1 VGA - VGA is an analog output, and was most common in the CRT-era of computer displays. It has largely been phased out of any recent hardware, but you may encounter it with older computers or CRT monitors.  DisplayPort - This is a digital connection, similar to HDMI.
There is evidence that iron was known from before 5000 BCE. The oldest known iron objects used by humans are some beads of meteoric iron, made in Egypt in about 4000 BCE. The discovery of smelting around 3000 BCE led to the start of the iron age around 1200 BCE and the prominent use of iron for tools and weapons.
The Iron Age The first invention of steel was in 13th century BC - Invention of steel when iron and charcoal are combined properly. If you mean by the mass production of steel, it was 1855 by Henry Bessemer, who invented the Bessemer process. There have been some research into the history of metallurgy and it is quite likely that the science of making steel was known in India as earlier that 4th century, There are pillars made in 4th century AD that still stand as proof.