PORTIBM PC Portable (uses same BIOS as XT) 03B0-03BF - MDA(Monochrome Display Adapter) A text-only video adapter introduced together with the original IBMInternational Busiuness Machines PCIBM PC. See also CGAColor Graphics Adapter, HGC. (Monochrome Display Adapter based on 6845) 03B0 -W same as 03B4 03B1 RW same as 03B5 03B2 -W same as 03B4 03B3 RW same as 03B5 03B4 -W MDA(Monochrome Display Adapter) A text-only video adapter introduced together with the original IBMInternational Busiuness Machines PCIBM PC. See also CGAColor Graphics Adapter, HGC. CRT index register (MDA(Monochrome Display Adapter) A text-only video adapter introduced together with the original IBMInternational Busiuness Machines PCIBM PC. See also CGAColor Graphics Adapter, HGC./mono EGAEnhanced Graphics Adapter(Enhanced Graphics Adapter) IBMInternational Busiuness Machines's second color video board for the IBMInternational Busiuness Machines PCIBM PC family, capable of a maximum resolution of 640x350 pixels in 16 simultaneous colors of a total of 64 possible colors./mono VGAVideo Graphics Array(Video Graphics Array) The video adapter introduced with the IBMInternational Busiuness Machines PS/2IBM PS/2, any model series of computers.) selects which register (0-11h) is to be accessed through 03B5h Note: this port is read/write on some VGAs bit7-6: (VGAVideo Graphics Array(Video Graphics Array) The video adapter introduced with the IBMInternational Busiuness Machines PS/2IBM PS/2, any model series of computers.) reserved (0) bit5 : (VGAVideo Graphics Array(Video Graphics Array) The video adapter introduced with the IBMInternational Busiuness Machines PS/2IBM PS/2, any model series of computers.) reserved for testing (0) bit4-0: selects which register is to be accessed through 03B5h 03B5 RW MDA(Monochrome Display Adapter) A text-only video adapter introduced together with the original IBMInternational Busiuness Machines PCIBM PC. See also CGAColor Graphics Adapter, HGC. CRT data register (MDA(Monochrome Display Adapter) A text-only video adapter introduced together with the original IBMInternational Busiuness Machines PCIBM PC. See also CGAColor Graphics Adapter, HGC./mono EGAEnhanced Graphics Adapter(Enhanced Graphics Adapter) IBMInternational Busiuness Machines's second color video board for the IBMInternational Busiuness Machines PCIBM PC family, capable of a maximum resolution of 640x350 pixels in 16 simultaneous colors of a total of 64 possible colors./mono VGAVideo Graphics Array(Video Graphics Array) The video adapter introduced with the IBMInternational Busiuness Machines PS/2IBM PS/2, any model series of computers.) (see #P0654,#P0708) selected by PORTIBM PC Portable (uses same BIOS as XT) 03B4h. registers 0C-0F may be read Color adapters are at 3D4/3D5, but are mentioned here for better overview. There are differences in names and some bits functionality on EGAEnhanced Graphics Adapter(Enhanced Graphics Adapter) IBMInternational Busiuness Machines's second color video board for the IBMInternational Busiuness Machines PCIBM PC family, capable of a maximum resolution of 640x350 pixels in 16 simultaneous colors of a total of 64 possible colors., VGAVideo Graphics Array(Video Graphics Array) The video adapter introduced with the IBMInternational Busiuness Machines PS/2IBM PS/2, any model series of computers. in their native modes, but clones in their emulation modes emulate the original 6845 at bit level. The default values are for MDA(Monochrome Display Adapter) A text-only video adapter introduced together with the original IBMInternational Busiuness Machines PCIBM PC. See also CGAColor Graphics Adapter, HGC., HGC(Hercules Graphics Card) A monochrome video adapter capable of 720x352 monochrome graphics. The HGC was the first non-IBM video adapter for the IBMInternational Busiuness Machines PCIBM PC. See also CGAColor Graphics Adapter, MDA., CGAColor Graphics Adapter(Color/Graphics Adapter) One of the two video display boards introduced together with the original IBMInternational Busiuness Machines PCIBM PC. See also HGC, MDA. only, if not otherwise mentioned. 