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22NICE - A NEW INSYSTEM CP/M 2.2 EMULATOR Version 1.2, July, 1988 Copyright 1988, C. P. Guzis SYDEX 153 North Murphy Ave. Sunnyvale, CA 94086 (408) 739-4866 All Rights Reserved NOTICE THIS IS NOT FREE SOFTWARE! If you paid a "public domain" vendor for this program, you paid for the service of copying the program, and not for the program itself. Rest assured that nothing ever gets to the originators of this product from such a sale. You may evaluate this product, but if you make use of it, you must register your copy. We offer several inducements to you for registering. First of all, you receive the most up-to-date copy of the program that we have - and we do update the product on a regular basis. You also receive support for 22NICE - which can be quite valuable at times. And finally, we have a few utilities not included in the evaluation package. Make no mistake, however - this is a fully functional version of 22NICE and not "crippled" in any way. REGISTRATION INFORMATION The non-commercial single-user registration fee for 22NICE is $30.00 US. This registration also includes a copy of 22DISK , a CP/M diskette conversion utility package. The commercial and multisystem site fee for 22NICE is $75.00. Send a check or company P.O. for the appropriate amount to: SYDEX 153 North Murphy Ave. Sunnyvale, CA 94086 Please indicate what product you are ordering and if you have a requirement for 3.5" media. We normally ship 5.25" 360K diskettes, but will furnish 3.5" 720K media upon request. DISTRIBUTION NOTICE This is "user-supported" software. You are hereby granted a license by Sydex to distribute this evaluation copy of 22NICE and its documentation, subject to the following conditions: 1. 22NICE may be distributed freely without charge in evaluation form only. 2. 22NICE may not be sold, licensed, or a fee charged for its use. If a fee is charged in connection with 22NICE , it must cover the cost of copying or dissemination only. Such charges must be clearly identified as such by the originating party. Under no circumstances may the purchaser be given the im- pression that he is buying 22NICE itself. 3. 22NICE must be presented as a complete unit, in- cluding this documentation. Neither 22NICE nor its documentation may be amended or altered in any way. 4. By granting you the right to distribute the evalua- tion form of 22NICE , you do not become the owner of 22NICE in any form. Any other use, distribution or representation of 22NICE is expressly forbidden without the written consent of SYDEX. CP/M, CP/M-80 and CP/M 2.2 are trademarks of Digital Research. MS-DOS is a trademark of Microsoft. IBM PC, PC-XT and PC-AT are trademarks of International Business Machines. V20, V30, uPD70108, uPD70116 are trademarks of NEC Electronics. Some products of Lear-Siegler, Kaypro, Osborne and Televideo are also trademarked. Table of Contents 22NICE IN BRIEF..............................................1 COMMAND SYNTAX CONVENTIONS...................................1 USING THE 22NICE CP/M EMULATOR...............................2 HOW 22NICE WORKS.............................................3 INSTALLING 22NICE............................................5 THE GENCOM UTILITY - GENERATE A PRE-LOADER...................6 LOCATING CP/M PROGRAM FILES..................................9 A SAMPLE 22NICE INSTALLATION................................10 USE OF CP/M SUBMIT AND XSUB.................................12 USER NUMBER SUPPORT.........................................13 SAVING MEMORY IMAGES - THE CSAVE COMMAND....................14 MISCELLANEOUS TOPICS........................................14 Accessing I/O Ports........................................15 Accessing PC Memory........................................15 IOBYTE Support.............................................15 Physical Disk Addressing...................................16 Maximum Program Size.......................................16 Disk Drive Reassignment....................................16 IN CLOSING..................................................16 OTHER SYDEX PRODUCTS........................................17 22NICE IN BRIEF 22NICE is a Z-80/8080 CP/M 2.2 emulator for use on PC-compatible computers. The 22NICE CP/M Emulation package offers the follow- ing features: * Emulate 8080/8085/Z-80 processors with or without NEC V-series chip installed. * Provides terminal emulation for most common CP/M machines with terminal types for Osborne, Kaypro, Heath/Zenith, Morrow, Actrix, DEC VT-100/VT-52, Televideo 925 and LSI ADM-3X. * Supports CP/M user number to DOS subdirectory transla- tion. * Allows use of DOS "pipes" and utilities with CP/M