Category : Display Utilities
Archive   : HGCIBM.ZIP
Filename : HGCIBM.DOC

HGCIBM.COM Version 2.02
Copyright (C) Athena Digital, Gary Batson 1986, 1987
2351 College Station Road, Suite 567, Athens, Ga. 30605
404/354-4522

This Manual Dated June 1, 1987








































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TABLE OF CONTENTS

HGCIBM.COM

Acknowledgments .............................................. 3
Trademarks ................................................... 3
Using HGCIBM.COM ............................................. 3
Precautions .................................................. 3
Installation ................................................. 4
Using the Command Line ....................................... 5
HGCTEST program .............................................. 5
Sales and Distribution Policies .............................. 6
User Comments ................................................ 6
History ...................................................... 6
Future ....................................................... 7
Changes and Corrections ...................................... 7
Technicalities ............................................... 8

Athena Digital Video BIOS

Purpose ...................................................... 9
Features ..................................................... 9
Control Program .............................................. 11
Sales and Distribution Policies .............................. 11
Software Author Note ......................................... 12
Extended Functions ........................................... 13
Library Versions ............................................. 19
QBDEMOC program .............................................. 19

This program is distributed as Shareware. All rights are reserved
except for distribution of the program, its documentation, and
any DEMO materials IN ITS ENTIRETY and un-modified. You may test
and use this program for 30 days, after which you must register
it, destroy it, or pass in along to a friend. If you would like
to keep HGCIBM, see the pricing within. This DOES NOT APPLY to
those who contributed to HGCIBM Version 1.11. Those individuals
are welcome to this upgrade without further remuneration. Please
accept it with my THANKS!!

Athena Digital's program and emulation algorithms were first
Copyrighted June 10, 1986. It is now the basis for the existence
of Athena Digital and represents months of effort and a large
personal investment. Any information presented in this document
or available in the associated programs is and shall remain the
Copyrighted Property of Athena Digital. Any attempt to use this
information to create a competitive product, whether the product
is distributed "free" or otherwise is in violation of copyright
laws.

Athena Digital
2351 College Station Road, Suite 567, Athens, Ga. 30605





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DISCLAIMER

Athena Digital makes every effort to ensure that this
documentation is accurate. However, because we are constantly
striving to improve our products, we are unable to guarantee the
accuracy of the contents of this document after the date of
publication and we disclaim liability for any changes, errors or
omissions. We have also made every effort to warn you of possible
damage to your equipment from careless use of other applications
with ours. If you do somehow damage your display or anything
else, Athena Digital ASSUMES ABSOLUTELY NO RESPONSIBILITY FOR IT.
If it will make you more confident, no such claims have ever
been made against us .. but we have to protect ourselves.


ACKNOWLEDGMENTS

Athena Digital would like to thank IBM for creating the Personal
Computer and Hercules Computer Technology for making PC graphics
as pleasurable as PC TTL text.


TRADEMARKS MENTIONED

Hercules and RamFont are trademarks of Hercules Computer
Technology.

IBM is a trademark of International Business Machines.

Microsoft, QuickBASIC, CodeView and MS-DOS are trademarks of
Microsoft Corporation.

Athena Digital Video BIOS is a trademark of Athena Digital.


USING HGCIBM.COM

The purpose of this program is to provide owners of Hercules
Graphics Cards a means to run software written for the IBM Color
Graphics Adapter, and to introduce a commercial version of the
BIOS called Athena Digital Video BIOS which offers added
functionality.


PRECAUTIONS - MONOCHROME DISPLAY DAMAGE !!!

This program will not damage your display, but certain
application software certainly can. Programs which attempt to by-
pass the BIOS (Basic Input/Output System) to set the CRT
operating parameters will cause severe problems. Fortunately
since most software operates in standard modes, most software
developers permit BIOS to set up the controller for them even if
they later write to screen ram directly.
(cont'd)



3









HGCIBM will intercept the BIOS calls for all standard modes and
program the controller correctly. Writing directly to screen ram
is permitted and the emulator will still work properly. When
trying an un-tested (with HGCIBM) program for the first time,
watch your display carefully for signs of gross distortion or
shrinking when the program sets graphics mode. IF THIS OCCURS,
RE-BOOT OR TURN OFF YOUR COMPUTER IMMEDIATELY. The display should
return to normal quickly when you re-boot.

