param(
    [Parameter(Mandatory = $true)]
    [int]$ProcessId,
    [Parameter(Mandatory = $true)]
    [uint64]$Address,
    [int]$Length = 64
)

$source = @'
using System;
using System.ComponentModel;
using System.Runtime.InteropServices;

public static class ProcessMemoryReader
{
    [DllImport("kernel32.dll", SetLastError = true)]
    private static extern IntPtr OpenProcess(uint access, bool inherit, int processId);
    [DllImport("kernel32.dll", SetLastError = true)]
    private static extern bool CloseHandle(IntPtr handle);
    [DllImport("kernel32.dll", SetLastError = true)]
    private static extern bool ReadProcessMemory(IntPtr process, IntPtr address, byte[] buffer,
                                                  UIntPtr size, out UIntPtr bytesRead);

    public static byte[] Read(int processId, ulong address, int length)
    {
        IntPtr process = OpenProcess(0x0010 | 0x0400, false, processId);
        if (process == IntPtr.Zero)
            throw new Win32Exception(Marshal.GetLastWin32Error(), "OpenProcess failed");
        try
        {
            byte[] bytes = new byte[length];
            UIntPtr read;
            if (!ReadProcessMemory(process, new IntPtr(unchecked((long)address)), bytes,
                                   new UIntPtr((uint)length), out read) ||
                read.ToUInt64() != (ulong)length)
                throw new Win32Exception(Marshal.GetLastWin32Error(), "ReadProcessMemory failed");
            return bytes;
        }
        finally
        {
            CloseHandle(process);
        }
    }
}
'@

Add-Type -TypeDefinition $source -Language CSharp
$bytes = [ProcessMemoryReader]::Read($ProcessId, $Address, $Length)
for ($offset = 0; $offset -lt $bytes.Length; $offset += 16) {
    $count = [Math]::Min(16, $bytes.Length - $offset)
    $hex = ($bytes[$offset..($offset + $count - 1)] | ForEach-Object { '{0:x2}' -f $_ }) -join ' '
    '0x{0:x16}: {1}' -f ($Address + [uint64]$offset), $hex
}