03B6 -W same as 03B4h 03B7 RW same as 03B5h 03B8 rW MDA(Monochrome Display Adapter) A text-only video adapter introduced together with the original IBMInternational Busiuness Machines PCIBM PC. See also CGAColor Graphics Adapter, HGC. mode control register (see #P0655) 03B9 ?W reserved for color select register on color adapter 03B9 -W MDA(Monochrome Display Adapter) A text-only video adapter introduced together with the original IBMInternational Busiuness Machines PCIBM PC. See also CGAColor Graphics Adapter, HGC./HGC(Hercules Graphics Card) A monochrome video adapter capable of 720x352 monochrome graphics. The HGC was the first non-IBM video adapter for the IBMInternational Busiuness Machines PCIBM PC. See also CGAColor Graphics Adapter, MDA.: set lightpen flipflop (value written is ignored) cannot be found on native mono EGAEnhanced Graphics Adapter(Enhanced Graphics Adapter) IBMInternational Busiuness Machines's second color video board for the IBMInternational Busiuness Machines PCIBM PC family, capable of a maximum resolution of 640x350 pixels in 16 simultaneous colors of a total of 64 possible colors., mono VGAVideo Graphics Array(Video Graphics Array) The video adapter introduced with the IBMInternational Busiuness Machines PS/2IBM PS/2, any model series of computers. (without translation ROM(Read-Only Memory) A memory for program storage which may not be changed by the program as it runs.) 03BA R- CRT status register (see #P0656) (EGAEnhanced Graphics Adapter(Enhanced Graphics Adapter) IBMInternational Busiuness Machines's second color video board for the IBMInternational Busiuness Machines PCIBM PC family, capable of a maximum resolution of 640x350 pixels in 16 simultaneous colors of a total of 64 possible colors./VGAVideo Graphics Array(Video Graphics Array) The video adapter introduced with the IBMInternational Busiuness Machines PS/2IBM PS/2, any model series of computers.) input status 1 register 03BA -W (mono EGAEnhanced Graphics Adapter(Enhanced Graphics Adapter) IBMInternational Busiuness Machines's second color video board for the IBMInternational Busiuness Machines PCIBM PC family, capable of a maximum resolution of 640x350 pixels in 16 simultaneous colors of a total of 64 possible colors./mono VGAVideo Graphics Array(Video Graphics Array) The video adapter introduced with the IBMInternational Busiuness Machines PS/2IBM PS/2, any model series of computers.) feature control register (see PORTIBM PC Portable (uses same BIOS as XT) 03DAh-W for details; VGAVideo Graphics Array(Video Graphics Array) The video adapter introduced with the IBMInternational Busiuness Machines PS/2IBM PS/2, any model series of computers., see PORTIBM PC Portable (uses same BIOS as XT) 03CAh-R) 03BB -W light pen strobe reset (on any value) (Table P0654) Values for mono video adapter CRT data register index: defaults: MDA(Monochrome Display Adapter) A text-only video adapter introduced together with the original IBMInternational Busiuness Machines PCIBM PC. See also CGAColor Graphics Adapter, HGC./HGC(Hercules Graphics Card) A monochrome video adapter capable of 720x352 monochrome graphics. The HGC was the first non-IBM video adapter for the IBMInternational Busiuness Machines PCIBM PC. See also CGAColor Graphics Adapter, MDA. HGC(Hercules Graphics Card) A monochrome video adapter capable of 720x352 monochrome graphics. The HGC was the first non-IBM video adapter for the IBMInternational Busiuness Machines PCIBM PC. See also CGAColor Graphics Adapter, MDA. CGAColor Graphics Adapter(Color/Graphics Adapter) One of the two video display boards introduced together with the original IBMInternational Busiuness Machines PCIBM PC. See also HGC, MDA. CGAColor Graphics Adapter(Color/Graphics Adapter) One of the two video display boards introduced together with the original IBMInternational Busiuness Machines PCIBM PC. See also HGC, MDA. CGAColor Graphics Adapter(Color/Graphics Adapter) One of the two video display boards introduced together with the original IBMInternational Busiuness Machines PCIBM PC. See also HGC, MDA. text graph text1 text2 graph 7 720x348 1 3 5,6 00h horizontal total 61h 35h 38h 71h 38h ET4000: in VGAVideo Graphics Array(Video Graphics Array) The video adapter introduced with the IBMInternational Busiuness Machines PS/2IBM PS/2, any model series of computers. mode scanlines-5 in EGAEnhanced Graphics Adapter(Enhanced Graphics Adapter) IBMInternational Busiuness Machines's second color video board for the IBMInternational Busiuness Machines PCIBM PC family, capable of a maximum resolution of 640x350 pixels in 16 simultaneous colors of a total of 64 possible colors. mode scanlines-2 01h horizontal displayed 50h 2Dh 28h 50h 28h horizontal display end-1 (EGAEnhanced Graphics Adapter(Enhanced Graphics Adapter) IBMInternational Busiuness Machines's second color video board for the IBMInternational Busiuness Machines PCIBM PC family, capable of a maximum resolution of 640x350 pixels in 16 simultaneous colors of a total of 64 possible colors.,VGAVideo Graphics Array(Video Graphics Array) The video adapter introduced with the IBMInternational Busiuness Machines PS/2IBM PS/2, any model series of computers.) 