HGCIBM INSTALLATION

To install the emulator, you must tell it what mode to start in,
and a little information about your hardware. There are three
"modes" of operation for HGCIBM as follows:

The /E[mulate] mode enables the emulator to respond to BIOS calls
to set standard CGA modes and provides maximum compatibility with
programs expecting to use the Color Graphics Adapter, but
displays the information on your Hercules adapter. When the
emulator is in this mode, the text buffer is at segment B800 and
the equipment flag is set to indicate that a CGA card is present.
Alas, you can't fool all the programs all the time. Some of them
read the equipment flag and then try to manipulate the crt
controller directly in order to provide faster screen output.
Naturally they try to do this at the CGA port addresses (which
don't exist) and will hang the system (This problem is overcome
with Athena Digital Video BIOS). A re-boot will cure the problem
and you should then remember to either un-install the emulator
before running these programs or simply place it in /M(ono) mode
or /C[GA] mode (if you have a physical CGA) as described below.

The /M[ono] mode effectively disables HGCIBM without un-installing
it. The monochrome card is selected and Video BIOS control
returns to the computer's ROM (Read Only Memory).

The /C[ga] mode also disables HGCIBM and returns control to ROM
except the physical Color Graphics Adapter is selected (if it
exists).

There are also 3 installation switches available to warn HGCIBM
about special hardware. During initialization, the program tries
to determine if a Color Graphics Adapter is present. If it is,
the program will not install unless you assure it that the Color
Graphics Adapter in your system is compatible with Hercules
Graphics cards. If yours is or you have a Leading Edge computer,
then you should use the following switches:

The /H[ercules Compatible] switch instructs HGCIBM to install and
allow the emulation mode even though a Color Graphics Adapter is
present. You may use this switch on installation if you have a
Hercules compatible CGA card in your system. If a CGA card is
present, HGCIBM will abort installation unless the /H switch is
used.
(cont'd)



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Also note that some software will output to the CGA registers
(3D4, 3D5, 3D8, etc.) to adjust video parameters. This can wreak
havoc on the real CGA adapter while in Emulation mode. If the CGA
is not physically present, this output causes no problems and is
ignored by Hercules adapters.

The /L[eading Edge] switch instructs HGCIBM to install if the
Leading Edge Model D is connected to a TTL display.

The /U[n-install] switch instructs the emulator to reset all
vectors and remove itself from memory, freeing the space for
other programs. You may un-install the emulator provided that
other programs have not altered vectors 8h and 10h, but memory
may become segmented if you have loaded another resident program
after HGCIBM. The system will be left in the same condition it
was in before the installation. (i.e. monochrome display).

USING THE COMMAND LINE

Simply type the command HGCIBM with a mode switch to install or
change to that mode. If you have special hardware, ADD the
hardware switch to the mode switch on the same command line as
shown in the following examples:

HGCIBM /M - installs in (or changes to) MONO mode (emulation
disabled)
HGCIBM /C - installs in (or changes to) CGA mode (emulation
disabled)
HGCIBM /E - installs in (or changes to) Emulation mode.
HGCIBM /U - un-installs the emulator
HGCIBM /M/H - informs HGCIBM that a Hercules compatible CGA is
physically present.
HGCIBM /M/L - informs HGCIBM that you have a Leading Edge
Model D computer.

These commands may be issued from a batch file if desired.
Hardware switches (/H or /L) are needed only on installation.

To change modes after installation, just enter the command as
above. HGCIBM always checks to see if it is already installed and
will process the command correctly.

