trs-80 Tips and Tricks - DOS Tips and Tricks

For those of you who have used the basic version of SUPERZAP from NEWDOS 2.1 to peek at the directory of the MODEL-III TRSDOS, you may have noticed that the password encode for a null (blank) password is EF5C rather than the old familiar 9642 from the MODEL-I. This is caused by Radio Shack using a slightly different algorithm to encode the passwords (they changed two bytes in the code), but the system works in much the same way. This article will explain three ways to get around the password system if you have a need to do so. The first two will require the above mentioned SUPERZAP, which is all we have until someone comes up with a version tailored to the MODEL-III's double density disk structure. the third method doesn't require any utility program at all and can be used by anyone.

• ZAPPING THE DIRECTORY - Use SUPERZAP to select track 1B, sector 4. This will bring you to the first sector of the directory. Then, use the ";" key to page through the directory until you find the programs you want. The first four bytes of the second line of each directory entry are the update and access password encodes respectively and, on an unprotected file, they will be EF5C EF5C. To remove the passwords on a protected file, just zap EF5C into the entry in place of whatever you find there. just like the MODEL-I. Don't waste any time looking for the SYS Files. They aren't listed by name in the directory and don't have passwords anyway.
• DISABLING PASSWORD CHECKING - You can dispense with passwords altogether if you want to. Use SUPERZAP to bring up track 1A, sector 2. Then use the MOD function of SUPERZAP to change relative byte DE from 28 to 18. Press ENTER and type Y to write the modified sector back to the diskette. From now on, all passwords will be ignored when accessing files if this diskette is used in drive #0.
• THE MASTER PASSWORD - If you don't have SUPERZAP or don't want to make any modifications to TRSDOS, you can access any file regardless of protection by using a master password to over-ride all other passwords. One such password is "NYXB". This acts as a master key to unlock any file and can be used if you have a diskette with a master password other than "PASSWORD".

Functions to Read, Test, and Change bits:

DEF FNReadBit   (Address,Bit) = INT(PEEK(Address)/2^Bit)-2 * INT(PEEK(Address)/2^(Bit+1))
DEF FNResetBit  (Address,Bit) = PEEK(Address) - FNReadBit(Address,Bit) * 2^Bit
DEF FNSetBit    (Address,Bit) = PEEK(Address) + (1-FNReadBit(Address,Bit)) * 2^Bit
DEF FNToggleBit (Address,Bit) = FNResetBit(Address,Bit) + FNSetBit(Address,Bit) - peek(Address)

109 -- Bit 1==>  Type-Ahead
		   Set = Enabled
		 Reset = Disabled

116 -- Bit 5==>  Caps
		   Set = Upper Only
		 Reset = Upper/Lower

121 -- Bit 7==> Spooler
		   Set = Despooling
		 Reset = Paused

124 -- Bit 4==>  Break Key
		   Set = Disabled
		 Reset = Enabled

127 -- Bit 4==>  Clock Display
		   Set = Display On
		 Reset = Display Off

127 -- Bit 6==>  Cursor Control
		   Set = Non-Blinking
		 Reset = Blinking

For example to turn the clock display on from BASIC use the statement:
POKE 127,FNSetBit(127,4).

Print string of number without a leading space:
Call with A set to the number.

DEF FNST$(A)=RIGHT$(STR$(A),LEN(STR$(A))-1)

Function to display the current DOS version:

DEF FNVersion$="TRSDOS Version " + LEFT$(HEX$(PEEK(133)),1)+"." + RIGHT$(HEX$(PEEK(133)),1) + "."+HEX$(PEEK(59))

Function to display the current date in 'Day, Mon ##, 19##' format:

DEF FNDay$=MID$("SunMonTueWedThuFriSat",(((PEEK(55)AND 14)/2)-1)*3+1,3)+", "+MID$("JanFebMarAprMayJunJulAugSepOctNovDec",(PEEK(53)-1)*3+1,3)+" "+RIGHT$(" "+FNST$(PEEK(52))+", 19"+FNST$(PEEK(51))

Print appropriate article in front of a word:
Call with A$ = to the word that you want the article in front of.

DEF FNARTICLE$(A$)="A"+LEFT$("n",INSTR("AEIOUaeiou",LEFT$(A$,1)))+" "+A$

Display a menu number in reverse video:
Call with A = to menu number to display.

