PCjr MEMORY OPTIONS
	      TECHNICAL REFERENCE MATERIAL
	      ____________________________







	I.  INTRODUCTION


       II.  AUTOMATIC INSTALLATION PROGRAM


      III.  EXPANDED MEMORY DEVICE DRIVER


       IV.  MEMORY DISK DEVICE DRIVER


	V.  CREATE/EDIT THE DOS CONFIGURATION FILE





I.  Introduction



The PCjr Memory Options diskette contains four files in support of
expanded PCjr memory:


      1. INSTALL.COM -	Automatic Installation Program

      2. CONFIG.SYS  -	Default DOS Configuration File

      3. PCJRMEM.COM -	Expanded Memory Device Driver

      4. RAMDISK.COM -	Memory Disk Device Driver


In order for your expanded PCjr memory to be fully utilized by DOS and your
applications, you must install the Expanded Memory device driver on your backup
DOS diskette(s) (ie, the DOS diskette you use to start your PCjr.)  You can
also install a Memory Disk device driver on your expanded PCjr.  This will
give your PCjr the capability to have a "logical" second diskette drive that
is part of your PCjr memory rather than being a real diskette drive.  To
install these device drivers, you can run the automatic installation program
(see Section II) or you can create/edit the DOS configuration file yourself
(see Section V.)



II.  Automatic Installation Program



The automatic installation program (INSTALL) is the simplest way to install the
Expanded Memory device driver and your Memory Disk device driver onto your DOS
backup diskette(s).  The "Update to Disk Operating System 2.10 for the IBM PCjr
Memory Options" describes how to operate this program.

In configuring for expanded memory, the files CONFIG.SYS and PCJRMEM.COM are
placed onto your backup DOS diskette.  To verify this you could list the
directory to see the two new files.

The next time you start the PCjr from this DOS backup diskette, the expanded
PCjr memory will be available to DOS and all applications which are loaded by
DOS.

If you have other DOS backup diskettes, you can install the Expanded Memory
device driver on each of them by following the instructions from INSTALL.


If you have application diskettes that contain DOS for automatic start-up,
you can also install the Expanded Memory device driver onto them provided
there is enough room (2048 bytes of available space is necessary) and
provided the application can run with expanded memory.	For applications that
contain DOS, follow these steps:

	1. Install DOS onto the application diskette by following the
	   instructions that come with your application.  You can of course
	   use that diskette "as is" without taking advantage of expanded
	   PCjr memory.

	   All applications which run on the 128k PCjr will still run the same
	   with expanded memory even if the Expanded Memory device driver is
	   not installed.

	   Some applications may not take advantage of the expanded PCjr memory,
	   so it is not absolutely essential to install the Expanded Memory
	   device driver for their use.  Also some applications have been
	   written to operate only in the original 128k PCjr environment.  In
	   these cases, you should maintain a DOS backup diskette without
	   installing the Expanded Memory device driver.


	2. Verify that the application can run with expanded memory by following
	   these steps:

		* - Insert the "PCjr Memory Options" diskette in the diskette
		    drive and switch your PCjr on or do a System Reset
		    (Ctrl-Alt -Del.)
		* - Insert your application diskette in the drive and activate
		    it by specific command (follow application instructions or
		    type AUTOEXEC.)

	3. If the application runs and takes advantage of the expanded memory,
	   then you could install the Expanded Memory device driver to the
	   application diskette.  The application diskette must already have
	   DOS on it before you run the INSTALL program.





If your DOS or Application/DOS diskette already has a DOS configuration file
(CONFIG.SYS), then the automatic installation program will append the
appropriate device drivers to the end of the current CONFIG.SYS file.  If
you run INSTALL and these new device drivers are already present in CONFIG.SYS,
then the new configuration (eg, memory disk size) will replace the old.

The automatic installation program installs the Expanded Memory device driver
to allow for the maximum amount of user memory to be available for applications
while providing full PCjr text and normal PCjr graphic capabilities.
Applications which use enhanced PCjr graphics (such as 320x200 16 color,
640x200 4 color, or multiple graphic pages) require the Expanded Memory device
driver to be specified with a special parameter (see Section III.)




