diff --git a/apps/debugger/src/app/debugger-api.ts b/apps/debugger/src/app/debugger-api.ts
index 0f99518e78..e1b66a3d48 100644
--- a/apps/debugger/src/app/debugger-api.ts
+++ b/apps/debugger/src/app/debugger-api.ts
@@ -111,7 +111,8 @@ export const DebuggerApiMixin = (Base) => class extends Base {
         }
         return null
       },
-      debugWithGeneratedSources: false
+      debugWithGeneratedSources: false,
+      fork: 'berlin'
     })
     return await debug.debugger.traceManager.getTrace(hash)
   }
diff --git a/apps/remix-ide/src/app/tabs/runTab/settings.js b/apps/remix-ide/src/app/tabs/runTab/settings.js
index dd726c09be..21085d9e27 100644
--- a/apps/remix-ide/src/app/tabs/runTab/settings.js
+++ b/apps/remix-ide/src/app/tabs/runTab/settings.js
@@ -98,9 +98,17 @@ class SettingsUI {
         </label>
         <div class="${css.environment}">
           <select id="selectExEnvOptions" data-id="settingsSelectEnvOptions" class="form-control ${css.select} custom-select">
-            <option id="vm-mode"
+            <option id="vm-mode-berlin"
               title="Execution environment does not connect to any node, everything is local and in memory only."
-              value="vm" name="executionContext"> JavaScript VM
+              value="vm-berlin" name="executionContext" fork="berlin" > JavaScript VM (Berlin)
+            </option>
+            <option id="vm-mode-muirglacier"
+              title="Execution environment does not connect to any node, everything is local and in memory only."
+              value="vm-istanbul" name="executionContext" fork="istanbul"> JavaScript VM (Istanbul)
+            </option>
+            <option id="vm-mode-london"
+              title="Execution environment does not connect to any node, everything is local and in memory only."
+              value="vm-london" name="executionContext" fork="london"> JavaScript VM (London)
             </option>
             <option id="injected-mode"
               title="Execution environment has been provided by Metamask or similar provider."
@@ -236,11 +244,14 @@ class SettingsUI {
     this.blockchain.event.register('removeProvider', name => removeProvider(name))
 
     selectExEnv.addEventListener('change', (event) => {
-      const context = selectExEnv.options[selectExEnv.selectedIndex].value
-      this.setExecutionContext(context)
+      const provider = selectExEnv.options[selectExEnv.selectedIndex]
+      const fork = provider.getAttribute('fork')
+      let context = provider.value
+      context = context.startsWith('vm') ? 'vm' : context
+      this.setExecutionContext({ context, fork })
     })
 
-    selectExEnv.value = this.blockchain.getProvider()
+    selectExEnv.value = this._getProviderDropdownValue()
   }
 
   setExecutionContext (context) {
@@ -278,9 +289,15 @@ class SettingsUI {
     `
   }
 
+  _getProviderDropdownValue () {
+    const provider = this.blockchain.getProvider()
+    const fork = this.blockchain.getFork()
+    return provider === 'vm' ? provider + '-' + fork : provider
+  }
+
   setFinalContext () {
     // set the final context. Cause it is possible that this is not the one we've originaly selected
-    this.selectExEnv.value = this.blockchain.getProvider()
+    this.selectExEnv.value = this._getProviderDropdownValue()
     this.event.trigger('clearInstance', [])
     this.updatePlusButton()
   }
diff --git a/apps/remix-ide/src/blockchain/blockchain.js b/apps/remix-ide/src/blockchain/blockchain.js
index e5e682fa95..a6e03d26d9 100644
--- a/apps/remix-ide/src/blockchain/blockchain.js
+++ b/apps/remix-ide/src/blockchain/blockchain.js
@@ -208,6 +208,10 @@ class Blockchain {
     return this.executionContext.getProvider()
   }
 
