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Text File | 1984-04-29 | 28KB | 616 lines

COPYFAST.ASM Version 3.5 for IBM 3741 Compatible Diskettes (Originally written by: Chuck Weingart ) ( 2152 W. Iowa ) ( Chicago, Ill 60622 ) ------------------------------------------------------------ This program is placed in the public domain. Selling or licensing of this program is prohibited. (You are encour- aged to give it away to all of your friends). If you make changes that may benefit others, please send the new version to the CPM Users Group, so all may have it. ------------------------------------------------------------ Modified: Version 1.0; by Chuck Weingart October 1980: after the public domain Tarbell disk copy program (does not require a Tarbell controller) Version 1.1; by Kelly Smith January 21, 1981: ( >>>modifications undocumented <<< ) Version 1.2; C. Strom February 12, 1981: corrected typo in OBJMSG when SINGLE true; added a CR. Version 2.0; by Chuck Weingart February 16, 1981: Changed messages added in V1.1 and 1.2 back to upper case - some people have terminals that dont handle lower case. Version 2.1; C.W. February 18, 1981: added code to check console port for Ctrl-C abort condition during copy, and misc code to help in CP/M 2.2 systems that block and deblock from large sectors. Version 2.2; C.W. February 24, 1981: added auto size check. Added interleave table suitable for very fast disk controllers. Version 2.3; C.W. March 2, 1981: Change all references to EXITCP to EXIT so that user gets a chance to put in system disk before program re- boots CP/M. VERSION 3.0; C.W. March 6, 1981: Check if given number of buffers will overlay the BIOS and reduce accordingly. Moved comments to DOC file to keep the source editable in one pass, and add more explanation to the comments on sector sizes and read skewing. Version 3.1; C.W. March 10, 1981: Added TSKEW and code for track skewing to increase speed for fast controllers. Separated read and write error checking: NUMERR now applies to each track read, but to each entire write pass. Version 3.2; C.W. March 18, 1981: Corrected read skew bug noticed by Steve Bogolub. Added CR,LF to the read and write error messages that got deleted in version 1.1 Added WRSWCH, WRCODE, WRTAB to help solve problems with CP/M 2.2 blocking with some manufacturers CBIOS routines. Version 3.3; C.W. March 22, 1981: Added DIFFTRK (ability to copy from different tracks) in order to be able to unpack UCSD Pascal disks. Version 3.4; C.W. May 9, 1981: Fix bug in read error recovery that caused bad read to repeat forever. (Took me two attempts. No branch to TRYRDA.) Changed NUMERR to 4. Version 3.5; C.W. May 16, 1981: Add parameter for specifying the range of tracks copied. Removed CRLF between source and object messages. Moved INIT message to one-time code. Display # of buffers used if insufficient space. Echo source and object drives. Home drives after the copy is complete (to flush buffers). Note to subsequent modifiers: Please note the specific changes you make to the code, so that others can keep track what you have done, even if it is just lower case messages. ------------------------------------------------------------ This program will copy the data area of one CP/M disk to another (thats tracks 2 - 76), as fast as possible. All data written is read back to verify that the write was successful, and multiple tracks are copied in one pass, for speed. The version as supplied assumes that the controller CRC checking is sufficient for verification, but an assembly option allows complete byte-by-byte comparison on the read back. It is possible to copy only part of a disk, moving a block of tracks from one disk to a different part of another. The program as supplied will automatically determine the size of the CP/M system and adjust the number of buffers accordingly. For example, it can copy four tracks at a pass in a minimum (16K) system, and 18 tracks at a pass in a max- imum system (64K). A fixed-buffer option is also available: the number of track buffers, and hence the minimum size, can be changed to suit your system. Only standard CP/M CBIOS calls are used to access the disk, no BDOS calls, so the BDOS and CCP can be overlaid by the track buffers. No other CP/M functions are assumed. North Star CP/M or UCSD Pascal users should be able to modify this program easily to run on their systems. COPYFAST will allow a disk to be copied on a one-drive system, as an assembly option. A version with 18 buffers (64K) will require only 5 complete swaps. ------------------------------------------------------------ Three assembled versions of the program are supplied, for your convenience. They are called CPYFST3F.COM for very fast disk controllers (such as CCS 2422), CPYFST3M.COM for controllers (such as Micromation) that cannot write a track in one revolution, and CPYFST3S.COM for controllers (such as Versafloppy) that must interleave both reads and writes. I recommend that you try each of the three programs to see how fast they run on your system. The only difference between them is the read and write interleave. All three versions do read-after-write checking and automatically determine the