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╔═══════════════════════════════════════════════════════════════╗ ║ ║ ║ Joan Riff's "Z80MU PROFESSIONAL" Z80 and CP/M 2.2 Emulator ║ ║ ║ ║ Copyright (C) 1989 Computerwise Consulting Services ║ ║ P.O. Box 813 ║ ║ McLean, VA 22101 ║ ║ (703) 450-7175 ║ ║ ║ ╚═══════════════════════════════════════════════════════════════╝ ╔═══════════════════════════════════════════════════════════════╗ ║ IMPORTANT NOTICE! Please read and understand the following... ║ ╚═══════════════════════════════════════════════════════════════╝ This is a fully-functional version of Joan Riff's "Z80MU PROFESSIONAL" Z80 and CP/M 2.2 Emulator, which allows you to run most CP/M 2.2 and/or Z80 software on the IBM PC. This is not "crippleware". No functions have been disabled. This is the complete product, an exact image of the same emulator that we use here at CCS to produce Z80 controller software on the PC. However, we *ARE NOT* giving it away. We have placed many packages into the public domain in the last five years, but this is not one of them. This package is being distributed as "shareware", which translates roughly into "Try it *BEFORE* you buy it". This does not mean "Use it, don't pay for it, and don't tell anybody". We are the owners of the copyright for this software and all associated files and documentation. As the owners, we are free to specify how the package may be distributed, who may use it, and under what conditions it may be used. Under federal copyright statutes, our word in this matter is law. So please pay attention. HOW IT MAY BE DISTRIBUTED ------------------------- This package may be transferred by you to others, but *ONLY* if you distribute the original ZIP (or ARC) file, and *ONLY* if what you distribute is unchanged. It may be posted to Bulletin Board Systems (BBSs), and may reside there indefinitely in its original ZIP (or ARC) format for others to find and download. WHO MAY USE IT -------------- This package may be used by any individual who abides by the restrictions which we place upon the package, which means in summary that - except for a 14-day trial period - THIS PRODUCT MAY BE USED ONLY BY THOSE WHO ARE IN POSSESSION OF A VALID LICENSE ISSUED BY COMPUTERWISE CONSULTING SERVICES. UNDER WHAT CONDITIONS MAY IT BE USED ------------------------------------ You have our permission to unpack the ZIP (or ARC) file, examine the files contained therein, and briefly evaluate the package. Once the ZIP (or ARC) file is unpacked, the components thereof may not be distributed to others in any form. Remember - only the original ZIP (or ARC) file may be distributed. By "briefly evaluate" we mean that you may try out the package for up to 14 days, in order to decide whether or not it's right for you. If you have CP/M software which you want to run on the PC, then 14 days is ample time for you to move that software to the PC, run it under Z80MU PROFESSIONAL, and see whether or not Z80MU PROFESSIONAL will do what you need done. If you don't think that this package is worth the registration price, then don't use it. Period. Not even to run the CP/M assembler ASM.COM, or to disassemble a Z80 ROM, or to run the CP/M version of WORDSTAR. Such use violates our copyright. If you like the package, then buy it. Period. With "shareware", you buy it by registering with us. HOW TO REGISTER --------------- The fee for registration is $150 per user of the package (not per system). Send your name, address, telephone number, and the registration fee to: Z80MU Registration Computerwise Consulting Services P.O. Box 813 McLean, VA 22101 This registration process notifies us that there is one more user of the package to be supported by us. We want to be sure that you are properly supported. So when we receive your registration fee, we send you: 1) A disk with the latest version of the software on it. Sad to say, there are folks who introduce viruses (and other bugs) into packages that they find on BBSs, and then send the corrupted versions on to other BBSs. We discovered this with our public domain versions of Z80MU, DIAGS, and others, which is the primary reason that we no longer place software into the public domain. So when you register, you get a copy of the package straight from us, which is guaranteed to be a "virgin" copy, and to be the very latest version of the software. 2) A printed manual. You really can't get the most out of this software until you read the manual. Sure we've made the program easy to use. But there's no substitute for being able to curl up with a good manual when you want to become really smart about a product. 