DEF FNNUM$(A)="{"+CHR$(16)+FNST$(A)+CHR$(17)"} "

Condense the TIME or DATE strings to 4 bytes:
Call with A$ = to TIME$ or DATE$.

DEF FNTIMEDATE$(A$)=MKS$(VAL(LEFT$(A$,2)+MID$(A$,4,2)+RIGHT$(A$,2)))

Expand time or date string as condense above:
Call with A$ = Condensed string -- B$ = seperator, '/' or ':'.

DEF FNEXPAND$(A$,B$)=STRING$(6-LEN(FNST$(CVS(A$))),48) +
LEFT$(FNST$(CVS(A$)),(LEN(FNST$(CVS(A$)))-4))+B$ +
LEFT$(RIGHT$(FNST$(CVS(A$)),4),2)+B$ +
RIGHT$(FNST$(CVS(A$)),2)

Pad string on right or left to a specific length:
Call with A$ = String -- A = maximum length to output

DEF FNRSPC$(A$,A)=LEFT$(A$+SPACE$(A),A)
DEF FNLSPC$(A$,A)=RIGHT$(SPACE$(A)+A$,A)

These remarks are an attempt to explain how you may create CMD files, the only purpose for which is to have more disk space available for data files or whatever.

Using cmdfile you merely call for SYS6 or SYS7, depending where the routine you wish is located, and then give the overlay number when requested. these numbers may be found by reading a download of sys1 with the extended debugger. to make it easier i am listing them below:

I'll leave it to you to figure out to which sys file each of these belongs, reminding you that it is obligatorily SYS6 or SYS7. Let's assume you wish to create a CMD file of the copy command. Merely enter the number 32 when you are requested. it is not necessary to change addresses or transfer addresses, since you will be using the command file exactly as you would have used the library routine. Save the file with a different name since if you call 'copy' the parsing routine will load the routine from SYS6 and not your COPY/CMD file. In any case, you would only wish to create these cmd files to replace SYS6 and SYS7, reducing the overhead on your disk. This is especially useful for users with only disk drive. Since these routines, when changed into cmd files, will occupy a full gran of 5 sectors (6 on double density), it is clear that if you create too many such files, you will have defeated the purpose of eliminating the SYS6 and SYS7 files! as for names of the corresponding files, i should opt for names similar enough to the library commands to avoid confusion with yourself, ccopy for copy, ddir for dir, etc.

Finally, for those who wish to better understand the principle employed with the library, i will explain how a routine is parsed and then loaded and run from its sys file. When you enter a command, it is parsed by SYS1, and a table with the names of all the LIB routines, each followed by the index no. shown above. Following that number is an 80 or a c0, which tells the system to look for the in SYS6 or SYS7. within the SYS6 or SYS7 file a search is made for the index number. this number is followed by the starting address of the routine once loaded and the relative sector number and relative byte where the routine is located within the sys file. The routine is loaded and executed.

I hope these remarks will assist any interested users in better understanding both my idea of creating command files to save space, and of the library routines themselves.

TRSDOS 6.x is an advanced version of the LDOS operating system designed for use on all-RAM computers using the Z80 processor. TRSDOS 6.x supports a variety of disk types, although only a few are documented in the official Tandy documentation. Drive types supported include:

• 5" mini-floppy in single- and double-density, single- and double-sided, with cylinder counts of up to 96.
• 8" floppy in single- and double-density, single- and double-sided and 77 cylinders.
• Hard (or "rigid") drives of various sizes, cylinder and head counts.

All that is required to take advantage of these disk types is the hardware itself and the proper "driver" to control it. Full support for all 5" drive types is included with the basic TRSDOS system, but only 40-track, single sided operation is documented.

To use a double-sided drive under TRSDOS, all that is necessary (apart from the drive itself) is to format the diskette for two sides. In non-Tandy versions of LDOS 6.x, the FORMAT utility will prompt the user for the number of sides to format, however Tandy asked that this prompt be bypassed due to the fact that they do not sell a double-sided drive for the model 4. You can still format for two sides, though. All that is necessary is to specify "SIDES=2" in the parameter section of your command line.

Thus: FORMAT :1 (cyl=80,sides=2) will format drive 1 for 80 tracks and 2 sides. FORMAT will ask for disk name and master password.

