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CPMREAD.EXE Read diskettes formatted under CP/M CPMDEFLT.EXE Set the default parameters for CPMREAD.EXE Both programs copyright (c) 1988 by Aaron L. Brenner IBM PC is a trademark of International Business Machines, Inc. CP/M is a trademark of Digital Research Inc. A Little Background =================== A few years ago, I worked as a programmer for a company that was using Z80-based machines running CP/M 2.2 for all of their compu- ting. At that time, I had a true-blue IBM PC at home, and I thought that I might be able to do some of my coding work at home. The proverbial fly in the ointment was the fact that all my work had to be put on the company's CP/M-format diskettes, and I had no way (short of buying a commercial package) of going from one format to the other. My first attempt was a quick-and-oh-so-dirty program that did the basic job of reading the CP/M disks on my PC. It was crude, but it worked. Some time later, I read a message on a BBS by someone having the same problem I had just solved. Naturally, I uploaded the program, and thought no more about it. A year later, I began getting phone calls from people who had gotten a copy of the program from a BBS, and were wondering if I would be able to make it work for them. I told them that there was little I could do without either the exact specs for their particular machine, or at least a CP/M diskette to analyze. One gentleman actually sent me a diskette, and I was able to hack up the program so that it was able to read his diskette on my own machine. But, when I sent him a copy of the program, it wouldn't work on his machine. I haven't heard from him since. Just a few weeks ago, a consultant to the company I currently work for mentioned that he had some interesting software, but it was all on CP/M-format diskettes. Aha! I thought, I can hack up my old program yet again, and check out his software. It turned out that it was easier just to apply what I had learned to a brand-new program than it was to hack on the old program. Over the course of the next few weeks, I developed CPMREAD. I have personally tested CPMREAD with the following CP/M formats: Sanyo MBC 1100/1150 256 byte sectors, 40 tracks, 8 sectors per track, 3:1 interleave. EasyData 1024 byte sectors, 40 tracks, 10 sectors per track, 1:1 interleave Visual 1050 512 byte sectors, 80 tracks, 10 sectors per track, double sided, 1:1 interleave. CPMREAD should have no trouble reading ANY soft-sectored format, as long as the diskette drive itself is capable of handling it. CPMREAD ======= Program Installation -------------------- To install CPMREAD & CPMDEFLT, just unARC the files to the direc- tory you want. That's all. Program Operation ----------------- Program operation is quite simple. At the DOS prompt, type CPMREAD followed by a carriage return. CPMREAD will then prompt you to do one of the following: 1. Press the Escape key. This will cause CPMREAD to terminate, returning you to DOS. 2. Press 'S'. This will allow you to Set the disk parameters for your particular system. 3. Put the CP/M diskette into the A: drive, then press any other key to begin reading the disk's directory. Setting the disk parameters --------------------------- Pressing the 'S' key at the opening screen will bring up a menu of options from A to H corresponding to the 8 changeable parame- ters. A) Physical sector size This represents the number of bytes in each disk sector. The standard PClone diskette controller supports sector sizes of 128, 256, 512, and 1024 bytes; therefore, CPMREAD and CPMDEFLT support only these values. B) Maximum directory entries This is the maximum number of 32-byte entries in the diskette directory. Typically, this is either 64 or 128. C) Logical records per block This is the number of 128-byte records in each CP/M block. For most diskettes, this value is 16, which re- sults from a 2k block size. D) Logical records per track This is the number of 128-byte records in each diskette track. E) Logical records per directory entry This is the number of 128-byte records that can be han- dled by a single directory entry. For double-sided dis- kettes under 400k in capacity, this value is usually 256. For higher capacity diskettes, this value is usually 128. F) Number of reserved tracks This is the number of tracks reserved for system use by CP/M. G) Sector interleave This is number of diskette sectors to skip to get sequen- tial sectors. This can vary wildly from one system to another. H) Number of sides This is the number of readable sides on the diskette. Determining