Gopher2600 v0.21.0 is released. Gopher2600 is an emulator for the Atari 2600. Whilst the performance is not as efficient as some other emulators it is none-the-less suitable for playing games, on a reasonably modern computer, at the required 60fps. (The development machine for Gopher2600 has been an i3-3225, dating from around 2012.)

Gopher2600 v0.21.0 changelog:
Performance
significant performance increase when built with pgo file. the "release" target in the Makefile does this
18% for regular ROMs
13% for a typical ARM ROM
DPC+ could return formatted errors on calls to Access(). this had a significant performance impact on cartridges that triggered the error
Display
new render pipeline
better scaling
screenshotting method altered
improved input latency
Controllers
support for stelladaptor
joystick and paddle only (driving controller is not yet supported at all)
Debugger
magnification of debugging screen
Setup Database
TV entry type changed. existing setup database entries will need to be altered
Database
entries can be commented out
DWARF / local variables
calculation of call frame address is now correct in more (all?) instances
Bug Fixes
fixed ARM memory read bug that was most likely to be encountered during DWARF parsing/loading
WATCH command would halt on a check of an address, even when other conditions (read/write) were not met
behaviour of STEP BACK in HBLANK area
behaviour of random pins
Note that as of this version, version 1.20 of the Go compiler is required.

Download: Gopher2600 v0.21.0
Source:Here