02h horizontal sync position 52h 2Eh 2Dh 5Ah/5Ch 2Dh 03h sync pulse width 0Fh 07h/0Fh 0Ah 0Ah 0Ah bit7-4 vsync, bit3-0 hsync end horizontal blanking (EGAEnhanced Graphics Adapter(Enhanced Graphics Adapter) IBMInternational Busiuness Machines's second color video board for the IBMInternational Busiuness Machines PCIBM PC family, capable of a maximum resolution of 640x350 pixels in 16 simultaneous colors of a total of 64 possible colors.,VGAVideo Graphics Array(Video Graphics Array) The video adapter introduced with the IBMInternational Busiuness Machines PS/2IBM PS/2, any model series of computers.) VGAVideo Graphics Array(Video Graphics Array) The video adapter introduced with the IBMInternational Busiuness Machines PS/2IBM PS/2, any model series of computers. : bit7=1 : enable read access to regs 10h, 11h (otherwise VGAVideo Graphics Array(Video Graphics Array) The video adapter introduced with the IBMInternational Busiuness Machines PS/2IBM PS/2, any model series of computers. clones may show lightpen values) EGAEnhanced Graphics Adapter(Enhanced Graphics Adapter) IBMInternational Busiuness Machines's second color video board for the IBMInternational Busiuness Machines PCIBM PC family, capable of a maximum resolution of 640x350 pixels in 16 simultaneous colors of a total of 64 possible colors.,VGAVideo Graphics Array(Video Graphics Array) The video adapter introduced with the IBMInternational Busiuness Machines PS/2IBM PS/2, any model series of computers.: bit6-5=0-3: display enable skew control bit4-0 : end blanking 04h vertical total (vcycle-1) 19h 5Bh 1Fh 1Fh 7Fh bit7 only used on MCGAMulti-Color Graphics Array(Multi-Color Graphics Array) The low-end color adapter offered in IBMInternational Busiuness Machines's early PS/2IBM PS/2, any model series machines. start horizontal retrace (EGAEnhanced Graphics Adapter(Enhanced Graphics Adapter) IBMInternational Busiuness Machines's second color video board for the IBMInternational Busiuness Machines PCIBM PC family, capable of a maximum resolution of 640x350 pixels in 16 simultaneous colors of a total of 64 possible colors., VGAVideo Graphics Array(Video Graphics Array) The video adapter introduced with the IBMInternational Busiuness Machines PS/2IBM PS/2, any model series of computers.) Genoa SuperEGA only???: bit7 : start at odd memory address bit6-5: horizontal sync skew bit4-0: start retrace+ retrace width 05h vertical total adjust 06h 02h 06h 06h 06h bit7-5 only used on MCGAMulti-Color Graphics Array(Multi-Color Graphics Array) The low-end color adapter offered in IBMInternational Busiuness Machines's early PS/2IBM PS/2, any model series machines. end horizontal retrace (EGAEnhanced Graphics Adapter(Enhanced Graphics Adapter) IBMInternational Busiuness Machines's second color video board for the IBMInternational Busiuness Machines PCIBM PC family, capable of a maximum resolution of 640x350 pixels in 16 simultaneous colors of a total of 64 possible colors., VGAVideo Graphics Array(Video Graphics Array) The video adapter introduced with the IBMInternational Busiuness Machines PS/2IBM PS/2, any model series of computers.) bit7 : (EGAEnhanced Graphics Adapter(Enhanced Graphics Adapter) IBMInternational Busiuness Machines's second color video board for the IBMInternational Busiuness Machines PCIBM PC family, capable of a maximum resolution of 640x350 pixels in 16 simultaneous colors of a total of 64 possible colors.) start at odd memory address (VGAVideo Graphics Array(Video Graphics Array) The video adapter introduced with the IBMInternational Busiuness Machines PS/2IBM PS/2, any model series of computers.) bit5 of end horizontal retrace bit6-5: horizontal sync skew bit4-0: end horizontal retrace 06h vertical displayed 19h 57h 19h 19h 64h bit7 only used on MCGAMulti-Color Graphics Array(Multi-Color Graphics Array) The low-end color adapter offered in IBMInternational Busiuness Machines's early PS/2IBM PS/2, any model series machines. (EGAEnhanced Graphics Adapter(Enhanced Graphics Adapter) IBMInternational Busiuness Machines's second color video board for the IBMInternational Busiuness Machines PCIBM PC family, capable of a maximum resolution of 640x350 pixels in 16 simultaneous colors of a total of 64 possible colors.) vertical total-1 (VGAVideo Graphics Array(Video Graphics Array) The video adapter introduced with the IBMInternational Busiuness Machines PS/2IBM PS/2, any model series of computers.) vertical total-2 07h vertical