HGCTEST PROGRAM

This program is provided for you to test the operation of HGCIBM
with your computer configuration. Before running HGCTEST, Load
the emulator with the /E[mulate] switch. HGCTEST.BAS runs under
BASICA. Just enter BASICA HGCTEST to run it (assuming BASICA is
on the default disk drive with HGCTEST.BAS). The program is a
simple graphics demo and is self explanatory. If you have a basic
compiler, the demo program can be compiled to test the compiler.





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SALES AND DISTRIBUTION POLICIES - HGCIBM.COM

There is no limitation on distribution of HGCIBM.COM as long as
no remuneration is accepted in connection with it's distribution,
and as long as it is distributed un-modified, in it's entirety
(including any DEMO materials), and BY ITSELF. IT MUST NOT BE
DISTRIBUTED WITH your own application program or hardware, but it
is OK to mention that your software/hardware will/wont run with
it and our name and telephone number (so he can obtain a copy to
run your program). You are permitted a 30 day trial period to
decide whether or not you wish to keep HGCIBM or purchase Athena
BIOS after which you must either register it with Athena Digital,
destroy it, or pass it along to someone else. The registration
fee for HGCIBM.COM is $10.00 in check or money order (see
REGISTER file in this package).

OEMS and Dealers are encouraged to support Athena BIOS with their
products. HGCIBM is an extremely limited version of Athena
Digital's software. Those interested should contact Athena
Digital for details.

USER COMMENTS

Let us know what you think. Any criticism is better than none and
will help to steer us along a path which is in the majority's
best interest. Your suggestions need not be limited to graphics.
Any comment regarding Athena Digital programs or documentation is
welcome.

Thank you for your support.

HISTORY

In June of 1986, Athena Digital released a simple "Freeware"
emulator for Hercules cards which supported only the 200 by 640
Color Graphics Card mode (HGCIBM.COM Version 1.11). To our
knowledge, this was the first such program publicly released. At
first glance there would appear to be no physical way to
effectively display CGA graphics on a ttl card. It not only could
be done, but done in such a way that resulting display quality is
actually better than the real CGA though it is in shades of one
color. Support came in from users as far as Israel and eventually
from CGA software developers. Though it represented no serious
income, This support inspired Athena Digital to create HGCIBM.COM
Version 2.00 which offers emulation support of all of the CGA
modes and to start the development of Athena's own Video BIOS to
support not only emulation, but to provide an upgradable and
expandable Video BIOS which enhances any display system.








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FUTURE

Version 2.02 provides only a SUBSET of the Athena Digital support
functions. It is a functional emulator only, and does not offer
support for Microsoft Mouse, Extended Video BIOS calls, RamFont,
or EGA. Due to restrictions imposed by the "resident" utility
implementation, the commercial release of Athena's BIOS
(ATHENA.SYS Version 3.00) is in the form of an MS-DOS Device
Driver. Installed in this way, the program becomes as much a part
of the operating system as is the ROM Video BIOS, except that it
can be easily upgraded and enhanced. Future enhancements will be
limited to Athena BIOS, thus obsoleting HGCIBM.COM except as a
simple emulator. If bugs are found in HGCIBM, they will be
corrected. For more information about the commercial products,
read the section called Athena Digital Video BIOS in this
document.

HGCIBM CHANGE AND CORRECTION NOTES

o Version 1.11 would sometimes crash with programs that
intercepted the timer interrupt while in Graphics, and
then changed to text.

o If interrupts were redirected, Version 1 could not find
itself for a mode change and would install a second
copy. Now it can find and control itself unless it is
by-passed altogether.

o Version 2.00 (beta test version) would not install on a
Leading Edge due to differences in the way the Leading
Edge video buffers are implemented. This was corrected
with the /L[eading Edge] switch.

o Version 2.01 failed to detect the EGA and would treat
it as a CGA. Now HGCIBM will abort installation as it
is supposed to.

