Shift some material cut from running.md to implementation/README.md

1 files changed, 4 insertions, 0 deletions

diff --git a/implementation/README.md b/implementation/README.md
index 3addce09..7f29f70e 100644
--- a/implementation/README.md
+++ b/implementation/README.md
@@ -7,6 +7,10 @@ Notes about how BQN is implemented. There's not too much here yet.
 - [Comparison to Co-dfns](codfns.md) discusses the general compilation strategy and how it compares to the only other array-based compiler.
 - [The BQN virtual machine and runtime](vm.md) describes the non-self-hosted parts of the BQN implementation, that is, everything you need to port it to a new platform.
 
+This repository's BQN implementation is written mainly in BQN: the bytecode [compiler](../src/c.bqn) is completely self-hosted, and the [majority of the runtime](../src/r.bqn) is written in BQN except that it is allowed to define primitives; some preprocessing turns the primitives into identifiers. The remaining part, a VM, can be implemented in any language to obtain a version of BQN running in that language.
+
+The VM used for the online REPL is the [Javascript implementation](../docs/bqn.js). The bytecode matches dzaima/BQN's format, and [an extension](../dc.bqn) to the compiler adjusts the slightly different block declarations to target dzaima+reference BQN. [An earlier experiment](../wc.bqn) targetting [WebAssembly](https://en.wikipedia.org/wiki/WebAssembly) works only on a very small subset of BQN. All versions have automated tests in the [test](../test/) directory.
+
 I have also held some forum discussions on the actual workings of the compiler, but aborted these because the interactive format wasn't doing too much. I haven't yet started on non-interactive replacements.
 
 - [Parenthesis nesting level](https://chat.stackexchange.com/rooms/52405/conversation/lesson-s1-parenthesis-nesting-level)