Cost-effective programmable display controller for medical imaging

A cost-effective display system has been developed and incorporated into a low-cost magnetic resonance imager. A single graphics board (Peritek VCD) with an on-board 68030 CPU, ACRTC graphics controller and 1024 X 1024 12 bit video RAM is interfaced to a DEC Micro-VAX II host computer. All memory and devices on the graphics board are designed to be tri-ported so that they may be accessed by all three processing engines: 68030, VAX, and ACRTC with minimum arbitration delay. The software is designed to time share between the processing engines to provide maximum throughput without overloading the host CPU. Using the on-board hardware zoom of 2, the available video RAM can be partitioned to allow 16 frame movie loops to be produced. The ACRTC graphics controller allows other video modes such as PAL and NTSC to be selected by software control. This allows direct video taping without the expense and resolution degradation of scan convertors or secondary filming off the monitor screen. A direct pathway off the graphics board to a digital laser camera is also provided. This system is also applicable to workstation displays where it would not be the primary display but could be used for the tasks which workstations can not do such as interfacing to analog multiformat cameras, videotape recorders, and digital laser cameras.