+  getFork () {
+    return this.executionContext.getCurrentFork()
+  }
+
   isWeb3Provider () {
     const isVM = this.getProvider() === 'vm'
     const isInjected = this.getProvider() === 'injected'
diff --git a/apps/remix-ide/src/blockchain/execution-context.js b/apps/remix-ide/src/blockchain/execution-context.js
index dbefacda87..6e5791ca23 100644
--- a/apps/remix-ide/src/blockchain/execution-context.js
+++ b/apps/remix-ide/src/blockchain/execution-context.js
@@ -21,7 +21,8 @@ export class ExecutionContext {
     this.executionContext = null
     this.blockGasLimitDefault = 4300000
     this.blockGasLimit = this.blockGasLimitDefault
-    this.currentFork = 'berlin'
+    this.defaultFork = 'berlin'
+    this.currentFork = this.defaultFork
     this.mainNetGenesisHash = '0xd4e56740f876aef8c010b86a40d5f56745a118d0906a34e69aec8c0db1cb8fa3'
     this.customNetWorks = {}
     this.blocks = {}
@@ -48,6 +49,10 @@ export class ExecutionContext {
     return this.executionContext
   }
 
+  getCurrentFork () {
+    return this.currentFork
+  }
+
   isVM () {
     return this.executionContext === 'vm'
   }
@@ -58,7 +63,7 @@ export class ExecutionContext {
 
   web3 () {
     if (this.customWeb3[this.executionContext]) return this.customWeb3[this.executionContext]
-    return this.isVM() ? this.vms[this.currentFork].web3vm : web3
+    return web3
   }
 
   detectNetwork (callback) {
@@ -118,16 +123,21 @@ export class ExecutionContext {
     this.executionContextChange(context, endPointUrl, confirmCb, infoCb, null)
   }
 
-  executionContextChange (context, endPointUrl, confirmCb, infoCb, cb) {
+  executionContextChange (value, endPointUrl, confirmCb, infoCb, cb) {
+    const context = value.context
+    const fork = value.fork || this.defaultFork
     if (!cb) cb = () => {}
     if (!confirmCb) confirmCb = () => {}
     if (!infoCb) infoCb = () => {}
     if (context === 'vm') {
       this.executionContext = context
+      this.currentFork = fork
       this.event.trigger('contextChanged', ['vm'])
       return cb()
     }
 
+    this.currentFork = this.defaultFork
+
     if (context === 'injected') {
       if (injectedProvider === undefined) {
         infoCb('No injected Web3 provider found. Make sure your provider (e.g. MetaMask) is active and running (when recently activated you may have to reload the page).')
@@ -147,7 +157,7 @@ export class ExecutionContext {
     }
     if (this.customNetWorks[context]) {
       var network = this.customNetWorks[context]
-      this.setProviderFromEndpoint(network.provider, network.name, (error) => {
+      this.setProviderFromEndpoint(network.provider, { context: network.name }, (error) => {
         if (error) infoCb(error)
         cb()
       })
@@ -184,8 +194,9 @@ export class ExecutionContext {
 
   // TODO: remove this when this function is moved
 
-  setProviderFromEndpoint (endpoint, context, cb) {
+  setProviderFromEndpoint (endpoint, value, cb) {
     const oldProvider = web3.currentProvider
+    const context = value.context
 
     web3.setProvider(endpoint)
     web3.eth.net.isListening((err, isConnected) => {
diff --git a/apps/remix-ide/src/blockchain/providers/vm.js b/apps/remix-ide/src/blockchain/providers/vm.js
index e01b7b08d2..0bc9b85d3d 100644
--- a/apps/remix-ide/src/blockchain/providers/vm.js
+++ b/apps/remix-ide/src/blockchain/providers/vm.js
@@ -5,12 +5,6 @@ const { Provider, extend } = require('@remix-project/remix-simulator')
 class VMProvider {
   constructor (executionContext) {
     this.executionContext = executionContext
-    this.RemixSimulatorProvider = new Provider({})
-    this.RemixSimulatorProvider.init()
-    this.web3 = new Web3(this.RemixSimulatorProvider)
-    extend(this.web3)
-    this.accounts = {}
-    this.executionContext.setWeb3('vm', this.web3)
   }
 