ENHANCEMENTS
o Version 2.02 contains a SUBSET of Athena Digital's own
Video BIOS and will support a wider range of
compatibles as well as the AT. This also provided a
means for improved screen behavior in color text mode,
and faster screen operations if BIOS is used.

o All standard video modes are now supported. The 320 x
200 mode supports two intensities(colors). Color 1 and
color 2 will appear identical, where color 3 will be
high intensity. Forty column text is supported but will
be displayed on the left half of the screen only at the
same resolution as eighty column text. All four pages
of 80 column text (or 8 pages of 40 column text) are
available on CERTAIN Hercules cards. Some cards will
display only one page (Athena Video BIOS displays all
pages on all Hercules Adapters and clones).



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TECHNICALITIES

HGCIBM installs itself between two BIOS (Basic Input/Output
System) interrupts. The two interrupts used in this way are hex
10 (BIOS video) and hex 8 (timer). The later is used only while
in emulation mode. HGCIBM will fail to function properly if it is
not given control during the above interrupts. Other software
using interrupt 8 will be called on a priority basis, preempting
HGCIBM if necessary. HGCIBM version 2.02 no longer passes
interrupt 10h (while in emulation mode) since it was learned that
compatible ROM BIOS was not always entirely compatible. If you
have other software using interrupt 10h, try loading it after
HGCIBM. You can still control HGCIBM after the interrupt is
changed but you will not be allowed to un-install it. HGCIBM need
be loaded only once each time the computer is started since it
attaches itself to BIOS and stays in memory until re-boot or it
is commanded to detach. The memory usage has increased to about
5k now due to bypassing of ROM video BIOS in emulation mode, but
does provide much improved color text emulation and should be
compatible with a wider variety of machines.




































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Athena Video BIOS Version 3.00
Copyright (C) Athena Digital 1986,1987

Preliminary Specifications - Subject to change without notice.

PURPOSE

For some unknown reason, hardware and software vendors have not
seen fit to establish adequate specifications and graphics
support for the widely used Hercules Graphics standard. The most
peculiar aspect of this is the fact that the Hercules standard
was the third available for the IBM personal computer and the
first which offered truly high graphics resolution as well as the
first to support graphics on the ttl monochrome display. Today,
this standard is almost universally accepted as the display
adapter of choice for ttl monochrome PC systems and its display
quality is yet challenged only by the EGA standard which
unfortunately requires an expensive color monitor to exploit it's
capabilities.

Athena Digital will attempt to remedy the problem by making it as
simple as possible for vendors to exploit the capabilities of the
Hercules card, CGA, EGA and others. Athena BIOS now fully
supports the Hercules monochrome card and/or Color Graphics Card,
the EGA (and eventually others) with fast support for standard
modes, CGA emulation, and several new modes.

One of the primary enhancements provided by ATHENA BIOS is
Emulation of the Color Graphics Adapter on the Hercules Graphics
Card. This allows Hercules owners to run the majority of graphics
programs which do not already support the Hercules adapter. The
list includes programs like BASICA, QuickBASIC, CodeView and the
majority of all others.

This eliminates the need for a Color monitor and graphics card in
many cases with obvious price advantages.

Athena also provides BIOS support for the higher resolution
Hercules 350 vertical by 720 horizontal modes, and a new 350
vertical by 360 mode with three intensities and 4 logical pixel
colors. ALL of the Standard BIOS call support for these new modes
including character generation, scrolling, and adapter switching
which greatly simplifies direct support of Hercules high
resolution modes by software vendors.

ATHENA FEATURES

o Available in Programmer's Libraries for linking with high or
low level languages.

o Supports 6 new Hercules only modes, which are as
readily available to applications developers as are the
standard modes.