programs. * Supports a complete set of BDOS and BIOS function in- terfaces, including direct disk read/write. * CP/M programs are fully integrated into the DOS en- vironment; the user is unaware that a program is CP/M- or DOS-based. All this for a nominal registration fee! You'd easily pay over a hundred dollars for a commercial package with far fewer cap- abilities. In addition, we include the 22DISK CP/M-to-DOS con- version package with every 22NICE registration. COMMAND SYNTAX CONVENTIONS In order to discuss the general form of various 22NICE commands, a number of conventions have been adopted in this document: (1) All commands are assumed to be followed by depression of the ENTER key. Sometimes this key is referred to as RETURN or CARRIAGE RETURN. (2) All upper-case (capital) letters are entered exactly as shown in the command description. For instance, CFMT is entered as depressions of the "C", "F", "M" and "T" keys. Actual case of the entered characters is ir- relevant; that is, either upper- or lower-case letters may be entered. (3) Any item enclosed in quotes (") refers to a name of a particular type of item and is not to be entered literally. For example: "CP/M file" refers to a general CP/M file designator and NOT the characters "CP/M file". (4) Any item enclosed in parentheses ("(" and ")") refers to an item which may be omitted from the command line. For example: ("disk type") refers to a disk type item which may be left out com- pletely from the command statement. (5) Any blank character may be replaced by more than one blank character. These conventions will be used throughout this document with ad- ditional explanations where required. USING THE 22NICE CP/M EMULATOR The emulation of 8080 and Z-80 processors on the PC is not a recent development. Almost since the beginning, co-processor cards have been available for the PC and various efforts have been made to include CP/M 2.2 support in the general scheme of things. CP/M 2.2 on an MS-DOS machine is a tempting prospect - after all, MS-DOS was based on CP/M 2.2 (and not CP/M-86). In 1985, NEC introduced a pin-compatible 8088 work-alike called the uPD70108 or V20. The curious thing about this chip is that it's really two processors in one - an 8088 for PC-based ("16 bit") software, and an 8080 for the older CP/M ("8 bit") software. Switching between the modes is done with special machine instructions. What could be a more natural product than a CP/M emulator running on the PC? It happened that a lot of people got this idea and offered a host of packages differing in appearance and function to do essen- tially the same thing - emulate a CP/M environment. Sydex developed 22NICE , but decided against marketing it for or three years, primarily because of the number of similar products al- ready being offered. The fuss has died down now. Intel is still suing NEC on charges of copyright infringement over the V20, but by and large, CP/M support is of no great interest. The V20, alas, would not emu- Page 1 late a Z80, and it does have a few unfixed "bugs" in its emula- tion mode. Besides, PC-AT clones are really selling now and you can't drop a V20 into one of those. So Sydex has dusted off its emulator, 22NICE and put it out in the shareware market. 22NICE offers the following advantages over its competition: * 22NICE will use a V20 if it's present and do software emulation if it's not. This means that you can run your old CP/M programs on your PC-AT. * 22NICE contains an emulator for both 8080 and Z80 processors. In addition, 22NICE has a "test" mode, which will allow you to identify the appropriate processor that you need to emulate. It will also tell you if your program will run afoul of one of the V20 bugs. * 22NICE supports a user number-subdirectory mapping that allows your CP/M program to access DOS's directory structure. * 22NICE contains terminal emulation routines for a few common terminal types which will usually allow you to run a program without re-installing, * If terminal emulation isn't important, 22NICE allows your program to use DOS console input and output facilities. This means that you can use a CP/M program as part of a DOS "pipe". * And finally, 22NICE fits CP/M into the DOS environment - CP/M programs use the DOS facilities and are not dis- tinguishable from other DOS programs. This means no special CP/M-like command interpreter is needed. Together with the diskette data conversion programs, support of CP/M 2.2 applications on a PC can really be painless. HOW 22NICE WORKS There are several ways to implement a CP/M-like operating en- vironment on a PC-class computer: (1) Emulate an 8080 or Z-80-based computer system and run CP/M 2.2 more or less "straight