sync pulse width-1 19h 57h 1Ch 1Ch 70h/66h bit7 only used on MCGAMulti-Color Graphics Array(Multi-Color Graphics Array) The low-end color adapter offered in IBMInternational Busiuness Machines's early PS/2IBM PS/2, any model series machines. controller overflow (EGAEnhanced Graphics Adapter(Enhanced Graphics Adapter) IBMInternational Busiuness Machines's second color video board for the IBMInternational Busiuness Machines PCIBM PC family, capable of a maximum resolution of 640x350 pixels in 16 simultaneous colors of a total of 64 possible colors.,VGAVideo Graphics Array(Video Graphics Array) The video adapter introduced with the IBMInternational Busiuness Machines PS/2IBM PS/2, any model series of computers.) bit7: (VGAVideo Graphics Array(Video Graphics Array) The video adapter introduced with the IBMInternational Busiuness Machines PS/2IBM PS/2, any model series of computers.) bit9 of start vertical retrace (10h) bit6: (VGAVideo Graphics Array(Video Graphics Array) The video adapter introduced with the IBMInternational Busiuness Machines PS/2IBM PS/2, any model series of computers.) bit9 of vertical display end (12h) bit5: (VGAVideo Graphics Array(Video Graphics Array) The video adapter introduced with the IBMInternational Busiuness Machines PS/2IBM PS/2, any model series of computers.) bit9 of vertical total (06h) (EGAEnhanced Graphics Adapter(Enhanced Graphics Adapter) IBMInternational Busiuness Machines's second color video board for the IBMInternational Busiuness Machines PCIBM PC family, capable of a maximum resolution of 640x350 pixels in 16 simultaneous colors of a total of 64 possible colors.) bit5 of cursor-position (0Ah) bit4: bit8 of line compare (18h) bit3: bit8 of start vertical blanking (15h) bit2: bit8 of vertical retrace start (10h) bit1: bit8 of vertical display end (12h) bit0: bit8 of vertical total (06h) 08h interlace mode (not MCGAMulti-Color Graphics Array(Multi-Color Graphics Array) The low-end color adapter offered in IBMInternational Busiuness Machines's early PS/2IBM PS/2, any model series machines.) 02h 02h 02h 02h 02h bit7-2: reserved bit1 : delay bit0=1: interlace on preset row scan (EGAEnhanced Graphics Adapter(Enhanced Graphics Adapter) IBMInternational Busiuness Machines's second color video board for the IBMInternational Busiuness Machines PCIBM PC family, capable of a maximum resolution of 640x350 pixels in 16 simultaneous colors of a total of 64 possible colors., VGAVideo Graphics Array(Video Graphics Array) The video adapter introduced with the IBMInternational Busiuness Machines PS/2IBM PS/2, any model series of computers.) bit7 : reserved bit6-5: (VGAVideo Graphics Array(Video Graphics Array) The video adapter introduced with the IBMInternational Busiuness Machines PS/2IBM PS/2, any model series of computers.) byte panning (low-order bits of display start addr in odd/even and quad modes bit4-0: start row scan after retrace 09h maximum scan lines 0Dh 03h 07h 07h 01h bit7 : (VGAVideo Graphics Array(Video Graphics Array) The video adapter introduced with the IBMInternational Busiuness Machines PS/2IBM PS/2, any model series of computers.) double scan active bit6 : (VGAVideo Graphics Array(Video Graphics Array) The video adapter introduced with the IBMInternational Busiuness Machines PS/2IBM PS/2, any model series of computers.) bit9 of line compare (18h) bit5 : (VGAVideo Graphics Array(Video Graphics Array) The video adapter introduced with the IBMInternational Busiuness Machines PS/2IBM PS/2, any model series of computers.) bit9 of start vertical blanking (15h) bit4-0: maximum scan line 00..31 (height-1) 0Ah cursor start 0Bh 00h 06h 06h 06h/00h bit7 : reserved bit6-5: original 6845: cursor on/off, blink interval (not on all adapters, as original MDA(Monochrome Display Adapter) A text-only video adapter introduced together with the original IBMInternational Busiuness Machines PCIBM PC. See also CGAColor Graphics Adapter, HGC., CGAColor Graphics Adapter(Color/Graphics Adapter) One of the two video display boards introduced together with the original IBMInternational Busiuness Machines PCIBM PC. See also HGC, MDA. have extra circuitrity to avoid this!!) bit6-5: native EGAEnhanced Graphics Adapter(Enhanced Graphics Adapter) IBMInternational Busiuness Machines's second color video board for the IBMInternational Busiuness Machines PCIBM PC family, capable of a maximum resolution of 640x350 pixels in 16 simultaneous colors of a total of 64 possible colors.: not used bit6 : (VGAVideo Graphics Array(Video Graphics Array) The video adapter introduced with the IBMInternational