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o Provides extended equipment, system capability information
for applications.

o Supports Color Graphics Adapter Programs on the Hercules
Graphics Card.

o Fully compatible with Microsoft Mouse or Microsoft Mouse
software look-alikes.

o Includes a "Buss Terminator" which eliminates ALMOST all
of the application software incompatibility with Emulation
modes. This allows Microsoft's CodeView and QuickBasic
editors to function normally in Emulation mode.

o BIOS Character generation and scrolling in Emulation Modes
is accomplished without ghosting and no appreciable loss in
speed (it is usually faster than the CGA through ROM BIOS).

o All 4 pages of 80 column CGA text (or 8 pages of 40 column
text) are available on ALL Hercules cards or compatibles.

o Fully supports Hercules - Enhanced Graphics (color monitor)
combinations.

o Fully Compatible with the new Hercules Plus card in 4K
RamFont or Rom text mode.

o Supports new "Context Switching" between adapters and
certain modes.

o Supports faster video operation in ALL modes than Standard
ROM BIOS.

o Simple replacement for "buggy compatible" BIOS.

o Installs as a device driver for MS-DOS version 2.00 or later

o Adds PC-AT BIOS print string functions to the PC

Once installed, Athena BIOS replaces the standard ROM video BIOS.
Software installation is a matter of copying ATHENA.SYS to your
boot disk, and inserting a one line command in your MS-DOS
config.sys file. This MUST be the FIRST "DEVICE =" command in the
file following the MOUSE and has the following basic form:

DEVICE = MOUSE.SYS
DEVICE = ATHENA.SYS

Athena BIOS is compatible with a variety of MS-DOS
computers, including the PC, PC-XT, PC-AT, and Leading Edge, and
most any other hardware compatible. Our aim is to work with as
many different computers and display adapters as possible.




10









Version 3.00 Video Bios does not replace EGA BIOS, but is
compatible with it and controls it. If a non-ega adapter is
active, Athena BIOS controls the active adapter. While the EGA is
the active display, EGA BIOS controls the EGA adapter. Athena
BIOS supports the Hercules Graphics Card in FULL modes WITH the
EGA (if it is connected to a color display). The BIOS will
continue to add features supporting as many of the popular
adapters as possible and enhancing them wherever practical in
order to maintain compatibility for your programs.

CONTROLLING ATHENA BIOS AFTER INSTALLATION

With ATHENA.SYS, you are provided a utility which allows you
keyboard control over Athena's variety of modes. This utility
operates as any other external DOS command. Simply place it in
your program directory and use it with switches. If you forget
the switches, typing ATHENA will give you a help screen.

ATHENA /M[ono] - Places BIOS in MONO or EGA MONO mode
(emulation disabled)
ATHENA /C[ga] - Places BIOS in CGA or EGA Color mode
(emulation disabled)
ATHENA /E[mulate] - Places BIOS in CGA EMULATION mode.
ATHENA /S[tatus] - Gives a report of Athena's status.
ATHENA /Q[uiet] - ADDING this switch to others to suppress
messages.
ATHENA /D[isable] - Disables the BIOS and returns control to
ROM
ATHENA /R[eset] - Resets and enables the BIOS.

These commands may be issued from a batch file if desired.

SALES AND DISTRIBUTION POLICIES - ATHENA.SYS

For the purchase price of $34.95, you will receive the program on
a 5.25" IBM format diskette with documentation and Buss
Terminator, and be notified of upgrades at low cost as they
become available.

Dealers, OEMS, and those desiring Site Licenses are welcome and
encouraged to contact Athena Digital about liberal discounts.















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SOFTWARE AUTHORS

Using Athena Video BIOS Libraries, you can easily upgrade your
application to support Hercules Adapters. There are several
options available to you with the library:

o You can link Athena Digital Video BIOS with your
application. This allows your program to use all Athena
functions whether the Athena device driver is present
or not.

o You can link with the interface module only. This
allows you to detect and and use Athena BIOS if the
Device Driver is present.

o You can link a PARTIAL BIOS with your application. This
allows you to use the CGA Emulation modes whether the
Device Driver is present or not, but defeats the usage
of Hercules Extended modes.

See the QBDEMO program included for many more details.