III.  Expanded Memory Device Driver



The Expanded Memory device driver allows DOS and applications loaded by DOS to
fully utilize the expanded PCjr memory.  Without installing the Expanded
Memory device driver, memory on your PCjr is configured as follows:



	     0K *************************
		*			*
		*	DOS 2.1 	*
		*			*
		*		    24K *
	    24K *************************
		*			*
		*	DOS		*
		*			*
		*	AVAILABLE	*
		*			*
		*	MEMORY		*
		*			*
		*	FOR		*
		*			*
		*	LOADING 	*
		*			*
		*	APPLICATIONS	*
		*			*
		*		    88K *
	   112K *************************
		*   PCjr VIDEO BUFFER	*
		*		    16K *
	   128K *************************
		*			*
		*			*
		*			*
		*	EXPANDED	*
		*			*
		*	PCjr		*
		*			*
		*	MEMORY		*
		*			*
		*			*
		*			*
		*			*
		*			*
		*			*
		*			*
		*			*
		*			*
		*			*
		*************************





As the diagram shows, the expanded PCjr memory is present but is not available
to DOS for loading applications larger than 88K.  This is because the default
PCjr video buffer is located at the top 16K of the PCjr's first 128k bytes of
memory.  The expanded memory is still usable and applications could address the
expanded memory directly but must skip over the video buffer or move the video
buffer themselves.  Your BASIC programs could BLOAD directly into the expanded
memory leaving the video buffer alone.

In order for DOS and applications loaded by DOS to take advantage of the
expanded PCjr memory, the Expanded Memory device driver must be installed on
the DOS backup diskette.  See Section II or V.	The name of the Expanded Memory
device driver is PCJRMEM.COM and it can be specified in any one of three
different ways corresponding to one of three different modes of operation.



The Expanded Memory device driver modes of operation:


							PCjr	Video
					User		Video	Modes
Mode	       Specify			Memory		Memory	Allowed
----	       -------			------		------	-------


Normal	       DEVICE=PCJRMEM.COM	Maximum for	16k	All text modes
					Normal			160x200 16 color
					Applications		320x200 4 color
								640x200 2 color
								1 graphic page





Enhanced       DEVICE=PCJRMEM.COM /E	Maximum for	32k	All text modes
					Enhanced		160x200 16 color
					Applications		320x200 4 color
								640x200 2 color
								320x200 16 color
								640x200 4 color
								1 32k page
								2 16k pages



Compatible     DEVICE=PCJRMEM.COM /C	Applications	128k	All text modes
					Use Only The		160x200 16 color
					Expanded		320x200 4 color
					Memory			640x200 2 color
								320x200 16 color
								640x200 4 color
								4 32k pages
								8 16k pages


Normal Mode:
___________




Specifying DEVICE=PCJRMEM.COM without a parameter will configure the device
driver in "normal mode".  In this mode, the device driver will move the PCjr
video buffer to be resident inside of DOS and allow the rest of the PCjr
memory to be contiguous and available for applications loaded by DOS.  The
following illustrates the PCjr memory when configured in "normal mode":




	     0K *************************
		*			*
		*	DOS 2.1 	*
		*			*
		* +--------------------+*
		* ! PCjr VIDEO BUFFER  !*
		* !		    16K!*
		* +--------------------+*
		*			*
		*		    52K *
	    52K *************************
		*			*
		*			*
		*			*
		*	DOS		*
		*			*
		*			*
		*	AVAILABLE	*
		*			*
		*			*
		*	MEMORY		*
		*			*
		*			*
		*	FOR		*
		*			*
		*			*
		*	LOADING 	*
		*			*
		*			*
		*	APPLICATIONS	*
		*			*
		*			*
		*			*
		*			*
		*			*
		*			*
		*			*
		*			*
		*************************









This mode allows for the maximum amount of memory to be available for
applications while providing a 16k PCjr video buffer.  This mode provides
for full PCjr text capabilities and IBM PC compatible graphic capabilities
(i.e., 160x200 16 color, 320x200 4 color, and 640x200 2 color.)  This mode
does not support the PCjr enhanced graphic modes of 320x200 16 color or
640x200 4 color , since they require a 32k PCjr video buffer.

The size of DOS including the Expanded Memory device driver is variable
dependent upon what other device drivers and DOS buffers are also included in
the DOS configuration file.  Also, the order of the device drivers could be
significant, since the Expanded Memory device driver will position the PCjr
video buffer at a 16k byte boundary.  So if you do specify other device
drivers, make sure you order them to your best advantage.



