program to run

  local primaryGPUAddr = "b4e"
  local primaryScreenAddr = "d48"
  local fs = require("filesystem")
  local component = require("component")

-- 1) MOUNT HARD DRIVE & VERIFY SUCCESS
  local address = ...
  local hdCheck, hdError = fs.mount(address, "/main")
  if hdCheck then
    db("1) Mounted hard drive under '/main'")
  else
    db("1) Hard Drive did NOT mount: " .. tostring(hdError))
  end

-- 2) SET PRIMARY GPU
-- (a) Checks address of randomly-chosen primary GPU:
  if component.isAvailable("gpu") then
    db("2(a) Primary GPU exists at Boot: " .. tostring(component.gpu.address))
  end

-- (b) Change primary GPU:
  primaryGPUAddr = component.get(primaryGPUAddr) -- resolve full GPU address
  db("2(b) Setting Primary GPU to: " .. tostring(primaryGPUAddr))
  component.setPrimary("gpu",primaryGPUAddr)

-- (c) Check again whether primary GPU exists:
  if component.isAvailable("gpu") then
    db("2(c) Primary GPU successfully changed: " .. tostring(component.gpu.address))
  else
    db("2(c) No Primary GPU!")
    db("... GPU Address = (" .. tostring(component.gpu.address) .. ")")
  end

-- 3) BIND PRIMARY GPU TO "TERMINAL" SCREEN:
  primaryScreenAddr = component.get(primaryScreenAddr) -- resolve full screen address
  local gpu = component.gpu
  db("3) Attempting Screen Bind: " .. tostring(gpu.bind(primaryScreenAddr)))