If you wish to then use this double-sided diskette as your "boot" diskette, you *must* be sure that SYS0/SYS begins with the first sector of a cylinder. The only way to guarantee this is to back it up to the blank diskette *first*. To do this, use the command: BACKUP SYS0/SYS:0 :1 (S)

Follow that with: BACKUP SYS/SYS:0 :1 (NEW)

To defeat backup protection on TRSDOS 6.x disks:

10 OPEN "R",1,"BOOT/SYS.LSIDOS:0"
20 GET 1, 3: POKE VARPTR (#1) + 198,0
30 PUT 1,3: CLOSE: END

To read a Model 4 TRSDOS 6.0 or a Model III LDOS disk directly on NEWDOS/80 V.2, use this PDRIVE setting:

TI=A, TD=E, TC=40, SPT=18, TSR=3, GPL=6, DSL=12, DGA=2

You can execute DOS commands from BASIC by using the RUN library command of TRSDOS.

Example: SYSTEM"RUN COMM *CL" will run the COMM/CMD program.

Note: SYSTEM"COMM *CL" will result in an error message - you MUST use the RUN command.

If you hate the commands that the Shack set up for TRSDOS 6.x, you can change them!!! Using your file editor, read in SYS1/SYS.LSIDOS. The DOS commands are contained within the file. You can change the bytes of the commands to get a new command. If the command falls short of 6 characters, fill the rest of the space with 20H (32 decimal). Example: Change DIR to D, REMOVE to K.

To use LDOS or TRSDOS 6.x to write-protect disks in drive 1:

From LDOS READY type: SYSTEM (DRIVE=1, WP=Y) (or WP=N to unprotect).

From TRSDOS READY type: WP (DRIVE=1) (or WP to unprotect).

Ah, the glory of rebelling against the untrue statements in the TRSDOS 6.2 manual. The manual says that you should not call any DOS routines without using the SVC's (LD A,x and RST 28H). Why not escape this waste of source and use a CALL xxxxH instruction? It is also faster because DOS won't need to look up the SVC's in the table. The Shack would scream if us programmers were making TRSDOS 6.2 run faster than a snail...but is it worth the pain of the scream to save the ENDLESS pain of RST 28H instructions? Also, now that we have the addresses to all the SVC's, let's get the disassemblers into action and disassemble this DOS 6.2 thing and disseminate the good new undocumented addresses. One catch is that this is not guaranteed to work on DOSes other than 6.20. DO NOT USE TRSDOS 6.21 has it has a bug that erases parts of files on the disk! It just totally ignores the granule allocation table! Well, I think I've said enough of this crap, so let's get to business. The rules for calling the DOS routines are the same as for the SVC's, except instead of LD A,x and RST 28H you CALL xxxxH. The registers must be the same on entry. The exit conditions remain the same. It is still advisable to PUSH AF when calling DOS routines because the routines may internally use AF. For an explanation of the routines (DOS names have been used in this file), see your copy of the Model 4 TRSDOS manual.

SVC'S #107-#127 are free for you to use. SVC #107 is found in location 01D6H. Each one after that is found two bytes later. You can use the following formula to calculate exact locations (under DOS 6.20):

LOC=0100H+SVC*2

Where SVC is the number of the SVC you wish to program. You CAN program OVER the DOS SVC's, but should you use this practice, use the @IPL SVC (#000, address 1BF2H) to exit your program. If you don't wish to reboot, store the original SVC table in a buffer as follows:

LD HL,0100H
LD DE,BUFFER
LD BC,0100H
LDIR

The SVC table is 256 bytes long and is ALWAYS found on a page boundary (even multiples of 100 hex). Should the SVC table get moved, you can get its starting address by using this code...

LD A,101
RST 28H
LD A,(IY+26)
LD H,A
LD L,0
; NOW HL HAS THE ADDRESS - MSB IS IN H, LSB ALWAYS ZERO.

NOTE: If the SVC table got moved, the addresses provided above would be wrong.

To Enable:

PATCH *0:0 (ADD=4EA9,FIND=C3,CHG=CA)

To Disable:

PATCH *0:0 (ADD=4EA9,FIND=CA,CHG=C3)

One of the things I quickly discovered as I began working with my new Model 4P was that there was going to be a need to move data back and forth between my old NEWDOS disks and LDOS6 disks. The following procedure is very straightforward, and will work without hassle for those important data files.