Enhanced Mode:
_____________




Specifying DEVICE=PCJRMEM.COM /E will configure the device driver for enhanced
graphic capability.  In this mode, the PCjr video buffer will be moved inside
of DOS yet allows all PCjr text and graphic modes.  The rest of the PCjr memory
will be contiguous and available for applications loaded by DOS.  The following
illustrates the PCjr memory when configured in "Enhanced Mode":






	     0K *************************
		*			*
		*	DOS 2.1 	*
		*			*
		* +--------------------+*
		* !		       !*
		* ! PCjr VIDEO BUFFER  !*
		* !		       !*
		* !		    32K!*
		* +--------------------+*
		*			*
		*		    84K *
	    84K *************************
		*			*
		*			*
		*			*
		*	DOS		*
		*			*
		*			*
		*	AVAILABLE	*
		*			*
		*			*
		*	MEMORY		*
		*			*
		*			*
		*	FOR		*
		*			*
		*			*
		*	LOADING 	*
		*			*
		*			*
		*	APPLICATIONS	*
		*			*
		*			*
		*			*
		*			*
		*			*
		*************************





This mode allows for the greatest amount of memory to be available for
applications while providing 32k for PCjr video usage.	This mode provides
for full PCjr text capabilities and full PCjr graphics capabilities
(including the enhanced PCjr modes of 320x200 16 color and 640x200 4 color.)
Since 32k is available for PCjr video, either a single enhanced graphic page
(32k) or two normal graphic pages (16k each) are available for applications.

The size of DOS including the Expanded Memory device driver is variable
dependent upon what other device drivers and DOS buffers are also included in
the DOS configuration file.  Also, the order of the device drivers could be
significant, since the PCjr Memory Expansion device driver will position the
PCjr video buffer at a 32k byte boundary.  So if you do specify other device
drivers, make sure you order them to your best advantage.



Compatible Mode:
_______________



Specifying DEVICE=PCJRMEM.COM /C will configure the device driver for a fully
compatible PCjr operation.  In this mode, all of the PCjr's first 128k bytes of
memory will be reserved for DOS and the PCjr video usage.  Only the expanded
PCjr memory will be available for applications loaded by DOS.  The following
illustrates the PCjr memory when configured in "Compatible Mode":




	     0K *************************
		*			*
		*	DOS 2.1 	*
		*			*
		*			*
		* +--------------------+*
		* !		       !*
		* !		       !*
		* !	RESERVED       !*
		* !		       !*
		* !	FOR	       !*
		* !		       !*
		* !	PCjr	       !*
		* !		       !*
		* !	VIDEO	       !*
		* !		       !*
		* !	USAGE	       !*
		* !		       !*
		* !		       !*
		* !		    96K!*
		* +--------------------+*
		*		   132K *
	   132K *************************
		*			*
		*			*
		*	DOS		*
		*			*
		*	AVAILABLE	*
		*			*
		*	MEMORY		*
		*			*
		*	FOR		*
		*			*
		*	LOADING 	*
		*			*
		*	APPLICATIONS	*
		*			*
		*			*
		*			*
		*			*
		*			*
		*************************



This mode provides for full PCjr text and graphic capabilities including
multiple graphic pages and compatible direct video buffer addressing.  This
mode does not allow the maximum amount of memory to be available for most
applications which only need text or normal graphic modes; thus, it may not
be the most desirable.	This mode does guarantee that applications will
execute in the expanded PCjr memory.




IV. Memory Disk Device Driver




The Memory Disk device driver when installed will transform part of your PCjr
memory into a "logical" disk.  Thus, you have another disk in which to save and
load programs and files.  Programs and files that are stored in the memory disk
are treated just like programs and files on a real diskette except that they are
saved and loaded much faster and (unfortunately) if you power off your computer
they will be lost.  Thus, if you want to save information from your "memory"
disk, make sure you COPY the files/programs to a real diskette before you power
off your computer or perform a system reset (Ctrl/Alt/Del).

The Memory Disk is referenced by the diskette drive identification of "C:".
Most of the DOS diskette commands will apply to the memory disk such as DIR,
COPY, ERASE, CHKDSK, etc.; and all applications will access programs and files
from the memory disk merely by prefixing the filename with the drive ID of
"C:".  Of course since the disk is in memory, you effectively have a single
diskette always loaded that does not need to be FORMATed.  It could be thought
of as a "hard" file in memory.


To install the Memory Disk device driver, you can use the INSTALL program (see
Section II) or you can create/edit the DOS configuration file (CONFIG.SYS) on
your DOS backup diskette (see Section V.)

The Memory Disk device driver is a file named RAMDISK.COM.