number of buffers to use in the copy. If all three COM files run very slowly you may have a slow controller or an inefficient CBIOS, and it will be necessary to examine this documentation closely and edit the source to fit your requirements. The source is supplied for CPYFST3F.COM and I list all the differences for CPYFST3M.COM and CPYFST3S.COM later in this file. ------------------------------------------------------------ To run, just type: CPYFST3n<cr>. The program will then request the source and destination disks, (drives A - F) and give you a chance to put in the correct disks in the drives before continuing (or quit by entering CTRL-C). When done, the program will ask if another pair of disks is to be copied, and the process repeated. The range of tracks copied can also be specified in a single character parameter after the program name. That is: CPYFST3n X<cr> where X is one of the following values: A All 0-76 Entire disk D Data 2-76 CP/M data area F First 2 CP/M directory track L Last 76 Last track on disk O One 1 Track one, UCSD directory P Pascal 1-76 UCSD Pascal data area S System 0-1 CP/M bootstrap Z Zero 0 Track zero, UCSD bootstrap (Note: only complete tracks are copied) Only the first character is checked, so the full word may be spelled out, if desired. Invalid letters will cause an error message, and the program will not run. The default range, currently 2 to 76, is given in the program at locations 12DH and 12EH. The console is checked often to see if the operator has en- tered a CTRL-C, so it is possible to abort the program even during the actual copy. If the number of buffers specified during the assembly is too large, that is, if the CBIOS would be overlaid during the copy, then a message will be issued and the program will reduce the number of buffers to fit the system. ------------------------------------------------------------ This source can be assembled with the CP/M ASM or MAC. COPYFAST runs on an 8080 or similar CPU, CP/M 1.3, 1.4 or 2.2, or Cromemco CDOS disk operating systems as supplied, and does not use any particular type of controller or disk hardware, other than the "standard" 77 track, 26 sector-per- track disk. The latter two numbers can be easily changed in the source. The program currently assumes that the disk controller can read and write the disk in just one revolution. This means that an entire track can be written and checked in two revolutions. Two alternate interleave tables are included in the source if this is not possible with your hardware, and any sector interleave can be used by changing the table. An assembly option is available to allow interleaved reads, if your disk controller cannot keep up with the program. An- other option is available if read interleaving is not used, to increase the read speed by changing the first sector read on each track so the read will start as soon as possible af- ter the seek is complete. This program has been run unaltered on a Micromation Doubler disk controller with Shugart drives, the Califor- nia Computer Systems model 2422A disk controller, a Tarbell single density controller board, and a Cromemco 4FDC board (the latter two use a WD 1771 chip) with Persci drives, and the worst copy time was 122 seconds. A typical time is more like 56 seconds (CCS controller). Faster hardware means faster copies. The program is written with all necessary constants in eq- ates, so modifying it for some other type of sector size, for example, should be fairly easy. In fact, Roy Lipscomb, a member of the Chicago Area Computer Hobbyist Exchange, wrote a program called FOTOCOPY for the Thinkertoys DJ2D controller after asking me a few questions about the purpose of the BIOS calls. I believe he simply modified the CBIOS jump table in the program to point to the on-board EPROM of the DJ2D, and changed the various equates to what was necessary for a 512 byte double-density disk. He reports really fantastic copy speeds for that controller using my methods. The only bad comments I have heard to date is that the pro- gram isnt fast with the Txxxxxl and Txxxxxxxxy versions of CP/M. The two cases I got personally involved with turned out to be very much the same thing: poorly written sector blocking/deblocking routines. In one case, I suggested that the interleave table be changed to 1,2,3,4,9,10,11,12,... in a 512 byte (128*4) sector. That way, the first four "sectors" fit into the first physical sector, and then the four "sectors" in the third physical sector are done, and so on. The second case turned out to be a bug in the DEBLOCK code that Digital Research is suggesting be used in CP/M 2.x. The source they are distributing will miss blocks and/or cause unnecessary I/O to the disk. If you use their code, do so with care. One manufacturer of controller boards is supposed to be supplying a CBIOS that checks the density of the disk on every single track. Obviously, that will really slow down everything, including COPYFAST. Note: for CP/M 2.x users with single drive systems and sec- tor sizes greater than 128, the program now homes the disk before swapping the disk (at label STARTL). This is to give the CBIOS a chance to write the last sector. If homeing