   getAccounts (cb) {
@@ -23,8 +17,14 @@ class VMProvider {
   }
 
   resetEnvironment () {
+    this.accounts = {}
+    this.RemixSimulatorProvider = new Provider({ fork: this.executionContext.getCurrentFork() })
+    this.RemixSimulatorProvider.init()
     this.RemixSimulatorProvider.Accounts.resetAccounts()
+    this.web3 = new Web3(this.RemixSimulatorProvider)
+    extend(this.web3)
     this.accounts = {}
+    this.executionContext.setWeb3('vm', this.web3)
   }
 
   // TODO: is still here because of the plugin API
diff --git a/libs/remix-debug/src/Ethdebugger.ts b/libs/remix-debug/src/Ethdebugger.ts
index 3c492e1812..4c023c6028 100644
--- a/libs/remix-debug/src/Ethdebugger.ts
+++ b/libs/remix-debug/src/Ethdebugger.ts
@@ -41,7 +41,7 @@ export class Ethdebugger {
     this.opts = opts
 
     this.event = new EventManager()
-    this.traceManager = new TraceManager({ web3: this.web3 })
+    this.traceManager = new TraceManager({ web3: this.web3, fork: this.opts.fork })
     this.codeManager = new CodeManager(this.traceManager)
     this.solidityProxy = new SolidityProxy({ getCurrentCalledAddressAt: this.traceManager.getCurrentCalledAddressAt.bind(this.traceManager), getCode: this.codeManager.getCode.bind(this.codeManager) })
     this.storageResolver = null
@@ -55,7 +55,7 @@ export class Ethdebugger {
   }
 
   setManagers () {
-    this.traceManager = new TraceManager({ web3: this.web3 })
+    this.traceManager = new TraceManager({ web3: this.web3, fork: this.opts.fork })
     this.codeManager = new CodeManager(this.traceManager)
     this.solidityProxy = new SolidityProxy({ getCurrentCalledAddressAt: this.traceManager.getCurrentCalledAddressAt.bind(this.traceManager), getCode: this.codeManager.getCode.bind(this.codeManager) })
     this.storageResolver = null
diff --git a/libs/remix-debug/src/code/codeManager.ts b/libs/remix-debug/src/code/codeManager.ts
index e7e46f4740..e3b89873b7 100644
--- a/libs/remix-debug/src/code/codeManager.ts
+++ b/libs/remix-debug/src/code/codeManager.ts
@@ -4,6 +4,7 @@ import { EventManager } from '../eventManager'
 import { isContractCreation } from '../trace/traceHelper'
 import { findNodeAtInstructionIndex } from '../source/sourceMappingDecoder'
 import { CodeResolver } from './codeResolver'
+import { TraceManager } from '../trace/traceManager' // eslint-disable-line
 
 /*
   resolve contract code referenced by vmtrace in order to be used by asm listview.
@@ -15,7 +16,7 @@ import { CodeResolver } from './codeResolver'
 export class CodeManager {
   event
   isLoading: boolean
-  traceManager
+  traceManager: TraceManager
   codeResolver
 
   constructor (_traceManager) {
@@ -32,7 +33,8 @@ export class CodeManager {
             return resolve(code)
           })
         })
-      }
+      },
+      fork: this.traceManager.getFork()
     })
   }
 
diff --git a/libs/remix-debug/src/code/codeResolver.ts b/libs/remix-debug/src/code/codeResolver.ts
index 308b9c5293..94be135a5c 100644
--- a/libs/remix-debug/src/code/codeResolver.ts
+++ b/libs/remix-debug/src/code/codeResolver.ts
@@ -6,12 +6,14 @@ export class CodeResolver {
   bytecodeByAddress
   instructionsByAddress
   instructionsIndexByBytesOffset
+  fork
 