out of the box". This approach leads to difficulties in making use of DOS data files and system functions. It also requires that you "shift gears" mentally each time you make the tran- sition from CP/M to DOS and vice-versa. Page 2 (2) Emulate the CP/M operating environment and provide 8080 and Z-80 emulation. This might take care of some of the DOS data interchange problems, but "crossing over" to DOS is difficult and few of the benefits and resource of DOS are available to CP/M users. (3) Support the CP/M I/O interface and provide 8080/Z-80 emulation, but leave DOS in control as the host operat- ing system. This involves the greatest effort and re- quires an intimate knowledge of CP/M 2.2 and MS-DOS in- ternals to really work properly. However, all DOS facilities are at your disposal and "mixing" of CP/M and DOS applications happens naturally. This is the approach taken in 22NICE . 22NICE puts the bulk of the emulation in a DOS installable device driver package called 22RES.SYS . 22RES not only contains support for CP/M functions, but also provides software emulators for both the 8080 and the Z-80 instruction sets. CP/M programs are loaded by having DOS first execute a "pre- loader", which provides information to 22RES about the program to be executed. 22RES then allocates the necessary memory, loads the CP/M program code, and begins emulation. A CP/M executable file normally has a file name extension of "COM". This creates problems, however, with existing DOS programs having the same extension. DOS does no checking on the contents of "COM" files -- executing a CP/M file in DOS 8088 mode could lead to disaster. 22NICE handles this by renaming all CP/M executable files with a "CPM" file name extension. CP/M programs, therefore, are not directly executable by DOS. The "pre-loader" for each CP/M program carries the "COM" name extension and the name of the CP/M program to which it is related. The pre-loader is short -- about 600 bytes, but one is needed for each CP/M executable file. This can get to be a nuisance if you're not running with a fixed disk, so we've also provided a "bound" program form, where the CP/M program is combined with the pre-loader in a single program file. This "pre-loader" concept is very powerful - it allows different programs to execute with different operating parameters. MicroPro's WordStar, for example, best runs in a mode where the numeric keypad is re-mapped to provide WordStar cursor movement codes. CP/M system utilities, however, best run with no terminal emulation, allowing console input and output to be redirected if desired. One program may require Z-80 software emulation, where another might not. Page 3 22NICE has been in use within Sydex for some time - currently we have it running in AT's and XT's and on at least one CompuPro 8086 machine. INSTALLING 22NICE The files associated with CP/M emulation are the following: 22RES.SYS the resident support driver. CUSER.EXE user number information utility. GENCOM.COM generate a DOS *.COM file. CSAVE.COM SAVE command a la CP/M SAVE To install 22NICE on your system, you'll need to insert a line in your CONFIG.SYS file on your boot drive. The line should read as follows: DEVICE=22RES.SYS A statement to insert the required text into CONFIG.SYS is: ECHO DEVICE=22RES.SYS >X COPY /A \CONFIG.SYS+X CONFIG.SYS DEL X You may also use any ASCII text editor, such as EDLIN, to do the same thing. Make sure that 22RES.SYS gets placed in the root directory on your boot disk so DOS can access it. You can also put it in another directory and include the path specification with the file name on the DEVICE= line. For example, DEVICE=\CPM22\22RES.SYS 22RES needs two hardware interrupt vector slots to function. If you don't specify which interrupt to use, 22RES starts looking for an available one beginning with interrupt 128. If you need to specify the interrupts to be used, the CONFIG.SYS line should look like this - DEVICE=22RES.SYS <i1> <i2> where <i1> and <i2> are interrupt ordinals expressed as decimal numbers. If just <i1> is specified, interrupt vectors <i1> and the one immediately following (<i1>+1) will be used. At this point, it is assumed that you've gotten your CP/M files over to your PC somehow. Remember that CP/M program files with an extension of "COM" need to be renamed to have an extension of Page 4 "CPM". The 22DISK conversion utilities do this automatically, but if you've used some other means to obtain your files, you'll need to rename them manually. THE GENCOM UTILITY - GENERATE A PRE-LOADER The GENCOM utility is used to create "COM" files which can be loaded and executed by DOS. These files interface to the 22RES driver and serve as pre-loaders for