SUPPORTED HARDWARE

o IBM PC /XT /AT and most hardware compatibles which have an
expansion buss. (Expansion buss not necessary for
Libraries or for systems which will not need CGA Emulation).

o Microsoft Mouse (device drivers) or software compatibles
which provide Microsoft's defined function calls.

o The following Video hardware combinations have been tested
to date:

Hercules Graphics Adapter, all versions including Plus. (MGA)
IBM Monochrome Text Adapter. (MTA)
IBM Color Graphics Adapter .. Hercules Color Card. (CGA)
IBM Enhanced Graphics Adapter (EGA)
Monochrome EGA with CGA
Color EGA or CGA with MTA or MGA.
















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Athena Digital Video BIOS FUNCTION CALLS

This information is provided for technical users, and
presumes familiarity with Standard BIOS function calls. Presented
here is a subset of available services. A complete listing is
available in the Athena Video BIOS Programmers Reference Manual,
provided with each Programmer's Library.

THIS DOCUMENT CONTAINS PRELIMINARY INFORMATION ABOUT ATHENA VIDEO
BIOS CONTEXT CALLS. THE PURPOSE OF THIS IS TO SHOW THE INTENT OF
THE CALLS. FOR PERMANENT AND ACCURATE INFORMATION, RELY ON THE
PROGRAMMER'S REFERENCE DATA PROVIDED WITH LIBRARY PACKAGES.
; ****
(AH)=B0h SetContext - (AL) contains context value

These functions first save the current BIOS variables in the
current Context Buffer, then change the current VideoState
"emulation active" flag according to the table below and take one
of three actions depending on the condition of the target
screen's Context save buffer. There are 3 save buffers in the
initial Athena BIOS release:

o Hercules / Monochrome / Mono EGA adapter page at 0B000h
o Hercules adapter page at 0B800h
o Color Graphics Adapter / Color EGA Adapter at page 0B800h

Each save buffer has room for:

o The current crt_context
o The current crt_mode
o The current crt_columns
o The current crt_len
o The current crt_start
o The current cursor_posn[8]
o The current cursor_mode
o The current active_page
o The current addr_6845
o The current crt_mode_set
o The current crt_palette
o The current rows
















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Call B0h (cont'd)

The three possible actions through call B0h are:

o If register AL bit 7 = 1 (or'd with 80h), the target
screen Context buffer is initialized and the screen
is cleared.

Otherwise, the screen is not cleared and the Context
buffer is treated as follows:

o If the target context's save buffer has not been
overwritten since it was saved, it is restored intact.

o If the target context's save buffer has been
overwritten, it is initialized to default values of the
Target Context before restoration.

Context switches do not "blink" the screen unless it is necessary
to re-program the 6845 controller to make the switch.

This is a powerful function. It enables programmers to switch
rapidly back and forth between graphics and text, or between
adapters without having to concern themselves about re-
initializing or restoring the screen(s). It also permits rapid
switching between 40 or 80 column graphics text modes without
loss of screen data, allowing mixed use of the provided (or user
provided) character fonts in Hercules Graphics modes. When
switching between 40 and 80 column text, the Context buffer is
initialized, so it is necessary to locate the cursor wherever you
want it in the new text map.

Context switches also affect the way Athena interprets calls to
the standard BIOS function 0 as shown below. These calls cannot
be used to overide the hardware setup determined by Athens during
initialization. Calls for invalid context switches are ignored
and the call returns with the carry flag set:



















14









Athena BIOS function call B0h (continued):
CONTEXT VALUES AND EFFECTS ON CGA EMULATION FLAG
;
TARGET MODE EMULATION TARGET SCREEN

Standard Modes (Contexts)