Note: The following procedure requires at least two drives!

NEWDOS80 V2 to LDOS v6.2

• Boot under LDOS6.2.
• Format a disk SSSD, 35 tracks. You MUST use single side, single density and 35 tracks, regardless of the type of drive you are actually using!
• Boot NEWDOS80 V2. (Note, if you are a 4P owner, and are having problems booting NEWDOS, see the info file on this topic)
• Set the PDRIVE for the drive where the LDOS disk resides to TI=A,TD=A,TC=35,SPT=10,GPL=2,DDSL=17,DDGA=2.
• Use the normal NEWDOS Copy command to copy the file from your NEWDOS80 disk to the LDOS disk.
• Reboot the system using LDOS6.2.
• Use the RESET command or TSK/CMD if you have several copied files) to CLOSE each of the copied files. NEWDOS is not familiar with the open/closed status, and will leave each file open when copying it over to LDOS.

That's all there is to the job in that direction. Going the other way is just as easy.

LDOS v6.2 to NEWDOS80 V2

Perform the steps above in the following order:

• Boot in 6.2
• Format as noted above. Then, copy files as desired to the newly formatted disk while still in LDOS.
• Boot NEWDOS.
• Set PDRIVE as noted above.
• Use normal NEWDOS copy command to move files from the LDOS disk to the NEWDOS disk.

Provided you have a Model 4 (and not a 4P) you may also find that it is fairly fast to use Multidos for this sort of thing.

At last we have some questions to answer on LDOS!! The first one comes from a Newdos 80 user, who wants to know "How to configure LDOS, and what all the /DVR and /FLT files do", and the second from a TRSDOS 6.x user who wants to access the system status flags from within a BASIC program.

Configuring LDOS:

The first thing that should be done to configure LDOS for the system you use is to list the options that your system needs- e.g. Double Density, Printer Driver, etc. The easiest way to do this is to list your current Newdos configuration, or if you don't use Newdos, your hardware and its requirements.

Using an existing Newdos system configuration list, I have listed the Newdos configuration options below and their LDOS counterparts. Items marked + cannot be SYSGENed under LDOS. Items marked * can be done if a driver or filter is written.

• Having chosen the required configuration alternatives, install them into LDOS by issuing the necessary commands.
• When you are certain that all your chosen functions are operational, type SYSTEM (SYSGEN) to get LDOS to create a configuration file and write it to drive 0. Please note that EVERYTHING in high memory (including SYSRESed /SYS files) will be included in this file, so ensure that you have sufficient room on the floppy to save the file.
• Once the configuration file is written, power down and then back up again to get a cold start of the system. I have found that some configurations will appear OK if a warm start test is done, but not if a cold start test is done - particularly if the disk is a SOLED double density boot disk.
• A typical configuration for a system with 3 drives is -
  PDUBL - for double density.
  SET *KI KI (TYPE,JKL) - type-ahead, JKL, etc.
  SYSTEM (BLINK=143) - blinking block cursor.
  SYSTEM (DRIVE=3,DISABLE) - drives 0, 1 & 2 only.
  SYSTEM (DRIVE=2,STEP=1) - drive 2 is 12 m/s step.
  SYSTEM (TYPE) - activate type-ahead.
  FILTER *KI MINIDOS - activate MiniDOS.
  FILTER *PR PR (ADDLF) - add linefeeds to printer.
  ZSHELL - Misosys command processor.
  
• Type SYSTEM (SYSGEN)

If you are in Model I DOS BASIC and forgot to set Memory Size. Do the following, and it will re-set the memory size. While it will say LEVEL II BASIC it will still be DOS BASIC.

SYSTEM
*? /177

MultiDOS has the ability, for those with double sided disk drives, to format each side of the disk as a separate side, each side being accessible without ejecting or flipping the disk!

To do this, MultiDOS will use the drive number alone (i.e., 1) for Side 0 of that drive and the drive number with an apostrophe (i.e., 1') for Side 1

If you are fortunate enough to have a double sided drive, you can do this in one easy step:

Type CONFIG :1 (SIDES=2) and press ENTER.

You can verify that it took by typing in CONFIG and pressing ENTER. If you did it right, the line for Drive 1 will now say "2 side(s)".

If you want to format the second side, simply run FORMAT but type 1' instead of 1. Same for every DOS command which takes a drivespec.