
• Using Combinators
• Word Classes
• Checking the Version
• Errors
• Lexical Scope
• The Stacks
• The Nga Virtual Machine
• Interface Layers
• Basic I/O
• Detailed I/O
• Image
• Calling Retro From C
• Historical Papers
• Metacompiling
• Self-Hosting
• Sigils
• Kernel Words
• Ngaro to Nga
• RETRO11 Retrospective
• Security
• Underscores in Names
• Code It Yourself Manifesto
• Deprecation Policy
• Copyrights
\ No newline at end of file
+
Retro Forth: Manual
Retro Forth
• Introduction
• Obtaining RETRO
• Building on Unix
• Building on Windows
• Building Alternative Implementations
• Advanced and Custom Builds
• Starting RETRO
• Basic User Interactions
• Literate Source With Unu
• Markdown
• A Quick Tutorial
• Syntax
• Toolchain: Additional Tools
• Toolchain: retro-compiler
• Manpage: retro(1)
• Manpage: retro-describe(1)
• Manpage: retro-document(1)
• Manpage: retro-embedimage(1)
• Manpage: retro-extend(1)
• Manpage: retro-locate(1)
• Manpage: retro-muri(1)
• Manpage: retro-tags(1)
• Naming Conventions
• The Return Stack
• Stack Diagrams
• Arrays
• Assembly
• Buffer
• Characters
• Defining Words
• The Dictionary
• Floating Point
• Working With Files
• Loops
• Numbers
• Pointers
• Quotes
• Sockets
• Scripting
• Strings
• Using Combinators
• Word Classes
• Checking the Version
• Errors
• Lexical Scope
• The Stacks
• Multicore Support
• The Nga Virtual Machine
• Interface Layers
• Basic I/O
• Detailed I/O
• Image
• Calling Retro From C
• Historical Papers
• Metacompiling
• Self-Hosting
• Sigils
• Kernel Words
• Ngaro to Nga
• RETRO11 Retrospective
• Security
• Underscores in Names
• Code It Yourself Manifesto
• Deprecation Policy
• Copyrights
\ No newline at end of file
diff --git a/tools/book-chapters.retro b/tools/book-chapters.retro
index 4bc2b46..95bb2ce 100755
--- a/tools/book-chapters.retro
+++ b/tools/book-chapters.retro
@@ -47,6 +47,7 @@ This contains the list of files for the chapters in the book.
{ 'Errors 'techniques/errors }
{ 'Lexical_Scope 'techniques/lexical-scope }
{ 'The_Stacks 'techniques/the-stacks }
+ { 'Multicore_Support 'techniques/multicore }
{ 'The_Nga_Virtual_Machine 'internals/nga }
{ 'Interface_Layers 'internals/interface-layers }
{ 'Basic_I/O 'internals/io }