(AL)=0 deactivated CGA/EGA 40x25 alpha
(AL)=1 deactivated CGA/EGA 40x25 alpha
(AL)=2 deactivated CGA/EGA 80x25 alpha
(AL)=3 deactivated CGA/EGA 80x25 alpha
(AL)=4 deactivated CGA/EGA 200x320 graph
(AL)=5 deactivated CGA/EGA 200x320 graph
(AL)=6 deactivated CGA/EGA 200x640 graph
(AL)=7 deactivated MONO/EGA 80x25 alpha
(AL)=13 deactivated EGA 320x200 graph
(AL)=14 deactivated EGA 640x200 graph
(AL)=15 deactivated EGA 640x350 graph
(AL)=16 deactivated EGA 640x350 graph


Call B0h (cont'd)
Hercules only modes

CGA Emulation Contexts: (correspond to Standard modes 0 - 6)
(AL)=20
. activated HERC page at B800*
.
(AL)=26

Hercules Logical Text Context 27:
(supports 8 pages of 80 column text on ALL Hercules Cards)
(AL)=27 deactivated HERC 80x25 alpha

Hercules Graphics Contexts 28,29,30,31:
(AL)=28 deactivated HERC 350x720 at B000
(AL)=29 deactivated HERC 350x720 at B800
(AL)=30 deactivated HERC 350x360 at B000*
(AL)=31 deactivated HERC 350x360 at B800*

*modes 24,25, 30 and 31 support low and high intensity















15









Certain Context changes are not possible without erasure of the
contents of a previously buffered Context. To gain an
understanding of which context switches can be performed without
erasing another, study the above table. Context switches between
adapters never cause erasure. Context switches between differing
Hercules pages are likewise retained, except for emulation text
Contexts 20,21,22,23, and Logical text Contexts 27.

Emulation and Logical text modes use BOTH Hercules pages, thereby
erasing any previously saved Hercules Context .

; ****
(AH)=D0h SetAdapter - (AL) contains new Context Value as
above. The new Context is set. This call supersedes
the original BIOS call 0, which re-maps Modes
to Contexts in order to effect transparent
Emulation.

This call will switch to, reset and clear the
target adapter, unless bit 7 is set, which inhibits
clearing of the target regen buffer. The Target CRT
Controller is re-initialized only if necessary.

; ****
(AH)=0 SetMode - al contains then IBM defined Mode value.
This call will not switch adapters unless the
equipment flag is changed prior to the call. The mode
value is re-mapped to an Athena Context value
depending on whether the BIOS is Emulating or not.
This call is designed to support applications which
are unaware of Athena BIOS. It's behavior is
identical to the standard BIOS.

Function 0 is superseded in Athena BIOS by function
D0, which accepts Context Values rather than Mode
values.

Function 0 supports the IBM defined flag bit 7
to inhibit regen buffer erasure.

















16









(AH)=BFh AthenaState - Return the current driver state.
OUTPUT:
(AL) = Current Context (as in call B0h)
(AH) = Character Columns on screen
(BH) = Current Active Display Page
(BL) = Reserved - destroyed
(DX) = Installed options, switch states
D0 = 1 if mono or Hercules card is installed
D1 = 1 if cga card is installed
D2 = 1 if an ega card is installed
D3 = 1 if Hercules modes/cga emulation are allowed
D4 = 1 if emulation modes are activated
D5 = reserved.
D6 = 1 if it is necessary to wait for
horizontal retrace before CGA text
screen updates. This bit is reset by
default when ATHENA initializes. If the
/W(ait) option switch is used on the
installation command line, this bit
will be set to cause ATHENA to wait for
retrace when updating CGA text. This
switch has no effect on Hercules or
Mono modes.
Application software should never
try to wait in Hercules modes since the
CGA registers may not even exist and
the Hercules standard does not require
it.
D7 - D15 = reserved.

