Friday, July 16, 2021

Keeping the Upscale and Capture Pure - The RGB2HDMI and Digital PC Video Standards

When IBM was designing video display adapters for its IBM PC, it treated video quality as important.  While the world of displays was in 1980 essentially analog, IBM chose to use digital outputs for its IBM Monochrome Display and Printer Adapter and Color Graphics Adapter.  Later it continued to use a digital TTL interface for the IBM PCjr.'s built in video and its Enhanced Graphics Adapters.  Competitors and copycats, like the Hercules Graphics Card and the Tandy 1000's built-in video, also copied IBM's usage of the DE-9 port carrying digital color signals.  While some of the color cards had composite color video support, serious business usage demanded the use of a monitor which could accept those digital signals for the highest possible picture quality possible.  

By 1987, the limitations of the digital interface, with each color primary requiring a separate collection of wires, was too limiting for IBM's Video Graphics Array.  The connector was changed and the colors were output over an analog interface, which only required one pin per color primary.  The VGA analog video standard remained the principal way by which PCs connected their displays for over fifteen years.  By the time the digital DVI connector became popular enough to replace VGA, the older pre-VGA standards had been long consigned to the realm of retro-computing.  

Today the modern display device tends to eschew any display standard older than DVI, with most only having HDMI and DisplayPort inputs.  The digital standards of old used special CRTs, which have become expensive and often require repair or restoration due to age.  Those of us who enjoy working on retro computers are faced with having to "settle" for composite video, having to fork out large amounts of money and space for the special digital CRTs displays or use rather particular capture cards to see what was intended.  The RGB2HDMI is one really good solution for these issues, let's take a look at it.

Tuesday, July 13, 2021

Lag : Consoles, Emulators, FPGAs

When playing classic video games on non-original hardware, one should always be conscious for the amount of extra lag that method may offer over the original hardware.  Along with accuracy, latency is one of the most important tangible benefits (versus of using original hardware and display technology (CRTs) over emulators and current display technology (LCDs).  Latency has always existed in some form, and in this article I will give an overview on how latency has evolved over time.  

Additionally, the use of FPGA chips to simulate original hardware has become increasingly popular over the past five years.  FPGAs can offer the benefit of lower latency compared to traditional software based emulation and can offer a high degree of accuracy by using relatively inexpensive hardware.  FPGAs are not without their singular issues, and in this article I will go over some of the issues with using FPGAs as a replacement for original hardware.