Busiuness Machines PS/2IBM PS/2, any model series of computers.) not used bit5=0: (VGAVideo Graphics Array(Video Graphics Array) The video adapter introduced with the IBMInternational Busiuness Machines PS/2IBM PS/2, any model series of computers.) cursor on bit4-0: first cursor scanline 0Bh cursor end 0Ch 00h 07h 07h 07h/00h bit7 : reserved bit6-5: EGAEnhanced Graphics Adapter(Enhanced Graphics Adapter) IBMInternational Busiuness Machines's second color video board for the IBMInternational Busiuness Machines PCIBM PC family, capable of a maximum resolution of 640x350 pixels in 16 simultaneous colors of a total of 64 possible colors., VGAVideo Graphics Array(Video Graphics Array) The video adapter introduced with the IBMInternational Busiuness Machines PS/2IBM PS/2, any model series of computers.: cursor skew control bit4-0: end cursor row 0Ch RW start address high 00h 00h 00h 00h 00h bit7-6 not used by original 6845 (MDA(Monochrome Display Adapter) A text-only video adapter introduced together with the original IBMInternational Busiuness Machines PCIBM PC. See also CGAColor Graphics Adapter, HGC.,HGC(Hercules Graphics Card) A monochrome video adapter capable of 720x352 monochrome graphics. The HGC was the first non-IBM video adapter for the IBMInternational Busiuness Machines PCIBM PC. See also CGAColor Graphics Adapter, MDA.,CGAColor Graphics Adapter(Color/Graphics Adapter) One of the two video display boards introduced together with the original IBMInternational Busiuness Machines PCIBM PC. See also HGC, MDA.) 0Dh RW start address low 00h 00h 00h 00h 00h 0Eh RW cursor location high 00h 00h 00h 00h 00h bit7-4 not used by original 6845 (MDA(Monochrome Display Adapter) A text-only video adapter introduced together with the original IBMInternational Busiuness Machines PCIBM PC. See also CGAColor Graphics Adapter, HGC.,HGC(Hercules Graphics Card) A monochrome video adapter capable of 720x352 monochrome graphics. The HGC was the first non-IBM video adapter for the IBMInternational Busiuness Machines PCIBM PC. See also CGAColor Graphics Adapter, MDA.,CGAColor Graphics Adapter(Color/Graphics Adapter) One of the two video display boards introduced together with the original IBMInternational Busiuness Machines PCIBM PC. See also HGC, MDA.) bit5-4 reserved on MCGAMulti-Color Graphics Array(Multi-Color Graphics Array) The low-end color adapter offered in IBMInternational Busiuness Machines's early PS/2IBM PS/2, any model series machines. 0Fh RW cursor location low 00h 00h 00h 00h 00h 10h R- light pen high (MDA(Monochrome Display Adapter) A text-only video adapter introduced together with the original IBMInternational Busiuness Machines PCIBM PC. See also CGAColor Graphics Adapter, HGC./CGAColor Graphics Adapter(Color/Graphics Adapter) One of the two video display boards introduced together with the original IBMInternational Busiuness Machines PCIBM PC. See also HGC, MDA./EGAEnhanced Graphics Adapter(Enhanced Graphics Adapter) IBMInternational Busiuness Machines's second color video board for the IBMInternational Busiuness Machines PCIBM PC family, capable of a maximum resolution of 640x350 pixels in 16 simultaneous colors of a total of 64 possible colors. only, some HGC(Hercules Graphics Card) A monochrome video adapter capable of 720x352 monochrome graphics. The HGC was the first non-IBM video adapter for the IBMInternational Busiuness Machines PCIBM PC. See also CGAColor Graphics Adapter, MDA., few VGAVideo Graphics Array(Video Graphics Array) The video adapter introduced with the IBMInternational Busiuness Machines PS/2IBM PS/2, any model series of computers. clones in emulation, not with ET4000) 10h R- MCGAMulti-Color Graphics Array(Multi-Color Graphics Array) The low-end color adapter offered in IBMInternational Busiuness Machines's early PS/2IBM PS/2, any model series machines. at 3D5h only: mode control status register (see #P0711) 11h R- light pen low (MDA(Monochrome Display Adapter) A text-only video adapter introduced together with the original IBMInternational Busiuness Machines PCIBM PC. See also CGAColor Graphics Adapter, HGC./CGAColor Graphics Adapter(Color/Graphics Adapter) One of the two video display boards introduced together with the original IBMInternational Busiuness Machines PCIBM PC. See also HGC, MDA./EGAEnhanced Graphics Adapter(Enhanced Graphics Adapter) IBMInternational Busiuness Machines's second color video board for the IBMInternational Busiuness Machines PCIBM PC family, capable of a maximum resolution of 640x350 pixels in 16 simultaneous colors of a total of 64 possible colors. only, some