HSP stands for Horizontal Screen Positioning, but it's also well known with the acronym VSP (Variable Screen Positioning), as named the very first time in the "VSP+IK" demo released on C64 by The Mean Team. Other known names are: DMA-delay and Wanker, where the latter unfortunate name was probably mis-translated from the German word "wanken", meaning "to waver", which is what the graphic usually did.
HSP allows arbitrary x-placement of a bitmap, with the bitmap wrapping around at the border. That can be performed by wasting a controlled number of cycles in order to delay the screen memory printing, instead of copying a whole new shifted screen. Every single cycle counts on the screen as one character. Hence, changing the horizontal scrolling ($FF07) it results overall in a time-saving horizontal screen movement.
BSZ sits on the coders'throne, with this 2 screens HSP shown in Questionmark trackmo.
hsp,horizontal screen positioning,vsp,variable screen positioning,dma-delay,wanker
Copyright © Plus/4 World Team, 2001-2018