the drive is not enough to cause your CBIOS to empty the buffer, then add any code at that point that will do so or change the CBIOS. I recommend the latter, since homing the drive is only done in such special cases such as a reboot or a disk change. ------------------------------------------------------------ Quick course in floppy disk functions: The IBM 3741 floppy disk has 77 tracks, or positions where the read/write head can be. There is always a counter some- where in the BIOS and/or disk controller board that gives the current position of the currently selected disk. It usually takes about 15ms to move the head one track (in or out), and can take up to 120ms to move the heads from track 76 to track 0. Track zero, by the way, is at the outside edge of the disk. The diskette rotates at 360 RPM, or 167ms per revolution. The standard format specifies that there are 26 128-byte sectors, or records, on each track. A little quick arithmetic will give you the results that it takes maybe 6ms or slightly longer for one sector to pass under the head. Since the disks are always rotating, there is always some sector now under, or about to be under, the head. It can also take an entire sector for a floppy disk controller to find where it is, assuming that the disk head was suddenly and randomly loaded, or moved to another track. Furthermore, many floppy disk controllers cannot even read one sector after another, or perhaps they can read, but cannot write that fast (since writing requires that some of the gap bytes be written before and after the data, where reading can start just after the address mark, and stops when the first gap byte after the data stops.) Another major consideration for copy programs is that it takes maybe 30ms for the head of a disk drive to be loaded onto the surface of the diskette, and you dont like to do that often, since the impact could cause wear. What does this all mean? Well, suppose you want to write a copy program. First, you have to tell the controller what track to start at, and to load the head. That might take 30ms to load the head and 50ms to move the head to the right track. Now, you want to read sector one, but sector one is not there right now. You might have to wait 80ms for sector one to come around. (there is no CBIOS command for "read the next sector, whatever that is" and some controllers cannot do it at all) After you have read sector one, maybe you then want to read sector two. Unfortunately, you waited too long to decide, and the head is now halfway through sector two. So, the controller waits 166ms for the start of sector two to come sround again. You would have been better off if you asked for the odd sectors first (1,3,5...) and then gotten the even sectors on the next revolution. That would take only 334ms all in all. That is what is called read interleaving, or skewing for short. There is another type of skewing, called track skewing. That occurs when you have read the last sector, sector 26 for example. Now, you order the disk to move the head to the next track. That took 15ms, and in that time sectors 1, 2, and part of 3 rotated by under the head. So, if you tell the controller to read sector 1, then you have to wait until sector 1 rotates by again, about 150ms. If you could start this read at sector 4, and read everyting sfter that, you would not waste as much time. That's track (or seek) skewing. In order to make a copy in the shortest time, this program does all of the following: 1. Reads as many tracks as possible into core, and then switches to the other drive to write. This will minimize the number of times the head on each drive has to be loaded. 2. Does all reads as fast as possible, with any skew that is needed to achieve that. The fastest possible is no skewing at all, of course. The skewing pattern is in a table for easy manipulation. 3. Does all writes as fast as possible, with any skew that is needed. The write skew does not have to be the same as the read skew, because some controllers can read faster than they can write. 4. Allows track skewing on the main read so that the track can be read with as little rotational delay as poss- ible. The read after the write does not need this skewing, because there is no movement between the write and the following read. The program does one thing that slows it down: it checks the data that is written by reading it back. If you are very confident of the reliability of your system, controller, and disks you could skip that step. I think that starts at label WT3 in the program, and the code could be commented out. On a normal controller, that step adds about 12 sec- onds to the copy time, and I think it is worth it. ------------------------------------------------------------ Assembly-time variables that can be changed: SINGLE: TRUE for single drive copy program RSKEW: TRUE if read interleaving needed. If FALSE, the program will read the sectors sequentially (1,2,3, 4,...) When TRUE, you should modify the read skew table (READTAB) to fit your particular requirements. Read skewing is used on the initial read and on the read-after-write check. (This is FALSE for CPYFST3F and CPYFST3M and TRUE for CPYFST3S.) TRSKW: TRUE