execution of the associated CP/M program ("CPM"-type) files. GENCOM produces a very short (about 600 bytes) DOS program file which, when executed, performs the following actions: (1) Determines if 22RES has been installed. If not, an er- ror message is issued and no further action is taken. (2) Passes an information packet concerning the operating environment for the CP/M file and the name of the file to be executed in emulation mode. (3) Relinquishes control to 22RES for actual CP/M program loading and execution. Note that a "COM"-type file produced by GENCOM serves both as an interface between DOS and 22RES and also as a container for in- formation concerning the CP/M program environment needed. In fact, GENCOM does not even need to know that a particular CP/M program file exists - the file location and subsequent execution is handled by 22RES. The syntax of the GENCOM command is as follows: GENCOM "file" (DISPLAY="dtype") (KEYBOARD="ktype") (PROCESSOR="ptype") (BIND="filename") "file" is the name of the CP/M program file to be executed, and is specified without a file extension. No DOS path names are allowed here, just the name of the CP/M com- mand for which a 22RES interface file will be genera- ted. DISPLAY="dtype" is optional and specifies the type of con- sole display to be emulated. Any of the following may be specified for "dtype": NONE - Use DOS for output. No special handling of characters is performed unless the ANSI.SYS device driver has been specified in the DOS CONFIG.SYS file. If the DISPLAY expression is omitted, this Page 5 is the default. If program output is to be "piped" to another program or file, NONE must be specified. TVI920 - Emulate a Televideo 920/925 series terminal. ADM - Emulate a Lear-Siegler ADM-3/ADM-31 type ter- minal. OSBORNE - Emulate the display on an Osborne I/II/Nuevo computer. KAYPRO - Emulate the display on a Kaypro I/II computer. ANSI - Emulate an ANSI (DEC VT-100) display. VT52 - Emulate a DEC VT-52 display. H19 - Emulate a Heath/Zenith H19/Z19 or H89/Z89 dis- play. DISPLAY may be abbreviated to DIS. KEYMAP="ktype" is optional and specifies the map for the console keyboard. Any of the following may be specified for "ktype": NONE - Use DOS for input. No special handling of keyboard characters is performed. If the KEYMAP expression is omitted, this is the default. If keyboard input is to be "piped" from another program or file, NONE must be specified. TVI920 - Emulate a Televideo 920/925 series terminal keyboard. ADM - Emulate a Lear-Siegler ADM-3/ADM-31 type terminal keyboard. OSBORNE - Emulate the display on an Osborne I/II/Nuevo computer keyboard. WS - causes the keypad keys to generate codes suitable for MicroPro WordStar. KAYPRO - Emulate the keyboard on a Kaypro I/II com- puter. ANSI - Emulate the keys on an ANSI (DEC VT-100) ter- minal. VT52 - Emulate the keyboard on a DEC VT-52 terminal. Page 6 H19 - Emulate the Heath/Zenith H19/Z19/H89/Z89 keyboard. KEYBOARD may be abbreviated as KEY. PROCESSOR="ptype" is optional and specifies the processor emulation type required for this program. Any of the following may be specified for "ptype": V20 - Indicates that 22RES should use the hardware emulation capabilities of the NEC V20 or V30 processor, if one is installed in this computer. If no V20 or V30 processor can be found, an 8080 software emulator will be automatically used. V20 is the default if the PROCESSOR expression is omitted. E8080 - specifies that 22RES should use an 8080 software emulation, even if a V20 or V30 is present. E8080 is primarily used when the TEST mode indicates that there will be problems using the V20 or V30 hardware emulation facility. Z80 - specifies that 22RES should use a Z80 software emulation. Note that the NEC V20 and V30 do not support the extended instruction set of the Z80 processor. TEST - specifies that 22RES should implement a Z80 in- struction set and observe the execution of the current program. At the conclusion of program ex- ecution, 22RES will report on the following: * Use of Z-80-only instruction codes. If present, PROCESSOR=Z80 should be used. * Use of I/O instructions. If these are present, the program should be examined and the instructions modified or eliminated so as to be compatible with the PC hardware. * Presence of code likely to activate one of the V20 "bugs". If a message indicating this is present, a software emulation mode should be selected. Hardware-supported emulation (V20) results in the fastest execution speed for a program. 