HGC(Hercules Graphics Card) A monochrome video adapter capable of 720x352 monochrome graphics. The HGC was the first non-IBM video adapter for the IBMInternational Busiuness Machines PCIBM PC. See also CGAColor Graphics Adapter, MDA., few VGAVideo Graphics Array(Video Graphics Array) The video adapter introduced with the IBMInternational Busiuness Machines PS/2IBM PS/2, any model series of computers. clones in emulation, not with ET4000) 14h -W HGC+,InColor: xMode register 15h -W HGC+,InColor: underscore register 16h -W HGC+,InColor: overstrike register 17h -W InColor: exception register 18h -W InColor: plane mask register 19h -W InColor: read/write control register 1Ah -W InColor: read/write color register 1Bh -W InColor: Latch Protect register 1Ch RW InColor: palette register Notes: registers 10h and 11h have varying uses on VGAVideo Graphics Array(Video Graphics Array) The video adapter introduced with the IBMInternational Busiuness Machines PS/2IBM PS/2, any model series of computers. (see #P0708) and MCGAMulti-Color Graphics Array(Multi-Color Graphics Array) The low-end color adapter offered in IBMInternational Busiuness Machines's early PS/2IBM PS/2, any model series machines. (see #P0710) MDA(Monochrome Display Adapter) A text-only video adapter introduced together with the original IBMInternational Busiuness Machines PCIBM PC. See also CGAColor Graphics Adapter, HGC., HGC(Hercules Graphics Card) A monochrome video adapter capable of 720x352 monochrome graphics. The HGC was the first non-IBM video adapter for the IBMInternational Busiuness Machines PCIBM PC. See also CGAColor Graphics Adapter, MDA., CGAColor Graphics Adapter(Color/Graphics Adapter) One of the two video display boards introduced together with the original IBMInternational Busiuness Machines PCIBM PC. See also HGC, MDA.: 6845 registers 00h-0Dh are write only, 0Eh, 0Fh are r/w, and 10h-11h are read only. The alternative initial defaults may be used sometimes on modern adapters. HGC+(RamFont): as with HGC(Hercules Graphics Card) A monochrome video adapter capable of 720x352 monochrome graphics. The HGC was the first non-IBM video adapter for the IBMInternational Busiuness Machines PCIBM PC. See also CGAColor Graphics Adapter, MDA., but 3 additional registers for font control emulations : more registers may be r/w, but most often it's the same as with native 6845. MCGAMulti-Color Graphics Array(Multi-Color Graphics Array) The low-end color adapter offered in IBMInternational Busiuness Machines's early PS/2IBM PS/2, any model series machines. (CGA+) : Though this is a mixture of CGAColor Graphics Adapter(Color/Graphics Adapter) One of the two video display boards introduced together with the original IBMInternational Busiuness Machines PCIBM PC. See also HGC, MDA. and VGAVideo Graphics Array(Video Graphics Array) The video adapter introduced with the IBMInternational Busiuness Machines PS/2IBM PS/2, any model series of computers., most registers are same as with CGAColor Graphics Adapter(Color/Graphics Adapter) One of the two video display boards introduced together with the original IBMInternational Busiuness Machines PCIBM PC. See also HGC, MDA., but with some enhancements and incompatibilities to EGAEnhanced Graphics Adapter(Enhanced Graphics Adapter) IBMInternational Busiuness Machines's second color video board for the IBMInternational Busiuness Machines PCIBM PC family, capable of a maximum resolution of 640x350 pixels in 16 simultaneous colors of a total of 64 possible colors., VGAVideo Graphics Array(Video Graphics Array) The video adapter introduced with the IBMInternational Busiuness Machines PS/2IBM PS/2, any model series of computers.. native EGAEnhanced Graphics Adapter(Enhanced Graphics Adapter) IBMInternational Busiuness Machines's second color video board for the IBMInternational Busiuness Machines PCIBM PC family, capable of a maximum resolution of 640x350 pixels in 16 simultaneous colors of a total of 64 possible colors. : registers 00h-0Bh are write only, 0Ch-0Fh are r/w, 10h-11h are read/write, 12h-18h are write only. More regs may be r/w on enhanced clones. GenoaSuperEGA: adapter with chips SEQCRT GN006001 and GRAT GN006002, e.g. c't Super-EGA adapter. Is EGAEnhanced Graphics Adapter(Enhanced Graphics Adapter) IBMInternational Busiuness Machines's second color video board for the IBMInternational Busiuness Machines PCIBM PC family, capable of a maximum resolution of 640x350 pixels in 16 simultaneous colors of a total of 64 possible colors. clone with up to 800x600 and full 6845 emulation. native VGAVideo Graphics Array(Video Graphics Array) The video adapter introduced with the IBMInternational Busiuness Machines PS/2IBM PS/2, any model series of computers. : all registers 00-18h are r/w, but 00h-07h are write-locked if bit7 in 11h is set. ET4000 : same as VGAVideo Graphics Array(Video Graphics Array) The video adapter introduced with the IBMInternational Busiuness Machines PS/2IBM PS/2, any model series of computers., but with additional r/w registers 32h-37h, protected by 'key' except 33h, 35h (see 3BFh for details). 