if track to track read skewing is desired when there is no read skewing. TRSKW may be TRUE only when RSKEW is FALSE. TSKEW gives the value of the track sector skew. (This is TRUE for CPYFST3F and CPYFST3M and FALSE for CPYFST3S.) DOCOMP: TRUE if byte-by-byte comparison is desired on read-after-write check. WRSWCH: TRUE if it is necessary to pass your CBIOS different values in reg. C during writes. See the CP/M 2.2 Al- teration Guide for the purpose of this value in reg. C. If TRUE, it will be necessary to edit the WRTAB table to fit your particular requirements. If FALSE, the value in reg. C will be that given in WRCODE, normally 2. NUMERR: The number of errors before counting as a permanent error. The error counter applies independently to each track read, but applies to each entire write pass. That is, the program will try to read each track NUMERR times, and will quit and then go to the next track. However, when writing, the program will stop writing when NUMERR errors have occurred on the current pass, and then it will start a new read/write pass at the track after the track with the write error. The read and write error counters are independent, since they are supposed to be two different disks. SDLAST: the number of sectors per track. This value also de- termines the size of the READTAB, WRITAB, and WRTAB tables. TSKEW: The value of the track to track read skew. This applies only if RSKEW is FALSE, that is, no read sector skewing. This is to allow even faster reads when a fast disk controller chip is used. The reason is this: after the last sector on the track is read (usually 26), the program must move the arm on the disk to the next track. This takes time, of course, and so the disk has rotated a bit. So, if the next sector wanted is the first, then the program has to wait until the disk has rotated a- round all the way back to the start. But if the program could then start with sector 8, say, there would be no waiting. Of course, the program would have to read sectors 1-7 after reading number 26, and then move the arm. So, then it should start reading the next track at sector 13, and so on. In this case, the value of TSKEW is 7. The program will always start a pass on sector one, but will not start at sector one if the track skew gives a value greater than SDLAST. That is, track skewing is a modulus function. If TSKEW is 7, the poss- ible starting sectors are 1,8,15,22,3,10,17,... if SDLAST is 26. Track skewing is used only during the initial read from the source disk. On the read-after-write check, the write skew table is used to compensate for the head load and seek times. This value is ignored if TRSKW is FALSE. SECSIZ: number of bytes per sector. Read the comments re- garding the sector size below if you plan to adapt the program to some other type of disk format. For CP/M compatible BIOS routines, this is always 128. WRCODE: If WRSWCH is FALSE, this is the value passed to the CBIOS sector write routine in reg. C. See the CP/M 2.2 Alteration Guide for details of this value, but it is normally 2 for this application. FIRSTRK:the first track copied. If the starting track for the source and object disks are not identical, then this figure applies to the object disk. Note: this value is normally the track where CP/M places the directory. It is assumed that the bootstrap starts at track 0 and ends on track FIRSTRK-1. LASTRK: the last track copied plus one. The number of tracks copied is normally LASTRK-FIRSTRK. These latter two values specify the copy range, and the program can be run in other ways by the param- eter given when COPYFAST is first invoked. FIRSTRK and LASTRK specify how the parameter will actually be interpreted. All 0-(Lastrk-1) Entire disk Data Firstrk-(Lastrk-1) CP/M data area First Firstrk CP/M directory track Last (Lastrk-1) Last track on disk One 1 Track one, UCSD directory Pascal 1-(Lastrk-1) UCSD Pascal data area System 0-(Firstrk-1) CP/M bootstrap Zero 0 Track zero, UCSD bootstrap (Note: only complete tracks are copied) BUFFNU: the number of full track buffers that will fit into your system. This figure includes the space used by the read-back buffers, if used. Zero or minimum 2. If you wish auto-size determination, set BUFFNU to zero, and the program will use all space up to, but not including the CBIOS routines. With the current specification of 26 sectors per track, the program will require at least 39K for buffers alone if BUFFNU is 12, and so should run in a 42K system minimum. (12 * 128 * 26 = 39936 plus 3K for the CBIOS and program). I recommend that BUFFNU be minimum of 2 if you do not want auto-size determination. DIFFTRK: is the difference between the source and the object track numbers. That is, this quantity is added to the object track number to get the source track number. This is so that the program can move tracks around from one disk to another. This is normally zero. DIFFTRK is ignored in a single-disk program. For example, to copy tracks 25 to 49 from a UCSD Pascal disk to tracks 0 to 24 of an empty disk, set FIRSTRK to zero, LASTRK to 25 (24 plus 1), and then DIFFTRK has to be 25(source) - 0(object), or 25. DIFFTRK is used only when the default copy range is