8080 software emulation (E8080) is approximately 4 times slower, with Z80 software emulation (Z80) about 6 times slower than V20/V30 supported hardware emulation. On PC-AT-class Page 7 machines, the software emulation modes compare favorably with a PC-XT class machine using a V20 processor. PROCESSOR may be abbreviated as PRO. BIND="filename" is an optional parameter to produce a "unitized" *.COM using the contents of "filename" as the image of the CP/M object. In this case, a ".COM" file will be produced that includes the pre-loader and the CP/M program file. Observe that since the BIND op- tion generates a file containing the CP/M object code, you must re-GENCOM this file each time the CP/M object is changed. Here are some examples of the GENCOM command: GENCOM DDT Builds a file, DDT.COM , containing the pre-loader only. If a V20 is present, its emulation capabilities will be used. Otherwise, 8080 software emulation will be performed. Standard DOS input and output will be performed. GENCOM WS KEY=WS DIS=ANSI Builds a file, WS.COM , containing the pre-loader only. If a V20 is present, its emulation facility will be used. Otherwise 8080 software emulation will be performed. A special WordStar keyboard mapping will be used; console output will emulate a standard ANSI terminal. GENCOM ZSID PRO=Z80 BIND=ZSID.CPM Builds a file, ZSID.COM , containing the pre-loader and the program file ZSID.CPM . Z80 software emulation will be performed and standard DOS input and output will be used. GENCOM MYPROG PRO=TEST Builds a file, MYPROG.COM , containing the pre-loader only. Z80 software emulation will be performed and a note will be made if any Z80-only instructions are used. In addition, any code likely to run afoul of V20 bugs will be noted, as well as usage of any I/O instructions. GENCOM Displays a summary of GENCOM command syntax. LOCATING CP/M PROGRAM FILES Page 8 It has been mentioned that GENCOM generates a "pre-loader" for a CP/M program in order to interface to 22RES. 22RES, however, needs to know where to find the program file itself. 22RES lo- cates program files the following way: (1) If the environment variable CPMPATH is defined, 22RES will search the drives and directories given by it. The syntax for describing a search path with CPMPATH is identical to that used for PATH ; namely, a list of directories or drive names, separated by semicolons. (2) In the absence of any other indication, 22RES searches for a program according to the PATH environment vari- able specification. That is, 22RES will look for a program in the same places and in the same order as the DOS command processor. (3) If neither a search of PATH nor CPMPATH results in the requested file being found, the current directory is searched for the file. As an example, suppose all of our system's CP/M program files are located in the subdirectory \USR\CPM22 . We could indicate this to 22RES by means of the following DOS statement: SET CPMPATH=\USR\CPM22 Observe that, since DOS is responsible for loading the "COM" pre-loader files, only the PATH environment variable has any ef- fect on the main DOS search path. In other words, CPMPATH only has relevance when "CPM" program files are involved. A SAMPLE 22NICE INSTALLATION Suppose you'd like to run some of the programs from your Osborne I on your PC-XT clone. You haven't installed a V20 chip in place of the 8088 processor yet, but you're considering it. You al- ready have the 22NICE files downloaded from your local BBS. Let's look at what's needed to get your system going with 22NICE . 1. ADD THE 22RES LINE TO THE DOS CONFIG.SYS FILE . Using your favorite text editor, you add this line to the CONFIG.SYS file in the root directory of the boot disk unit; in this case, the fixed disk: DEVICE=22RES.SYS You also make sure that 22RES.SYS is located in the root directory. Page 9 2. DETERMINE WHERE CP/M PROGRAM FILES WILL BE KEPT . As mentioned earlier, any CP/M ".COM" program files need to have the extension part of their file names changed to ".CPM". Also note that 22RES will need to know where these files are located. On your fixed disk, you've decided to keep them in a directory called "CPM22" , so you need to add the following line to our AUTOEXEC.BAT file: SET CPMPATH=C:\CPM22 to inform 22RES where to find the CP/M program files. You also make the appropriate directory with the following DOS command: MKDIR C:\CPM22 3. RE-BOOT THE COMPUTER . You want to check out what you've done so far, so you press the Ctrl, Alt and Del keys on the keyboard to reboot DOS. If all goes well, you'll see a 22NICE registration form come up (which we bypass by pressing the space bar) and a message that 22NICE is installed. If any errors show up during the system initialization process, you should correct them at this point. 