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Text File | 1986-02-13 | 10.7 KB | 231 lines

The disk SIG/M 245, in addition to the usual ancillary files for verifying the checksum, unsqueezing files and unpacking libraries, contains the following new files: FYNDE.COM search files and libraries of files HJELP.COM read HELP files, execute sample programs HJELP.LBR documentation for HJELP.COM MAZE.LBR maze running example for CONVERT TOUR.LBR maze examples in assembly language - - - - - FYNDE.COM - - - - - Ward Christensen's original FIND.COM has been extended several times, by programs which can be found in several SIG/M volumes. Our version FYNDE.COM resembles Unix's "grep" in that a regular expression can be used as a search pattern. Extended once to allow searching through squeezed as well as normal files, it has been extended again to allow searching through library files. A request had been made to incorporate the name of a default search family which would be used when FYNDE was invoked with an empty command line. Presumably the attractive feature of this usage was not so much the default file specification as the fact that the program would then go into a loop, so that the files could be browsed with several search patterns without the need to reenter the file name. Finally, unless one is searching for only one or two items, has a prodigous memory, pencil and paper handy, uses ^P, or has MicroShell in his (her) system, one quickly wishes that there were some way to make a permanent record of a search. A disk file can now be selected to hold the results of browsing through the disk, and is even protected against self-browsing. For lack of space, only the object program for FYNDE.COM is included in this volume, and only the version for the Intel 8080. More through an oversight, library search can only be made in the browsing mode, and not from the command line. When the simple command line FYNDE is typed, SIG*.CAT will be taken as the default specification of the files to be searched, and will respond with a logo and a menu. The menu listing can be refreshed anytime that FYNDE is soliciting options by typing carriage return. Otherwise a letter is expected followed by parameters. Options are H to get a resume of search pattern syntax D FILENAME.EXT to activate an output file S FILENAME.EXT to search a new family of files P LABEL!PATTERN to indicate what to search for Q to quit (^C will not close the output file) D or S file definitions remain active until superseded by a new use of their option. However, D always erases an old file before opening a new one of the same name. Thus if one wants to start over again, the earlier file name may be repeated, but if not the result may be quite distressing. Any change of output file closes the previous file. Q is the only way to quit and ensure that an output file which was in use will be closed. D or S can be followed immediately by their parameter, but there MUST be a space between P and its pattern. This is because P does not use delimiters and spaces quickly become invisible once written. Thus, P followed by TWO spaces will search for text beginning with ONE space. Likewise, spaces at the end of the pattern and before the carriage return count even if that was not intended. In short, P is not free-form; the other options are. Some examples: D FOO.FAW selects FOO.FAW as output file D F*.FAW gives an error message D (FOO) FAW gives an error message D closes output file, stops further output S *.ASM searches assembly sources S (X) *.ASM assembly sources in X.LBR S (X) *.A?M sources might be squeezed S (*) *.* anything that's in a library S (B:X) FOO FOO, member of X.LBR, on disk B S B:(X) FOO no, it's library on disk, not disk w/library S FOO.FAW won't work if FOO.FAW is output file S *.COM will simply skip all those files S ought to return to SIG*.CAT but won't P {?} lists everything (good way to read a file) P (how many spaces was that?) P . lists ends of all sentences, etc P. produces an error message - - - - - HJELP.COM, HJELP.LBR - - - - - HJELP.COM is an outgrowth of the program HELP.COM, whose variants can be found in many SIG/M volumes and elsewhere. The most recent reference is SIG/M 206.02, which could access HELP files irrespective of whether they were squeezed or embedded in libraries. This new version is a very slight but nevertheless extremely useful extension of 206.02, in the sense that binary object programs can be included in the HELP tree structure, and executed as part of the script. Among the many possible applications for this new alternative, we can only regret that our disk is so small that a HELP file explaining the use of FYNDE could not be included. Had this been possible, all the various options, capabilities, and error conditions of FYNDE could be tried out as their description was being read. As it is now, one has to first list this documentation file on the printer, then load and execute FYNDE while reading the listing. That is, if one really bothered to make the listing. Or knew that this file existed! In order to execute the .COM files that one finds in any CP/M system (which means they are all based on an origin 0100H), HJELP must move itself out of the way, just as DDT and some other programs must do. This in turn means that modifications to HJELP must have the same property. The whole process of preparing self-translating programs is cumbersome. For this reason, the