-  constructor ({ getCode }) {
+  constructor ({ getCode, fork }) {
     this.getCode = getCode
     this.bytecodeByAddress = {} // bytes code by contract addesses
     this.instructionsByAddress = {} // assembly items instructions list by contract addesses
     this.instructionsIndexByBytesOffset = {} // mapping between bytes offset and instructions index.
+    this.fork = fork
   }
 
   clear () {
@@ -39,7 +41,7 @@ export class CodeResolver {
   }
 
   formatCode (hexCode) {
-    const [code, instructionsIndexByBytesOffset] = nameOpCodes(Buffer.from(hexCode.substring(2), 'hex'))
+    const [code, instructionsIndexByBytesOffset] = nameOpCodes(Buffer.from(hexCode.substring(2), 'hex'), this.fork)
     return { code, instructionsIndexByBytesOffset }
   }
 
diff --git a/libs/remix-debug/src/code/codeUtils.ts b/libs/remix-debug/src/code/codeUtils.ts
index 1c0c88374a..061b64e8c8 100644
--- a/libs/remix-debug/src/code/codeUtils.ts
+++ b/libs/remix-debug/src/code/codeUtils.ts
@@ -1,14 +1,23 @@
 'use strict'
-import opcodes from './opcodes'
+import Common from '@ethereumjs/common'
+import { getOpcodesForHF } from '@ethereumjs/vm/dist/evm/opcodes'
+
+export function nameOpCodes (raw, hardfork) {
+  const common = new Common({ chain: 'mainnet', hardfork })
+  const opcodes = getOpcodesForHF(common)
 
-export function nameOpCodes (raw) {
   let pushData = ''
   const codeMap = {}
   const code = []
 
   for (let i = 0; i < raw.length; i++) {
     const pc = i
-    const curOpCode = opcodes(raw[pc], false).name
+    let curOpCode
+    try {
+      curOpCode = opcodes.get(raw[pc]).fullName
+    } catch (e) {
+      curOpCode = 'INVALID'
+    }
     codeMap[i] = code.length
     // no destinations into the middle of PUSH
     if (curOpCode.slice(0, 4) === 'PUSH') {
@@ -30,9 +39,17 @@ export function nameOpCodes (raw) {
  * information about the opcode.
  */
 export function parseCode (raw) {
+  const common = new Common({ chain: 'mainnet', hardfork: 'berlin' })
+  const opcodes = getOpcodesForHF(common)
+
   const code = []
   for (let i = 0; i < raw.length; i++) {
-    const opcode = opcodes(raw[i], true)
+    let opcode
+    try {
+      opcode = opcodes.get(raw[i]).fullName
+    } catch (e) {
+      opcode = 'INVALID'
+    }
     if (opcode.name.slice(0, 4) === 'PUSH') {
       const length = raw[i] - 0x5f
       opcode['pushData'] = raw.slice(i + 1, i + length + 1)
@@ -60,5 +77,5 @@ export function log (num, base) {
 }
 
 export function roundLog (num, base) {
-  return Math.ceil(this.log(num, base))
+  return Math.ceil(log(num, base))
 }
diff --git a/libs/remix-debug/src/debugger/debugger.ts b/libs/remix-debug/src/debugger/debugger.ts
index 11395026b3..76d28746bd 100644
--- a/libs/remix-debug/src/debugger/debugger.ts
+++ b/libs/remix-debug/src/debugger/debugger.ts
@@ -26,7 +26,8 @@ export class Debugger {
     this.debugger = new Ethdebugger({
       web3: options.web3,
       debugWithGeneratedSources: options.debugWithGeneratedSources,
-      compilationResult: this.compilationResult
+      compilationResult: this.compilationResult,
+      fork: options.fork
     })
 
