Differences

This shows you the differences between two versions of the page.

--- blog:pc98_devcode [2020/08/22 10:35] – [NEC PC-98 C Code Examples] john
+++ blog:pc98_devcode [2020/08/22 10:48] (current) – [PC-9821 PEGC 256 Colour Graphics Hardware] john
@@ Line 49: / Line 49: @@
 ===== PC-9821 PEGC 256 Colour Graphics Hardware =====
+There are several generations of custom graphics hardware on the PC-98:
+     * PC-9801, GDC: 640x400, 8 colour, 96KB VRAM (later 192KB)
+     * PC-9801VF, GC: 640x400, 16 colour, 96KB VRAM (later 192KB)
+     * PC-9801VX, EGC: 640x400, 16 colour, 256KB VRAM, added raster operation functions, bitblt and bit shift functions
+     * PC-9821AP, PEGC: 640x400, 256 colour, 512KB VRAM, added packed-pixel and planar addressing modes
+The systems are //generally// backwards compatible, so a PC-9821 //should// be able to run software designed for early PC-9801 machines... cpu speed dependent, of course.
+My focus is on the later PEGC, 256 colour systems, since (a) this is the hardware I actually own, and (b), its most similar to DOS VGA or modern framebuffer hardware.
 ==== Packed-Pixel or Chunky Video Modes ====