4. COPY THE CP/M FILES TO DOS . Suppose that you'd like to run two programs from our Os- borne: PWP.COM , a proprietary word processing package. This requires Televideo 920-type console display capabilities. You'd also like the keypad to function in WordStar mode. You don't require the Z80 instruc- tion set, however. MLP.COM , a mailing list program. This requires no spe- cial console I/O, but does make use of the Z80 instruc- tion set. You can copy PWP from your Osborne diskette in the PC's A: drive with the following 22DISK CTOD command: CTOD A:PWP.COM C:\CPM22 Or, if you already have PWP.COM in the CPM22 directory, you need to rename it to have a "CPM" extension: REN PWP.COM PWP.CPM Page 10 In the same manner, MLP can be copied from the same diskette with this command: CTOD A:MLP.COM C:\CPM22 After the copying or renaming is finished, you check the CPM22 directory and find that two files, PWP.CPM and MLP.CPM have been placed there by CTOD. 5. RUN GENCOM FOR THE PROGRAM FILES . You need to generate two pre-loader files which contain in- formation for 22RES concerning our programs. You use GENCOM to generate the files: GENCOM PWP DIS=TVI920 KEY=WS GENCOM MLP PRO=Z80 After running GENCOM, you discover that two short (about 640 bytes) files have been created: PWP.COM and MLP.COM . These are the files that DOS will execute when you call for PWP or MLP. 6. COPY ANY NEEDED DATA FILES . If you require any data files, you can use CTOD to copy them also. For example, suppose a customer address file for your mailing list program is needed. You copy it using CTOD: CTOD A:CUSTLIST.DAT 7. RUN THE PROGRAMS . To run PWP, just type PWP the same way you'd have entered it on your Osborne. After this, PWP and MLP will behave as ordinary DOS programs. You may re-specify the operating parameters of PWP by running GENCOM again. Remember that the DOS file PWP.COM contains the name of the CP/M file PWP.CPM . If you rename PWP.COM , it will still cause PWP.CPM to be executed. USE OF CP/M SUBMIT AND XSUB Page 11 If you have "batch" files which operated with CP/M 2.2's SUBMIT facility, you'll need to alter them to use DOS's batch file capability. Usually this will entail no more than the following: 1. Change the file name extension from "SUB" to "BAT". This is done with the DOS RENAME command. 2. Edit the file, changing all parameter references from $1, $2, etc. to %1, %2 and so on. 3. Instead of using SUBMIT "filename" to invoke the file, just use "filename" as a command. A special problem arises when XSUB is used in a batch file. DOS has no direct analogue of the XSUB function, but it may be simu- lated by means of input file redirection. Consider the following sample batch file: XSUB SAMPLE $1 line 1 for SAMPLE line 2 for SAMPLE ^Z This file could be rearranged to yield the same results under DOS: echo line 1 for SAMPLE"x echo line 2 for SAMPLE""x SAMPLE %1"x DELETE X Of course this is only one possibility; you may wish to make use of the "pipe" facility of DOS, if the input to your program comes from another program. USER NUMBER SUPPORT You may specify that CP/M user numbers used by some programs be converted to DOS subdirectory references. This is done by set- ting an environment variable of the form USERx to the directory name to be used for that user number. For example, suppose that all user number 13 references are to be converted to reference the directory C:\COMPANY3 . The following DOS command would accomplish this: SET USER13=C:\COMPANY3 Page 12 You can get a map of user number-directory correspondence by ex- ecuting the CUSERS command. The following is sample output from CUSERS: CUSER Copyright 1988, Sydex. All rights reserved. User 1 = \CPMFILE1 User 2 = A:\ User 3 = \DATA\DB Search path: C:\CPMFILES, then .;C:\SYS;C:\USR;C:\BIN Note that CUSER also displays the search path used by 22RES. A command corresponding to the USER command of CP/M is not provided in 22NICE - the DOS CHDIR command accomplishes the same purpose. If a USER command is required, consider the following DOS batch file: REM USER COMMAND IF %1==1 CHDIR %USER1% IF %1==2 CHDIR %USER2% IF %1==3 CHDIR %USER3% ...and so on... which works for DOS 3.1 and later. Observe that User 0 is always the current directory. A defini- tion of the environment variable USER0 will be ignored by 22NICE . SAVING MEMORY IMAGES - THE CSAVE COMMAND DOS provides more-than-adequate substitutes for most CP/M resi- dent commands, with the exception of SAVE . 