used. If one of the range parameters is specified, then DIFFTRK will be set to zero automatically. The last four quantities are in single-byte constants in the program, and can be modified by DDT to alter the charac- teristics of the program to suit your needs. They are found at label TRKSRT in the program, at locations : FIRSTRK 12D LASTRK 12E BUFFNU 12F DIFFTRK 130 I change these values to create various versions of Copy programs. These values are defaults, and they are not used if the range parameter is specified, (or in the case of BUFFNU, if CP/M is too small). Note: some distributors of CP/M (such as Micromation), supply a CBIOS that alters the BDOS routines, whether or not the BDOS is present there. This means that you cannot safely let COPYFAST take all space up to the CBIOS, because the CBIOS will modify the contents in the highest buffer in the mistaken idea that the BDOS is there. This usually means that the CBIOS cannot be used for UCSD Pascal, either. Note: if you are modifying this program for use with other than 128 byte sectors, and this has been done successfully, you MUST change the code at labels RT3, WT3, and WT4. The change generally consists of adding a few more DAD H lines to the code. There are currently 7 of these, since 128 = 2 to the 7th power. If you are going to be processing 1024 byte physical sectors, then add 3 more DAD H instruction to each of the three places indicated, because 1024 = 2 ^ 10. Do not change the number if you are running with a CBIOS written to deblock the physical sectors into 128 byte logical sectors, as all CP/M 1.x and 2.x compatible BIOS routines do. In such cases, the number of "sectors" per track is changed instead, exactly the same as CP/M itself is told. The CBIOS in that case will put the logical sectors into one physical sector before doing the write. It will of course be necessary to change the sector skew tables to something that matches the capabilities of the disk controller and the blocksize. You must understand exactly how your CBIOS blocks and deblocks from the physical sectors before you can make up a good skew table. ------------------------------------------------------------- Alternate interleave table for slower controllers. The sectors are listed in the order they will be written to disk. NOTE: the peculiar ordering is due to the fact that some disk controllers cannot switch between writing sector 26 and reading sector 1 in time - so the table begins with 25, proceed up every other sector, and ends with number 24. While the head is passing sectors 25 and 26, the program will be switching to read back the entire track. There is generally no problem starting with sector 25, because simply moving the head after the previous read on most drives will take about one half revolution. This table was determined empirically using Shugart drives and doing actual tests with two different types of controller boards, and it is the fastest variation found. Change at your own risk. DB 25,1,3,5,7,9,11,13,15,17,19,21,23 DB 26,2,4,6,8,10,12,14,16,18,20,22,24 (This table is used in CPYFST3M.COM and CPYFST3S.COM) The following table is recommended for those whose controllers cannot write even every other sector. There is no peculiar starting sector here because the interleave ends on sector 24, and that is the same as the table above. This might be a better choice for a "universal" table. DB 1,4,7,10,13,16,19,22,25 DB 2,5,8,11,14,17,20,23,26 DB 3,6,9,12,15,18,21,24 It is likely that if you require one of the alternate write skew tables, then you will also have to have read skew. So, you should also make RSKEW equal to TRUE and modify the read skew table to run as fast as possible. ------------------------------------------------------------- Users of double-density controllers may be interested in what I did with mine. My BIOS is written so that a double density disk is considered as two single disks, that I refer to as "the front half" and "the back half". With three drives, A, B, and C are the fronts, and D, E, and F are the back. A single density disk is only front. Each track has 3328 bytes (26*128) bytes of data for the front half, and 3328 bytes for the back half. The way COPYFAST works makes it possible to copy the front half to the back, and vice-versa, and I dont have a lot of funny versions of programs written exclusively for a particular density disk. Two "disks" per floppy also means twice the directory space. My BIOS is also written to check the disk density whenever the disk in HOMEd, which COPYFAST does before starting. The only hardware dependencies in my system are in the disk initialization program and in the BIOS. ------------------------------------------------------------ Suggestions for improvements: 1. Ask if you really wanted to copy a disk if track 2 (the directory) was completely empty i.e. all E5's 2. Better error checking .. the program reports only one comparison error per track right now. 3. Have an option where it only compares two disks to see if they are the same. 4. Check for CP/M 2. If so, use the disk attribute table for information like number of sectors, number of tracks, etc. 5. Could this thing be modified for hard disk backups?