the disk parameters ------------------------------- If you are running CP/M 3.0 or later, the SHOW utility will tell you most of what you need to know to run CPMREAD. At the command prompt, SHOW A:[DRIVE] will display all of the necessary parameters except the inter- leave factor. If you are running a version of CP/M earlier than 3.0, you have 2 choices: 1) experiment with CPMREAD, trying as many possibilities as you can, until you succeed; 2) be willing to learn a few things about the innards of CP/M. If you prefer to use trial-and- error, you can skip the rest of this. On the other hand, if you have as little patience as I do, you might be interested in what you can do. I have provided a simple disk dump utility (DDUMP.COM) to help in determining at least some of the necessary diskette parameters. To use DDUMP, just put the CP/M diskette in the A: drive, and type DDUMP <n> where <n> is a number from 0 to 9. This number is the track number to dump. Keep in mind that track numbers start at 0. When DDUMP starts up, the first thing it does is figure out the sector size for you, as well as the number of sectors per track and the number of sides. Once that is accomplished, DDUMP will then output to a file named CONTENTS.CPM those values followed by a hexadecimal dump of the track you specified on the command line. The dump will be in the same basic format as DEBUG or DDT (the CP/M equivalent), with heading lines for each sector. For a sample of the output of DDUMP look at the CONTENTS.CPM file from this archive. The sample CONTENTS.CPM file is from track 2 of a diskette for- matted on a Sanyo MBC 1100. It shows pretty clearly some of the disk parameters for that particular machine: 256 byte sectors, 32 records per track, 2 sides, 3 to 1 interleave, 2 reserved tracks. However, it doesn't show the maximum directory entries, logical records per block, or logical records per directory entry. To figure these out, you need to analyze the dump a little. Sectors that contain nothing but bytes of E5 have probably never been written to, and they can be a good guide to both interleave and max directory entries. If you see a sector full of directory entries followed by one or more sectors full of E5, you know what the interleave is - 3 to 1 if sector 1 is directory, then sectors 2 and 3 are E5. Also, the directory takes up the first data block, so once you get the interleave down, you can tell where the data blocks begin (and the directory ends). With that, you can figure out both block size and number of directory entries. For example, looking at the sample CONTENTS.CPM, you can see that the directory begins in sector 1. Sector 2, however, is obviously NOT part of the directory, as is sector 3. The directory conti- nues in sector 4, which leads one to believe that the interleave is 3 to 1. Since the directory continues into sectors 7, 10, and 13, you know that at least 5 physical sectors are involved - in order, they are 1, 4, 7, 10, and 13. Sector 13 also contains a bunch of E5 bytes, indicating that that is the last USED directo- ry sector. By extrapolating from the interleave, you can see that the directory would also take up sectors 16, 3 and 6. From all this, you know that the directory takes up at least 8 physical sectors, or 16 logical (128-byte) records, yielding 64 directory entries. For there to be more sectors in the directory, sector 9 would ALSO have to contain either directory information or all E5 bytes - it doesn't, so there has to be a maximum of 64 directory entries, and an interleave factor of 3. The other parameters (block size and number of records per directory entry) are best taken from educated guesses: if you know the approximate capacity if the diskette, you have a good idea of these parameters. If the disk can hold up to 400k, the probable values are 256 records per directory entry and the block size is 16 records. If the capacity of the diskette is higher, then you would probably want to use 128 records per directory entry. As you can see, it ain`t always easy. But, with a little mental effort, you can do a lot. And if that always fails, well, try Zen. Seriously, if you really can't figure the parameters out, you can get in touch with me at the telephone number below. We can proba- bly work something out. Copying files ------------- Once the parameters are correct and the directory is loaded, you will be presented with something like: BASCOM.COM submit.com baslib.rel sysgen.com bcload brun.com cpm.sys cref80.com dcop.com ddt.com disintel.com ed.com fbasic.com format.com l80.com lib80.com link.com mbasic.com obslib.rel