     const { traceManager, callTree, solidityProxy } = this.debugger
diff --git a/libs/remix-debug/src/trace/traceManager.ts b/libs/remix-debug/src/trace/traceManager.ts
index c5fbbc3c3f..a42beed101 100644
--- a/libs/remix-debug/src/trace/traceManager.ts
+++ b/libs/remix-debug/src/trace/traceManager.ts
@@ -7,6 +7,7 @@ import { util } from '@remix-project/remix-lib'
 
 export class TraceManager {
   web3
+  fork: string
   isLoading: boolean
   trace
   traceCache
@@ -16,6 +17,7 @@ export class TraceManager {
 
   constructor (options) {
     this.web3 = options.web3
+    this.fork = options.fork
     this.isLoading = false
     this.trace = null
     this.traceCache = new TraceCache()
@@ -70,6 +72,10 @@ export class TraceManager {
     this.traceCache.init()
   }
 
+  getFork () {
+    return this.fork
+  }
+
   // API section
   inRange (step) {
     return this.isLoaded() && step >= 0 && step < this.trace.length
diff --git a/libs/remix-simulator/src/provider.ts b/libs/remix-simulator/src/provider.ts
index 276b66ca15..152976227a 100644
--- a/libs/remix-simulator/src/provider.ts
+++ b/libs/remix-simulator/src/provider.ts
@@ -18,14 +18,12 @@ export class Provider {
   Accounts
   Transactions
   methods
-  host: string
   connected: boolean;
 
-  constructor (host: string = 'vm', options: Record<string, unknown> = {}) {
+  constructor (options: Record<string, unknown> = {}) {
     this.options = options
-    this.host = host
     this.connected = true
-    this.vmContext = new VMContext()
+    this.vmContext = new VMContext(options['fork'])
 
     this.Accounts = new Accounts(this.vmContext)
     this.Transactions = new Transactions(this.vmContext)
diff --git a/libs/remix-simulator/src/vm-context.ts b/libs/remix-simulator/src/vm-context.ts
index a6406b2391..e0a3aef849 100644
--- a/libs/remix-simulator/src/vm-context.ts
+++ b/libs/remix-simulator/src/vm-context.ts
@@ -91,24 +91,18 @@ export class VMContext {
   blocks
   latestBlockNumber
   txs
-  vms
+  defaultFork
+  currentVm
   web3vm
   logsManager
   exeResults
 
-  constructor () {
+  constructor (fork?) {
     this.blockGasLimitDefault = 4300000
     this.blockGasLimit = this.blockGasLimitDefault
-    this.currentFork = 'berlin'
-    this.vms = {
-      /*
-      byzantium: createVm('byzantium'),
-      constantinople: createVm('constantinople'),
-      petersburg: createVm('petersburg'),
-      istanbul: createVm('istanbul'),
-      */
-      berlin: this.createVm('berlin')
-    }
+    this.defaultFork = fork || 'berlin'
+    this.currentFork = this.defaultFork
+    this.currentVm = this.createVm(this.currentFork)
     this.blocks = {}
     this.latestBlockNumber = 0
     this.txs = {}
@@ -122,7 +116,7 @@ export class VMContext {
     const vm = new VM({
       common,
       activatePrecompiles: true,
-      stateManager: stateManager,
+      stateManager,
       allowUnlimitedContractSize: true
     })
 
@@ -131,8 +125,12 @@ export class VMContext {
     return { vm, web3vm, stateManager, common }
   }
 
+  getCurrentFork () {
+    return this.currentFork
+  }
+
   web3 () {
-    return this.vms[this.currentFork].web3vm
+    return this.currentVm.web3vm
   }
 
   blankWeb3 () {
@@ -140,11 +138,11 @@ export class VMContext {
   }
 
   vm () {
-    return this.vms[this.currentFork].vm
+    return this.currentVm.vm
   }
 
   vmObject () {
-    return this.vms[this.currentFork]
+    return this.currentVm
   }
 
   addBlock (block) {