




 PLUSTOOL FOR DOSPLUS 3.5
 Author Paul Martin


 PLUSTOOL provides the programmer with a powerful tool for modifying the initialization defaults on the DOSPLUS 3.5 Operating System.  Several functions are provided:

(1)  NEW BOOT SECTOR -- The boot sector in DOSPLUS 3.5, as furnished, is not compatible with the Model 4-P Computer in Model III mode; since it will not cause the computer to find and load the ROM image file, MODELA/III.   PLUSTOOL will write a new boot sector onto your DOSPLUS disk to correct this fault.  The new boot is identical to the original boot in all other respects.

(2)  UPPER CASE -- DOSPLUS 3.5 normally boots up with the lower case set.  This is frequently an annoyance, and can be changed to upper case using  PLUSTOOL.  At any time that you wish, this can be reversed to lower case again.

(3)  BASIC FILES -- The default number of files (buffers) that are enabled when initializing BASIC, can be altered at will using  PLUSTOOL; you may install any default value from 0 to 15.  This can be changed at any time.


UTILIZING  PLUSTOOL

 PLUSTOOL is a high speed, machine language program which is wholly resident in RAM after loading.  Thus it may be used in computers with only one disk drive, if needed.  All of the modifications that  PLUSTOOL provides may be performed upon any existing DOSPLUS 3.5 System disk, without regard for user data and files already on that disk.   PLUSTOOL will not alter or damage existing files.

Any and all modifications made to a DOSPLUS 3.5 disk by the PLUSTOOL utility will be self-propagating to all future backup copies made from that disk.  The new boot is carried over to all backups, and need not be added to them.

Make a BACKUP copy of  PLUSTOOL before proceeding, and save the original in a safe place.   PLUSTOOL is provided on an open disk, without media protection.  You may make as many copies of it as you wish.

Insert your BACKUP copy of  PLUSTOOL in drive #0, and press RESET.  Answer the date and time prompts as usual.  At the READY prompt, type  PLUSTOOL and press <ENTER>.

The screen will display the program title and copyright notice, and a menu consisting of four choices:

<B>..Install new bootstrap sector
<U>..Upper/lower case default
<D>..Disk I/O buffers default
<X>..Exit to DOSPLUS

Each of the three functions is a separate procedure, and can be used at any time and in any sequence, whether or not you will be using any of the others.  The fourth selection allows you to exit and return to DOSPLUS.


INSTALL NEW BOOTSTRAP SECTOR

This function installs the new bootstrap sector on the disk.  Since this is an improvement over the original boot, there would be no reason to reverse the operation and restore the original boot, therefore no facility is provided for reversing this function.

A disk that already contains the new boot sector may be recognized when booted, by the fact that in the upper righthand corner of the billboard display the version number will read "3.5P" instead of the original "3.50".

When you select function <B> you will be prompted to mount the disk to be modified onto Drive #0, and press <ENTER>.  As soon as you have done this, the message "Modifying the DOSPLUS disk.." will display briefly, and then you will be prompted to "Press any key for menu..".  The entire process takes only a second or so.  Upon return to the menu, you may select another function, or insert another disk to be modified, or you may press <X> to return to DOSPLUS if no further modifications are needed.

A technical note: The DOSPLUS boot sector, located in Sector 00H of Cylinder 00H, contains two other bytes of information used by the computer, in addition to the boot sector itself.  Relative byte 01H contains a disk type identifier; usually, but not always FEH.  Relative byte 02H indicates which cylinder contains the directory file, DIR/SYS.  This is usually, but not always, cylinder 14H.  Whenever you use the <B> function of  PLUSTOOL, it first notes the contents of these two bytes, and copies them to the new boot image, before installing it on your disk.  This is a completely automatic process; and is not something the operator needs to be aware of.  It is mentioned here only as a point of interest for the machine language programmer.


UPPER/LOWER CASE DEFAULT

As furnished, DOSPLUS 3.5 is configured such that upon boot-up, it is in the lower case mode.  That is, you must depress the <SHIFT> key to obtain an upper case letter.  For some applications this is ideal, but in others it is more of a nuisance.   PLUSTOOL allows you to change this at any time, and as often as you wish.

Select function <U>.  You will be advised to mount the disk to be modified onto Drive #0.  When you press <ENTER> you will be offered the options of <0> for lower case, or <1> for upper case default initialization.  Press the selection of your choice.  The screen will advise you that it is modifying the disk, and in about one second you will be prompted to "Press any key for menu..".  The process is now completed.  As before, you may go on to other functions if you wish, or to another disk, or you may return to DOSPLUS by selecting <X>.


A technical note:  For the machine language programmer interested in the technicalities of this function, the byte controlling the default upper/lower case characteristic is located at relative byte 03H of sector 02H, cylinder 00H.  If it's value is 00H it will boot in lower case mode; a value of 01H causes the boot to come up in upper case mode.


DISK I/O BUFFERS DEFAULT

Whenever you call upon BASIC in the DOSPLUS system, it automatically enables a predetermined maximum number of file buffers, for use in disk I/O programming; you may not exceed this number with your BASIC program.

It is important to have this number high enough to permit operation of any software you plan to run in BASIC, and yet it should not be excessively high, since this would waste memory space.  A common number for this purpose is three.  It is a very rare piece of software that will have more than three I/O buffers open at any one time.  The vast majority of programs uses only one buffer.

DOSPLUS allows this number to be anywhere between zero and fifteen, inclusive.  Instructions for changing this number by the use of the DISKDUMP utility on DOSPLUS, are furnished with the software.  A much simpler method of changing the number is to use the <D> function of  PLUSTOOL.

After selecting the <D> function, you will be prompted to mount the disk to be modified onto Drive #0, and to press <ENTER>. The computer will then prompt you to type in the number of default disk files desired, from 00 to 15.  You must type in two digits; the computer will not accept a single digit for this response.  That is, if you wish to install the number six, for example, you must type 06.  The computer will not accept a number larger than 15.  The number 00 is permitted if that is what you wish.  Press <ENTER> once again, and you will see a brief "howgozit" display advising you that the disk is being modified, followed almost immediately by a prompt to "Press any key for menu..".  At this point, the task is completed, you may go to another function, or another disk, or you may return to DOSPLUS.

A technical note:  The interested programmer may wish to know that the byte controlling this function is located at relative byte 0AH of relative sector 12H of the file BASIC/CMD.  Since the location of this file may differ from one disk to another, the cylinder number is not pre-known.   PLUSTOOL first locates the file, then loads its twelfth (hex) sector to perform the modification, and then rewrites that sector back to its original position on the disk.  And since the file BASIC/CMD is a protected system file, special accessing techniques are employed to circumvent this protection.


MEDIA SPECIFICATIONS

 PLUSTOOL is a machine language command file containing 1523 (decimal) bytes; START7000H, END75F2H, TRA7000H, corresponding to decimal values of START28672, END30194, TRA28672.

 PLUSTOOL is a copyrighted software product, and may not be copied or distributed by the purchaser, except for his own use. It will operate on any TRS-80 Model III computer, and on any TRS-80 Model 4 or 4-P computer in Model III mode.  One or more disk drives are required, and the ROM and DOSPLUS environments must be present since many routines in these areas are utilized.


PLUSTOOL was written and submitted to MSS By Paul Martin of Naples, Fla. We wish to thank Paul for this valuable utility.
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