Patch EDTASM+ To Disk

Patch EDTASM+ To Disk - To End Those Cassette Blues - By Roger Schrag

From: The Raimbow Magazine DIC 1982, Pag 29.

Radio Shack's EDTASM+ package is a powerful, well-written programming tool. But for people with disk drives, it is very agonizing to have to go back to using cassettes to store source code files. There are editor assemblers on the market that do support disk drives, but they are usually much more expensive, and sometimes require the Flex Operating System, or something else that not everyone owns.

What I have put together here is a series of patches that make EDT ASM+ use the disk drive instead of the tape recorder for mass storage. The finished product requires only 16K Extended Basic and one drive.

Patching EDTASM+ to use disks is relatively easy to do. The first thing is to move it into RAM so that we can alter bytes of code and thus alter its operation. The move can be accomplished by typing in U COOO 1000 27FF from Zbug. To save a copy of it on tape, enter P EDTASM 1000 37FE 1000. Since it was written entirely in position independent code, it can reside anywhere in memory, and function without modification.

The next step is to enter the source code shown in the listing. Assemble it onto tape directly after the copy of EDTASM+ you made from Zbug. You'll probably also want to save the source code for future use.

Now you are ready to load in the files you have saved on the tape. First, you will want to insert your disk cartridge so that the finished product can be saved on disk. Type CLOADM to load the RAM version of EDTASM+, but don't execute it yet. Next, load in the patches you keyed in by typing CLOADM again. Parts of EDTASM+ will now be overwritten with new code, and a block of additional subroutines will be added on.

You may save the finished program onto disk by typing in SAVEM "EDTASM+",&HE80, &H37FF, &HE80. Now whenever you want to use your editor assembler, just enter LOADM "EDTASM+": EXEC. with the disk version of EDTASM+, the L,W,A, and V commands will work differently than they used to. To load source code, simply press L and enter. The computer will ask for a filename. Type in a standard filename as you would in Basic. If you don't specify an extension, none will be assumed. The file will then be loaded. The W command works in the same way.

To assemble a program, type in A and any assembly switches you would like to use. Unless you choose the 1M or NO options, you will be asked for the filename. As the listing scrolls across the screen, the computer will stop from time to time to write a sector to the disk. If you press Break, you may have to wait a moment for the computer to close the file.

The V command will merely open a file and close it again. This verifies that a file is listed in the directory and that there are no problems with its structure.

On a 16K machine, you will have 1 .5K for your text buffer. A 32K machine will offer 17.5K. For those of you who have source code files on tape, you may transfer them to diskette with the Basic program I have included. EDTASM+ uses ASCII codes that Basic doesn't recognize.Therefore INPUT#-I can't be used to read the source code file from the cassette. A machine language routine is necessary.

Listing I:

09001 *************************
00002 * EDTASM+ HITS THE DISK *
00003 *************************
00004 *
00005 *BY ROGER SCHRAG
00006 * 10/15/82
00007 *
00008 *
00009 *HAKE SURE INTERRUPTS ARE ENABLED
00010 *SO THAT THE DISK DRIVE WILL
00911 *SHUT OFF PROPERLY
00012         ORG    $1516
00013         LBSR   INTRPT
00014 *
00015 *
00016 *CHANGE FILENAME HANDLING SYSTEM
00017 *TO ALLOW THE USER TO ENTER FULL
00018 *DISK FILE NAMES: FILENAME/EXT:D
00019         ORG    $15E0
00020         LBRA   FNAME
00021 *
09022 *
00023 *CHANGE REFERENCES TO DEVICE #-1
00024 *(TAPE) TO DEVICE #1 (DISK)
0002S         ORG    $1547
00026         LDB    #1
00027         ORG    $1574
90028         LDB    #1
00029         ORG    #15AD
00030         LDA    #1
00031         ORG    #15CD
00032         LDA    #1
00033 *
00034 *
00035 *HAKE SURE THE DISK FILE HAS BEEN
00036 *CLOSED WHEN ACCESS TO IT IS COMPLETE
00037         ORG    $1B52
00038         LBSR   CLOSE
00039 *
00040 *
00041 *AT THE RIGHT TIME, CALL A ROUTINE
00042 *TO OPEN THE DISK FILE, INSTEAD OF
00043 *A ROUTINE TO OPEN THE TAPE FILE
00044         ORG    #15BA   PATCHES INTO
00045         LDU    #ASSEM  "A" COMMAND
00046         ORG    $15BF   PATCHES INTO 
00047         LDU    #LOAD   "L" COMMAND 
00048         ORG    $15C4   PATCHES INTO 
00049         LDU    WRITE   "W" COMMAND 
00050         ORG    $163A   PATCHES INTO 
00051         LDU    #LOAD   "V" COMMAND 
00052 * 
00053 * 
00054 *ALTER ERROR HANDLIN6 SYSTEM TO 
00055 *ACCOUNT FOR NEW ERROR MESSAGES 
00056         ORG    #1721 
00057         LBSR   ERROR1 
00058         CLR    <$1 
00059         CLR    <$4 
00060         LBSR   ERR0R2 
00061         LBRA   $172F 
00062 *
00063 *
00064         ORG    $E80 
00065 *
00066 *
00067 *NEW ENTRY AREA TO EDTASM 
00068 START   LDX    #$1E00   HE MUST FIRST 
00069         LDA    l$AF     FIX THE THREE 
00070         STA    ,X+      BYTES THAT 
00071         LDA    #$5A     BASIC CLOBBERS 
00072         STA    ,X+      WHILE LOADING 
00073         LDA    #$26     EDTASN+ INTO 
00074         STA    ,X       MEMORY