22NICE provides a command, CSAVE, with the same syntax and operation as CP/M SAVE: CSAVE "count" "filename" As in CP/M, "count" is the number of 256-byte blocks to be writ- ten to "filename". Observe that CSAVE will also change the file extension to "CPM" when one of "COM" is specified. MISCELLANEOUS TOPICS This section deals with some of the more specialized features of 22NICE and reflects Sydex's own experience with using 22NICE . Page 13 Accessing I/O Ports 22NICE supports access to 8-bit I/O port numbers via the 8080 IN and OUT instructions. Occasionally it may be neces- sary to access a PC I/O port greater than 255. This can be done by means of the 8080 "RST 3" instructions. To read a byte from an I/O port, code the following - LXI D,port number RST 3 The contents of the I/O port will be returned in the 8080's A register. To write a byte to an I/O port, code the following - LXI D,port number RST 4 The contents of the 8080 A register will be written to the specified port. Accessing PC Memory During emulation, a program's memory access is limited to the 64K addressing range of the 8080. Should it become necessary to inspect the contents of a memory location out- side of this range, the following "RST 5" call can be used: LXI D,segment LXI H,offset RST 5 The contents of the memory location at the specified segment and offset will be returned in the 8080 A register. IOBYTE Support The CP/M 2.2 IOBYTE mappings are supported by 22NICE for the console, printer, punch and reader as described in the "CP/M 2.2 System Alteration Guide". All other mappings will result in a null device access; i.e., data output will be discarded, input will result in an end-of-file, and input status will always be "data unavailable". Page 14 The CP/M punch and reader devices are taken to be the DOS auxiliary device. Usually, this is a serial communications port, or in absence of a serial port, the null device. Physical Disk Addressing 22NICE contains an interface to disk read and write routines present in DOS. When a CP/M program requests a DPB (Disk Parameter Block) from 22NICE (BDOS function 31), one is sup- plied which defines a 36-sector track with the allocation block size and number of tracks varying according to the capacity of the disk being serviced. Note that DOS can describe drives much smaller (less than 1K) and much larger (32,000 K) than CP/M; 22RES attempts to build a DPB which best defines the disk in question. Utilities that directly write to a disk without making use of BDOS calls should be avoided, as the DOS structure for a disk is quite different from that assumed by CP/M. 22RES attempts to emulate the disk interface of CP/M. However, because of differences in implementation, disk sizes reported by STAT and similar programs should be con- sidered to be approximations only. Maximum Program Size 22RES has a very small BIOS area and only 6 bytes of BDOS with no CCP. This means that a CP/M program has about 63K of program memory available for use - more than on any "native" CP/M system. Disk Drive Reassignment A number of older CP/M 2.2 programs have diskette drive selections "hard-wired" into them. This can be an incon- venience, particularly if you use a hard disk system. Use of the DOS ASSIGN command will allow you to re-map the drive accesses made by CP/M programs. IN CLOSING Thank you for taking the time to consider Sydex. We hope that 22NICE does its job well and that it meets your needs. This product represents several months of work and research; if you have any suggestions on how it might be improved, please let us know. Page 15 OTHER SYDEX PRODUCTS SHAREWARE ANADISK - The compleat diskette utility. Nothing like it anywhere else; scan, edit, repair and copy just about any kind of diskette. $15.00 Shareware registration fee. TELEDISK - Turn any diskette into a compressed data file and vice-versa. Allows you to send and receive entire diskettes via modem. Great for those bootable game diskettes and for diskettes with subdirectories. Works with most "copy- protected" diskettes. $15.00 Shareware registration fee. COPYQM - Cheap diskette duplicator. Format, copy and verify multiple diskettes from a single master. Implements "smart" drive status determination, freeing the operator's hands from keyboard interaction. Handles all standard DOS formats including 3.5" 1.44M files. $15.00 Shareware registration fee. FORMATQM - Mass diskette formatter - format a box of dis- kettes at a single sitting. Implements "smart" drive status determination, freeing the operator's hands from keyboard interaction. Format a 360K diskette in 41 seconds. Sup- ports all standard DOS formats. $10.00 Shareware registra- tion fee. RETAIL SOFTWARE SIM-CGA 4.2 - Color Graphics Adapter simulation on monochrome (Hercules-compatible) graphics-equipped machines. Available from better software retailers and distributed by CSS, ABCO and American Software Distributors. SIM-EMS - Simulate Lotus/Intel/Microsoft Expanded Memory on PC-AT class machines. Conforms to EMS 3.2 specification. Distributed by CSS and ABCO. Page 16