The Topcat display cards are not user configurable. If one is present on a system, it will always have a frame buffer address of 0x200000 and a control register address of 0x560000. These are the HP series 300 ITE (Internal Terminal Emulator) defaults. The device can also be used as a graphics output device.
The ioctl(2) calls supported by the BSD system for the Topcat are:
Get info about device, setting the entries in the grfinfo structure, as defined in Aq Pa hpdev/grfioctl.h . For the 98544 or 98549, the number of planes should be 1, as they are monochrome devices. The number of planes for a 98545 is 4, translating to 15 colors, excluding black. The 98547 and 98548 cards have 6 planes, yielding 63 colors and black. The 98550 has 8 planes, yielding 255 colors and black. The displayed frame buffer size for the 98549 and 98550 is 2048 x 1024, for the others it is 1024 x 768.
Turn graphics on by enabling CRT output. The screen will come on, displaying whatever is in the frame buffer, using whatever colormap is in place.
Turn graphics off by disabling output to the CRT The frame buffer contents are not affected.
Map in control registers and framebuffer space. Once the device file is mapped, the frame buffer structure is accessible. The frame buffer structure describing Topcat/Catseye devices is defined in Aq Pa hpdev/grf_tcreg.h .
For further information about the use of ioctl see the man page.
struct tcboxfb *tc; u_char *Addr, frame_buffer; struct grfinfo gi; int disp_fd; disp_fd = open("/dev/grf0",1); if (ioctl (disp_fd, GRFIOCGINFO, &gi) < 0) return -1; (void) ioctl (disp_fd, GRFIOCON, 0); Addr = (u_char *) 0; if (ioctl (disp_fd, GRFIOCMAP, &Addr) < 0) { (void) ioctl (disp_fd, GRFIOCOFF, 0); return -1; } tc = (tcboxfb *) Addr; /* Control Registers */ frame_buffer = (u_char *) Addr + gi.gd_regsize; /* Frame buffer memory */