35h is protected by bit7 in 11h. The 'key' must be issued at least after each power on or synchronous reset. SeeAlso: #P0708,#P0710,#P0655,#P0656,#P0710 Bitfields for mono video adapter mode control register: Bit(s) Description (Table P0655) 7 not used by MDA(Monochrome Display Adapter) A text-only video adapter introduced together with the original IBMInternational Busiuness Machines PCIBM PC. See also CGAColor Graphics Adapter, HGC., page number on HGC(Hercules Graphics Card) A monochrome video adapter capable of 720x352 monochrome graphics. The HGC was the first non-IBM video adapter for the IBMInternational Busiuness Machines PCIBM PC. See also CGAColor Graphics Adapter, MDA. 6 not used 6 R-O (mono ET4000 only) report status of bit 1 (enable 2nd page) of Hercules compatibility register (PORTIBM PC Portable (uses same BIOS as XT) 03BFh) 5 enable blink (0 = intense background, 1 = blink) 4 not used 3 video enable 2 not used 1 (MDA(Monochrome Display Adapter) A text-only video adapter introduced together with the original IBMInternational Busiuness Machines PCIBM PC. See also CGAColor Graphics Adapter, HGC.) not used (HGC(Hercules Graphics Card) A monochrome video adapter capable of 720x352 monochrome graphics. The HGC was the first non-IBM video adapter for the IBMInternational Busiuness Machines PCIBM PC. See also CGAColor Graphics Adapter, MDA.) graphics enable the 6845 has to be reprogrammed completely, if this bit is changed, otherwise the TTL-monitor may be damaged by wrong sync impulses! 0 high resolution mode (always set on MDA(Monochrome Display Adapter) A text-only video adapter introduced together with the original IBMInternational Busiuness Machines PCIBM PC. See also CGAColor Graphics Adapter, HGC.) ---mono ET4000 only, W-O --- 7-0 =A0h: second part of 'key', see Hercules compatibility register (PORTIBM PC Portable (uses same BIOS as XT) 03BFh) for details Note: this port might be completely or partially readable on very few MDA(Monochrome Display Adapter) A text-only video adapter introduced together with the original IBMInternational Busiuness Machines PCIBM PC. See also CGAColor Graphics Adapter, HGC., HGC(Hercules Graphics Card) A monochrome video adapter capable of 720x352 monochrome graphics. The HGC was the first non-IBM video adapter for the IBMInternational Busiuness Machines PCIBM PC. See also CGAColor Graphics Adapter, MDA. clones or emulations (e.g. Genoa SuperEGA), but not with the majority of original and clone chips. It cannot be found on native mono EGAEnhanced Graphics Adapter(Enhanced Graphics Adapter) IBMInternational Busiuness Machines's second color video board for the IBMInternational Busiuness Machines PCIBM PC family, capable of a maximum resolution of 640x350 pixels in 16 simultaneous colors of a total of 64 possible colors., mono VGAVideo Graphics Array(Video Graphics Array) The video adapter introduced with the IBMInternational Busiuness Machines PS/2IBM PS/2, any model series of computers., but on most clones, where it is usually R/W. SeeAlso: #P0654,#P0656 Bitfields for mono video adapter CRT status register: Bit(s) Description (Table P0656) 7 HGC(Hercules Graphics Card) A monochrome video adapter capable of 720x352 monochrome graphics. The HGC was the first non-IBM video adapter for the IBMInternational Busiuness Machines PCIBM PC. See also CGAColor Graphics Adapter, MDA.: vertical sync pulse in progress 6-4 adapter identification (MSD says) if bit 7 changes within 8000h reads then =000 adapter is Hercules or compatible =001 adapter is Hercules+ =101 adapter is Hercules InColor else: adapter is unknown 6-4 =111 on MDA(Monochrome Display Adapter) A text-only video adapter introduced together with the original IBMInternational Busiuness Machines PCIBM PC. See also CGAColor Graphics Adapter, HGC. and some HGC(Hercules Graphics Card) A monochrome video adapter capable of 720x352 monochrome graphics. The HGC was the first non-IBM video adapter for the IBMInternational Busiuness Machines PCIBM PC. See also CGAColor Graphics Adapter, MDA. clones 5-4 (mono EGAEnhanced