file HJELP.LBR contains a submit file HJELP.SUB and a program to execute it, RUN.COM. The details are similar to those of SIG/M 215.04 in which RUN was first introduced. Because of the space reserved to load and execute programs (16K), the space reserved for color images (3x8K), and the size of HJELP.COM itself (4K), there is little space for HELP files (6K maximum). This means that text ought to be quite concise, and that liberal usage of the tree structure of HJELP should be made, and that many small overlays should be planned. It gradually (maybe even rapidly) becomes apparent that HJELP files and their object programs have to be tailored for each other to get the best use out of the combination. Whatever the intrinsic merit of HJELP.COM, its inclusion in this volume allows the file TOUR.LBR to be used interactively to illustrate several applications of Convert. It will be readily apparent to those who study TOUR.LBR carefully that there will be an extensive evolution of programs like HJELP.COM in the presentation of interactive descriptions of existing programs, and the evolution of interactive programs illustrating existing text. - - - - - MAZE.LBR - - - - - The principal motivation for this volume was to present some applications for the programming language Convert, for which SIG/M volumes 213, 214, and 215 are the best current references. Historically, maze problems have been more accessible to list processing languages, especially those with symbol manipulation characteristics, than to languages based on arrays, such as Fortran or its successors. The reason is that only special mazes have regular, array-like structures. As it happens our examples have such regularity, but it is not essential for the techniques which are to be illustrated. MAZE.LBR will have to be unpacked to be used. The reason is that RUN only intercepts CP/M buffered input calls, but not calls directly to BIOS. So that REC programs can generate their own echos to their input, and since CP/M (as opposed to MS/DOS) does not permit echo-free input, REC uses direct BIOS calls to read characters. Until this awkward inconsistency is resolved, REC cannot be RUN from within libraries. MAZE.LBR contains a recent version of REC80 (simply called REC) and a correspondingly updated CNVRT incorporating a superior treatment of CNVRT's runtime library. This deviation from the above mentioned SIG/M volumes is necessitated by the fact that the runtime library was otherwise too large to use REC80 with the 64K of memory of the Intel 8080. In turn our examples feature a CNVRT compiler of Intel 8080 code, which is the reason that none of the programs in this volume have been written for the Intel 8086. Returning to the substantive content of MAZE.LBR, there are two versions of a CNVRT example - a maze running program. The program is simple, and is explained by documentation within MAZE.LBR, save that the CNVRT programs themselves will have to be studied with some care, with reference to previously presented HELP files describing CNVRT. CNVRT.HLP SIG/M = CNVPRG.HLP SIG/M 173.07 CNVADV.HLP SIG/M 203.02 The first version is MAZE.CNV, which compiles into MAZE.REC and can be executed by typing REC MAZE and responding to the moderately cryptic prompt with a list defining the maze. It is completely interactive; rather than preparing the connection list of the maze with an editor and leaving it on a disk, it has to be carefully typed in by hand. This is not the great drawback that it might seem, because MAZE is not practical for mazes with a large number (>10) of nodes. Nevertheless the CNVRT program is short and elegant. The second version, TOUR.CNV, which compiles into TOUR.REC, expects to find its data in a disk file, and creates an assembly listing which will examine the maze about as efficiently as it is possible to do so using an Intel 8080 CPU. It is not possible to HJELP or RUN TOUR either, but HJELP can be used to examine some of the mazes produced by TOUR.REC. Of course, it would be possible to enter into an enormous digression describing the merits of the particular mazes selected, namely Hamilton's dodecahedron problem and the knight's tour on some small chessboards. Suffice it to say that these are interesting problems in and of themselves, and that once the difficulties of programming them are out of the way, it is possible to concentrate on some of the aspects of maze theory. - - - - - TOUR.LBR - - - - - For someone who wants to play with a few mazes, and is not particularly interested in Convert or how the mazes came into existence, the best thing to do is to type HJELP (TOUR) which will gain entrance to a fairly elaborate structure of HELP files and programs to execute. Those who have never seen anything like it before will be impressed, but those who are accustomed to better things (Mammoth Cave and the like --- see SIG/M volume 1 and other early volumes) will quickly realize that there are vast opportunities for those who now want to write interactive scripts and design programs to be exploited by them. HJELP could develop an internal RUN or evolve into a complete operating system without much trouble at all. In the meantime, it will be necessary to read the instructions which TOUR.LBR will proffer concerning the printing of a map, readying pen or pencil, and unlimbering the fingers to have them poised to strike ^S with appropriate rhythm. [end] [Harold V.McIntosh, 20 July 1985]