pip.com rmac.com stat.com BASCOM.COM (253 records) [O]utput path: D:\CPM\C\ Copy: [A]ll, [C]urrent, change [D]isks, [M]arked, [U]nmark all, [Q]uit Arrows move around, spacebar toggles mark The screen display consists of 20 lines of 5 columns of file names, a line for miscellaneous messages, a line showing the size of the currently highlighted file, a line showing the current DOS output path, and 2 lines listing the program options. (In the program, the letters between the "[" and "]" are in high-intensi- ty video.) The options are: [O]utput path This option allows you to set the path that files will be copied to. If that path doesn't already exist, the prog- ram will create it for you. [A]ll This option will copy ALL files from the diskette to the current output path. During the copy, you can press the Escape key to abort. [C]urrent This option will copy the currently highlighted file to the current output path. During the copy, you can press the Escape key to abort. change [D]isks This option allows you to change diskettes without exi- ting the program. It returns to the opening screen. [M]arked This option will copy those files that have been marked. [U]nmark all This option will remove the marks from any files that are marked. [Q]uit This option will exit the program, returning you to DOS. The arrow keys will move among the file names, and the Home and End keys will move to the first and last files respectively. Note: I have yet to try this program out on a diskette that had more than 40 or 50 files. Consequently, the display rou- tines are the least tested parts of the program. If any- one finds a bug in the display, please let me know about it. There is also a known problem when reading high-capacity disks on 1.2MB diskette drives: sometimes the drive can't read them. From the limited information I've gathered, I can't see how to tell the BIOS to expect high-capacity diskettes that are not 1.2MB. I don't have a machine with those kind of drives at home, and I can't do much with the machines at work. If ANYONE out there knows how to do this, PLEASE TELL ME. The only way I've found to read these kind of diskettes is to do some kind of operation with a 1.2MB disk immediately before. Just doing a direc- tory seems to make it work. ***************************************************************** CPMDEFLT ======== CPMDEFLT is just the 'S'et disk parameters option of CPMREAD made into a separate program. The difference is that with CPMDEFLT, you can make permanent changes to the disk parameters. Program operation ----------------- In its current incarnation, CPMDEFLT requires the executable file CPMREAD.EXE for editing. To start CPMDEFLT, use a command line of the format CPMDEFLT [<exe file>[.EXE]] where the file name parameter is optional. The default file name is CPMREAD.EXE. You can even give the file name without the extensions. Once the program is started, it will behave exactly like CPMREAD's "Set parameters" option from the startup screen; all the options are the same. The only difference is that when you're ready to exit to DOS, if you've made any changes you will be asked if you want to save those changes. The disk parameters you see in CPMDEFLT are those that CPMREAD will default to (that's what the DEFLT stands for). The main reason I wrote this program was to permit you, the user, to easily change the parameters to match the disk that you will most often be reading. You could do this each time you ran CPMREAD, but I figure that the program should be making your life easier, not harder. ***************************************************************** In closing ========== I realize that this documentation is pretty scant, but I hope that the programs are simple enough that you won't have trouble (famous last words, I know). Besides, programmers are not really known for their great documentation, just their great (?) prog- rams, right? In the event that you DO have a problem, I can be reached at (617)689-9749 until July 31, 1988. After that, I don't know; I'm going to be moving. If you want to get in touch with me, my mailing address on Genie is A.BRENNER, and I read a lot of the C Echo messages, as well as the Programmer's Echo messages. I have decided to release these programs free of charge, although I retain the copyright. The source code is a different matter. If anyone would like a copy of the source code, I will be happy to send it to them for a small fee of $25(US). I will supply the diskette and mailer. Best of luck. Aaron Brenner 7 July 1988 9 Granite St. Apt. # 14 Methuen, MA 01844 (Until 31 July 1988)