Graphics Adapter(Enhanced Graphics Adapter) IBMInternational Busiuness Machines's second color video board for the IBMInternational Busiuness Machines PCIBM PC family, capable of a maximum resolution of 640x350 pixels in 16 simultaneous colors of a total of 64 possible colors., mono ET4000) diagnose video display feedback select from color plane enable 3 (MDA(Monochrome Display Adapter) A text-only video adapter introduced together with the original IBMInternational Busiuness Machines PCIBM PC. See also CGAColor Graphics Adapter, HGC.,HGC(Hercules Graphics Card) A monochrome video adapter capable of 720x352 monochrome graphics. The HGC was the first non-IBM video adapter for the IBMInternational Busiuness Machines PCIBM PC. See also CGAColor Graphics Adapter, MDA.) pixel stream (0=currently black, 1=currently white) (mono EGAEnhanced Graphics Adapter(Enhanced Graphics Adapter) IBMInternational Busiuness Machines's second color video board for the IBMInternational Busiuness Machines PCIBM PC family, capable of a maximum resolution of 640x350 pixels in 16 simultaneous colors of a total of 64 possible colors., mono VGAVideo Graphics Array(Video Graphics Array) The video adapter introduced with the IBMInternational Busiuness Machines PS/2IBM PS/2, any model series of computers.) vertical retrace in progress 2-1 (MDA(Monochrome Display Adapter) A text-only video adapter introduced together with the original IBMInternational Busiuness Machines PCIBM PC. See also CGAColor Graphics Adapter, HGC.) reserved 2 (HGC(Hercules Graphics Card) A monochrome video adapter capable of 720x352 monochrome graphics. The HGC was the first non-IBM video adapter for the IBMInternational Busiuness Machines PCIBM PC. See also CGAColor Graphics Adapter, MDA., mono EGAEnhanced Graphics Adapter(Enhanced Graphics Adapter) IBMInternational Busiuness Machines's second color video board for the IBMInternational Busiuness Machines PCIBM PC family, capable of a maximum resolution of 640x350 pixels in 16 simultaneous colors of a total of 64 possible colors.) lightpen flipflop set (mono ET4000) reserved (0) 1 (HGC(Hercules Graphics Card) A monochrome video adapter capable of 720x352 monochrome graphics. The HGC was the first non-IBM video adapter for the IBMInternational Busiuness Machines PCIBM PC. See also CGAColor Graphics Adapter, MDA.) lightpen input stream (if set, current value to get from PORTIBM PC Portable (uses same BIOS as XT) 03B5h registers 10h-11h) (mono ET4000) reserved (0) 0 horizontal drive enabled SeeAlso: #P0654,#P0655 Bitfields for EGAEnhanced Graphics Adapter(Enhanced Graphics Adapter) IBMInternational Busiuness Machines's second color video board for the IBMInternational Busiuness Machines PCIBM PC family, capable of a maximum resolution of 640x350 pixels in 16 simultaneous colors of a total of 64 possible colors.,VGAVideo Graphics Array(Video Graphics Array) The video adapter introduced with the IBMInternational Busiuness Machines PS/2IBM PS/2, any model series of computers. mode control register: Bit(s) Description (Table P0657) 7 0=CRTC reset and stop, 1=resume reset 6 0=word-mode, 1=byte-mode (VGAVideo Graphics Array(Video Graphics Array) The video adapter introduced with the IBMInternational Busiuness Machines PS/2IBM PS/2, any model series of computers.: see 14h, bit6) 5 0=14bit, 1=16bit address wrap 4 (native VGAVideo Graphics Array(Video Graphics Array) The video adapter introduced with the IBMInternational Busiuness Machines PS/2IBM PS/2, any model series of computers. only) reserved (0) 4 (EGAEnhanced Graphics Adapter(Enhanced Graphics Adapter) IBMInternational Busiuness Machines's second color video board for the IBMInternational Busiuness Machines PCIBM PC family, capable of a maximum resolution of 640x350 pixels in 16 simultaneous colors of a total of 64 possible colors. and most VGAVideo Graphics Array(Video Graphics Array) The video adapter introduced with the IBMInternational Busiuness Machines PS/2IBM PS/2, any model series of computers. clones) output control 0: video driver active 1: video driver not active 3 linear address counter clock (0 = standard, 1 = clock/2) (VGAVideo Graphics Array(Video Graphics Array) The video adapter introduced with the IBMInternational Busiuness Machines PS/2IBM PS/2, any model series of computers.: see register 14h, bit 5) 2 horizontal retrace clock (0 = standard, 1 = clock/2) 1 row scan counter 0: address bit 14 = scan bit 1 1: address bit 14 not altered 0 6845 compatibility mode 0: address bit 13 = scan bit 0 (as with 6845) 1: address bit 13 not altered SeeAlso: #P0654