You can specify the amount of memory you want to allocate for your memory
disk in K (1024) byte increments as a parameter after the device driver
filename.  The number must be in the range of 10 to 512 or the memory disk
will be allocated with the default size of 60K bytes.  If you specify a number
larger than the available memory on your PCjr, then you will receive a memory
disk of only the amount available less approximately 64k.


For example:



	DEVICE=RAMDISK.COM /128



	will create a memory disk with the capacity of 128k
	bytes or 131,072 characters.

	Part of the memory disk (approximately 5k) is used for
	directory space, so all 128k bytes are not available
	for programs and files.





For example:



	DEVICE=RAMDISK.COM /88



	will create a memory disk with the capacity of 88k bytes.








If you install the Memory Disk device driver, then the memory you allocate
for the disk is not available for your application programs.  Therefore,
make sure you leave enough memory for your applications to be loaded and run
efficiently.  The amount you specify must leave enough memory for DOS, the
device driver itself (approximately 1k), and your application programs.



The following illustrates the PCjr memory configuration for a Memory Disk
of 100k and the Expanded Memory device driver operating in "normal" mode:



	     0K *************************
		*			*
		*	DOS 2.1 	*
		*			*
		* +--------------------+*
		* ! PCjr VIDEO BUFFER  !*
		* !		    16K!*
		* +--------------------+*
		*			*
		* +--------------------+*
		* !		       !*
		* !		       !*
		* !		       !*
		* !		       !*
		* !		       !*
		* !	 MEMORY        !*
		* !		       !*
		* !	 DISK	       !*
		* !		       !*
		* !		       !*
		* !		       !*
		* !		       !*
		* !		       !*
		* !		       !*
		* !		       !*
		* !		   100K!*
		* +--------------------+*
		*		   152K *
	   152K *************************
		*			*
		*	DOS		*
		*			*
		*			*
		*	AVAILABLE	*
		*			*
		*			*
		*	MEMORY		*
		*			*
		*			*
		*	FOR		*
		*			*
		*			*
		*	LOADING 	*
		*			*
		*			*
		*	APPLICATIONS	*
		*			*
		*			*
		*************************





If you try to install the Memory Disk device driver without specifying the
Expanded Memory device driver, only 88k bytes of memory is available because
of DOS and the PCjr video buffer.  You MUST install the Expanded Memory device
driver to take advantage of any expanded memory.  Also you MUST (I repeat MUST)
specify the Expanded Memory device driver ahead of the Memory Disk device
driver in your CONFIG.SYS file.





V.  Create/Edit The DOS Configuration File


To install any device driver to your DOS backup diskette(s) you must create the
DOS configuration file named CONFIG.SYS and specify the device driver filename
following the characters "DEVICE=".  To do this you can use any file editor
such as EDLIN or Personal Editor.  You can also create it from the keyboard
using the DOS command "COPY CON: CONFIG.SYS".  For more information on these
topics refer to your DOS reference manual.

The filename for the Expanded Memory device driver is PCJRMEM.COM.
The filename for the Memory Disk device driver is RAMDISK.COM.

An example in creating the DOS configuration file is as follows:



STEP	ACTION

  1	Insert your DOS backup diskette with the write protect tab removed
	into the drive and close the door.

  2	Enter:

	   COPY CON: CONFIG.SYS

  3	Enter:

	   DEVICE=PCJRMEM.COM
	   DEVICE=RAMDISK.COM /80

  4	Press Fn then 6 and Enter


  5	The message "1 FILE(S) COPIED" and the DOS prompt ">"
	should appear when CONFIG.SYS creation has completed.


  6	Insert the PCjr Memory Options diskette into the drive,
	and close the door.

  7	Enter:

	   COPY PCJRMEM.COM B:

	The message appears:

	   Insert diskette for drive B: and strike any key when ready


  8	Insert your DOS backup diskette into the drive, close the door, and
	press any key.




  9	Insert the PCjr Memory Options diskette into the drive,
	and close the door.


  10	Enter:

	   COPY RAMDISK.COM B:

	The message appears:

	   Insert diskette for drive B: and strike any key when ready


  11	Insert your backup DOS diskette into the drive, close the door, and
	press any key.



The Expanded Memory device driver and the Memory Diskette Drive device
driver are now installed on your DOS backup diskette.

The next time you start from this DOS diskette the expanded PCjr memory
will be available to DOS and all applications which are loaded by DOS;
and you will have an 80k byte disk located in your PCjr memory.