CMM2 - Go Go Go!!!!


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Mixtel90

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Joined: 05/10/2019
Location: United Kingdom
Posts: 1526
Posted: 12:28pm 19 Nov 2021      

The old Vectrex game drove the X and Y plates and the cathode of the CRT directly IIRC. That allowed very fast control over the line with instant on and off at the beginning and end. It was a true vector display.

Not all oscilloscopes give you that much access now, particularly to a blanking control input.

The BBC did its line drawing using integer variables, which ran a lot faster than FP variables on that machine. They used a simple XOR command to plot to the screen and ignored the last dot of closed shapes so that it didn't get erased again. The routines appear to be in BASIC, not asm.