(CX) = ATHENA/HGCIBM version number
(CH) has major version
(CL) has minor version

(BP) = Reserved - destroyed

(DI) = Reserved - destroyed




(continued)














17









Function BFh (continued)

(SI) = Extended Flags.
D0 = 1 if the EGA is connected to an Enhanced
Color Display.
D1 = 1 if the EGA is connected to a Monochrome
Display.
D2 = 1 if the system is in CGA Context 2 or 3,
AND the system is directed to wait for
CRT retrace to update the screen.
D3 = 1 if the EGA is currently the active
adapter.
D5 = 1 if the EGA is currently disabled.
(the system is in a Context which
requires ega ram to be disabled). While
disabled, function 12h will be ignored.
D6,D5 = Ega installed memory.
D7 = 1 if the EGA switches indicate it is the
Primary System Adapter.
D8 = 1 if there is a Microsoft Compatible
Mouse and it is currently emulating a
light pen.
D9 - D14 Reserved.
D15 = 1 if there is a Microsoft Compatible
Mouse and it reports -1 to function 0.

* set cx to -1 before calling function BFh, if the major version is
greater than or equal to 3, the response is from an Athena Video
BIOS device driver. If the major version is greater than or equal
to 23, the response is from an Athena Library BIOS. There will be
no Library response unless you linked with it. A response less
than 3 is from HGCIBM.COM, which will not occur if you are linked
with a library. If cx returns -1, there is no Athena BIOS.

HGCIBM.COM will not be upgraded past major version 2, and
behavior in general is somewhat different than from the BIOS. If
HGCIBM is detected, either ignore it or use only the emulation or
CGA modes. All future enhancements will be limited to Athena
Drivers or Libraries.

The above information is only a smattering of available services
and enhancements. Complete technical documentation is provided
with Programmer's Libraries and we don't recommend you try to
communicate with the BIOS without obtaining the technical
information.











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ATHENA LIBRARY VERSIONS

These are introduced in the accompanying QBDEMOC program. The
DEMO is subject to continuous updates and revisions as the
BIOS continues. It is entirely possible that new features and
capabilities have been added since this file was released. The
DEMO is a short first-hand introduction to Athena Device Drivers
and Athena Language Libraries for Programmers. If you find you
are seriously interested in Athena Digital Video BIOS, we will
send you the latest demo materials on request. There are 2 files
required to run the demo:

QBDEMOC.EXE ; QuickBasic library DEMO - BCOM20 program module
FEATURES.PRX ; DEMO text

o To run the demo, place these two files in your default
directory and type "QBDEMOC".

o If you have an older style Color Graphics Adapter which
"snows" when text is printed, then start the demo as
"QBDEMOC/W".

o It makes no difference whether HGCIBM is installed or not to
run the demo, since Athena Video BIOS is linked with the
demo and will be used in either case.

o DEMO Version 1.01 will now run on the EGA. If the EGA
is connected to a Monochrome Display, the Athena Logo will
display incorrectly. This appears to be a QuickBasic 2.00
bug but we have not yet heard from Microsoft about it so it
may just be our QuickBASIC programing. It definitely has
NOTHING to do with the BIOS.

In case the demo is missing, here are a scant few of the
highlights of Athena Video BIOS Libraries.

o Allows graphic (or text) programs written using standard
video BIOS for all except regen access to run unmodified on
a Hercules Graphics Card. It is only necessary to initialize
the BIOS on entry, and detach it on exit. An example of one
such program would be anything compiled under Microsoft's
QuickBasic and using QuickBasic's screen and graphics
functions such as QBDEMOC.EXE.

o Provides all of the functions that are described under
Athena Video BIOS above. Thus it offers immediate Hercules
support for existing applications, and a natural upward path
to extended Hercules support.








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o Cooperates with (or without) a resident Athena Device
Driver. If your Library is a later version, it automatically
coordinates a temporary "takeover" from the resident while
your program runs. Control returns to the resident when your
program exits. This assures that your program will always
use the latest BIOS available, whether its the one you
linked with or not.

o Libraries will probably be released for QuickBASIC, C, and
Macro Assembler by the time anyone could read this. Others
will be developed depending on customer interest. Write or
call us about your favorite programing language if you
would like to see an Athena library to link with it. The
library core is intrinsically compatible with any compiler
supporting external assembly language procedure calls and a
means of linking them with the compiled program code.

More details are available on request.






































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