![]() ![]() The arcade hardware uses resistor ladders to convert 4x3 bit RGB+H+V sync digital signals into analog, this is a typical model for the period. In the end to get some clarity on the sprite plotting specifically I started to transcribe what was thought to be the sprite logic portion of the schematic into Proteus, since it can simulate digital electronics really well. A friend and I were discussing the clock speed and fill-rate while trying to deduce the operation of the hardware just by inspecting the hand drawn schematics, as you do. I was looking at Bomb Jack boards on ebay and pondering how they had enough fill-rate to draw 24 16x16 sprites and have the option for some to use 32x32 mode as well. Truth be told, the Imagine hardware was pretty much just extra RAM but this was a fun project to see how far the arcade hardware was pushing the limits of board size and signal complexity. Since this hardware uses TTL logic available back from the same time period I was wondering exactly how much extra graphical grunt could have been engineered and interfaced with these old 8-bit computers. ![]() In the back of my mind was the often fabled "Mega games" by Imagine Software which were planned to use extra hardware on the Spectrum and Commodore 64 to augment the machine's capabilities. This project started when old retro arcade hardware was being discussed. Background colour select (Can be rapidly updated during the frame for plasma effects).Background "mode7" screen that allows per-pixel affine transformation.64圆4 Tile X/Y offset, useful for fast hardware scrolling.Now since V2.0 the hardware has progressed to add extra features not present in the original, such as: The version 1.0 of this work was approximately interface pin and chip compatible with the original hardware schematic. Why bother, you're probably asking? Well if you have to ask then perhaps you're not the right audience. This started life as a working schematic for the video display portion of the original Bomb Jack arcade hardware. Mostly using these tags: #MegaWang #RetroTTL #RetroTTLVideoCard #C64 #Commodore64 #electronics. ![]() Main social media: Don't have a Mastodon account? Click here for an invitation link:. ![]()
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