3) A single-user license, which gives you legal permission to use this product. PERSONS WHO USE THIS PRODUCT WITHOUT HAVING SUCH A LICENSE IN THEIR POSSESSION ARE IN VIOLATION OF FEDERAL COPYRIGHT LAW, AND MAY BE SUBJECT TO CIVIL AND/OR CRIMINAL PROSECUTION. You also get entered into our database of supported users. When you call as a registered user of our software, then you have our undivided attention. Period. Our expensive telephone answering and routing system exists solely to support *YOU*, the user who keeps us in business. Lastly, by paying the registration fee you obtain our permission to use this software. If you don't pay the fee, you don't get our permission: this will not make your boss very happy (if you use this software at work), since his company is legally liable in federal court for copyright violations. Sure, you *COULD* keep the software for your own use without registering it - thus violating our copyright - and try to hide it from everybody. But what would you have gained? It must be a neat program, or else you would not want to use it at all (let alone illegally). So you've got access to the world's best operating system emulator, AND YOU CAN'T TELL ANYBODY! What's more, by your own admission (because you use it) we must have done a good job in writing the software. But you won't give us credit? Sorry, but we just can't imagine even a Software Scrooge being quite that sick in the spirit... BBS SYSOPS NOTE: If you make the original ZIP (or ARC) file of this package available on your system for others to download, then we might register you WITHOUT CHARGE. Just follow the registration process, but instead of including a registration fee include the phone number of your BBS, and a userid and password for Joan Riff to use to dial in to your system. When we dial in and verify the presence of the original ZIP (or ARC) file on your system, then we will send you a license to use this package - with our compliments! Unfortunately, this offer must be limited to the first 100 respondents. ╔═════════════════════════════════════════════════════════════════════════╗ ║ Background: Why Z80MU PROFESSIONAL? ║ ╚═════════════════════════════════════════════════════════════════════════╝ We are the folks who created Z80MU version 3.10, which was placed in the public domain in 1986, and was featured in the October 1986 issue of BYTE magazine as one of seven "Public Domain Powerhouses of 1986". According to our estimates (which are admittedly contestable due to the impossibility of accurately tracking public domain distribution), that version of Z80MU has rapidly become the most widely-used CP/M and Z80 emulator of any type (public domain, shareware, or commercial) in the world, due mainly to the uncanny accuracy of Z80MU's emulation of CP/M and of the Z80 chip. Since 1986, we have completely rewritten Z80MU 3.10 in order to produce Z80MU PROFESSIONAL. This new package greatly increases the productivity of folks (like us) who deal with Z80 object code all day long, and - believe it or not - emulates CP/M much more accurately than even that reliable old workhorse Z80MU 3.10 did. Unlike Z80MU 3.10, Z80MU PROFESSIONAL is not being placed into the public domain. It is sold as a commercial product. Yes, it's nice that out of the goodness of our hearts we placed Z80MU 3.10 in the public domain. And we're truly happy that so many folks have said flattering things about Z80MU 3.10. But there are aspects to public domain distribution which we overlooked back in 1986: 1) CORRUPTION: There are many copies of Z80MU 3.10 floating around various bulletin boards - and even being sold by so-called Public Domain software houses - which have been corrupted so that the 100-page manual or the executable file are not the same that they were when we released them. Some of this corruption seems to be inadvertant. Some seems to be deliberate. But since there are so many copies out there, we have lost all control over the package. When we come across a bad copy, we try to destroy it and replace it with a good copy. But we can't possibly track them all down, due to the nature of public domain distribution. And keeping long-distance bulletin boards up to date leads straight into... 2) WE LOST OUR SHIRTS: In theory, you place something in the public domain as a favor. People ought not to expect constant support for a public domain product. Just because we're decent folks and can emphasize with the poor end user, we have provided many long hours of support to users of Z80MU 3.10 at no charge. But this costs us. And every time that Computer Shopper or some other irresponsible publication reviews Z80MU 3.10 and says (without our permission) something like "CCS will send you a copy of this excellent program for FREE", we are inundated with calls and letters from readers who want as much as they can get for free. Due to the sheer volume of incoming requests, many must go unanswered. Some readers get irate, like the [few] who have said "I paid $3 for Z80MU from Such-and-Such Software, and I expect support, buddy!", and the one Good American who demanded "If you weren't gonna support the thing, why the h___ did you put it in the public domain!?" We lose because of the ill will created by such encounters. We lose because the manhours spent supporting users of Z80MU 3.10 are manhours that we aren't getting paid for. So we're still paying for that perhaps ill-advised but well-meaning decision back in 1986 to release Z80MU 3.10 to the public domain. We may learn slow, but we learn well. So we are offering Z80MU PROFESSIONAL for sale. We *WILL NOT* release it to the public domain. But we *WILL* support each and every purchaser, and we *WILL* guarantee that any copy which you get direct from us is free of corruption and viruses. ╔═════════════════════════════════════════════════════════════════════════╗ ║ Files on the Z80MU PROFESSIONAL Distribution Disk ║ ╚═════════════════════════════════════════════════════════════════════════╝ Filename Size Date ═════════════ ═════ ════════════ AUTOEXEC.Z80 315 2 Feb 1989 DDT.SYM 589 19 Sep 1988 SETTINGS.COM 1152 14 Jan 1989 TEST.COM 4736 20 Aug 1989 TEST.SYM 6516 20 Aug 1989 Z80MU.EXE 113652 22 Aug 1989 Z80MUDMP.COM 1400 23 Sep 1988 ZCONVERT.EXE 8948 21 Feb 1989 AUTOEXEC.Z80 This is a sample AUTOEXEC.Z80 file. If such a file is present in the current directory when the Emulator begins execution, then the Emulator will automatically read and execute all commands which are present on this file. Feel free to change this file to suit your own preferences, or to delete it entirely. DDT.SYM Chapter 7 of the Z80 PROFESSIONAL manual describes the operation of the Disassembler. At the end of the chapter (see page 7-8) is an example which applies a Symbol Table to Digital Research's DDT.COM program. This file is the Symbol Table which is shown in the text. We have included it here so that you don't have to type it in from the sample shown in the manual. Just read this file into the Emulator via "SUBMIT DDT.SYM" where the text says to enter "the list of commands shown above". SETTINGS.COM This is a CP/M program which displays some of the current Emulator settings. You should copy this file to whatever directory holds your CP/M utility programs, as defined by the "CPMPATH" environment variable. Don't try running this file directly from DOS! It must be run under the Emulator! TEST.COM This is a sample CP/M program which simply demonstrates that the Emulator does, in fact, run CP/M software. In addition, this one automatically sets H19 terminal emulation mode, and recognizes PC extended keypresses. Don't try running this file directly from DOS! It must be run under the Emulator! TEST.SYM This is the Symbol Table file for TEST.COM. This file is useful if you're interested in learning about Z80MU's RESOURCE facility. The symbols in this file can turn a disassembly of the object code in TEST.COM into something very close to the original source code. To demonstrate this, issue the following Z80MU commands: coldboot read test.com dissam 100 Note: This disassembly will show little more than raw opcodes, because Z80MU has no symbol information to work with. submit test.sym Note: This reads in the symbol information. dissam 100 Note: This time, the disassembly contains enough symbol information to produce original source code. Z80MU.EXE This is the Emulator itself. Copy this file to one of the hard disk directories specified by your "PATH" environment variable, so that it is available at the DOS prompt no matter where you are on your hard disk. Z80MUDMP.COM This is a DOS program which handles the printing of the screen to the printer. It replaces the standard IBM PC ROM BIOS print screen routine. Many of the Emulator screens contain PC graphic characters. When the IBM PC ROM BIOS print-screen routine prints these characters, it sends odd escape codes to the printer which may thoroughly confuse it. This program - Z80MUDMP.COM - knows how to translate these odd characters into the proper codes for the printer. This yields accurate screen dumps without producing garbage on the printer. This program may be used with or without the Emulator. It is a stand-alone utility which should be invoked when your system first boots up, so you should copy this file to a hard disk directory which is available at system boot time (we recommend that you copy it to the root directory of drive C:). When the program is invoked, it accepts one command-line parameter. This tells the program whether your printer can handle IBM PC graphic characters: Z80MUDMP I installs the program, and tells it to use the IBM PC character set. Z80MUDMP A installs the program, and tells it to use the ASCII character set. PC graphic characters which are on the screen will be translated into near ASCII equivalents. ZCONVERT.EXE This is a DOS program which converts an old-style symbol table control file as created by version 3.10 of Z80MU into a new-style symbol table which may be used as a submit file with Z80MU PROFESSIONAL. The old-style control file is read from standard input, and the new-style table is written to standard output, so the proper way to use this program is by typing the following at the DOS prompt: zconvert <oldfile >newfile [Note: Substitute your own filenames for "oldfile" and "newfile" in the above example.] You may then input the new file into Z80MU PROFESSIONAL via the Z80MU command: SUBMIT newfile The conversion isn't perfect, due to differing limits imposed by the two versions of Z80MU. Labels may be truncated, and so on. Just load the new file into Z80MU PROFESSIONAL and clean it up with the full-screen disassembler. ╔═════════════════════════════════════════════════════════════════════════╗ ║ Running Z80MU PROFESSIONAL ║ ╚═════════════════════════════════════════════════════════════════════════╝ The "shareware" version of Z80MU PROFESSIONAL does not include any sort of manual. When you register your copy, you will receive a manual. In the meantime, the following should be sufficient to get you up and running: 1) To install Z80MU, simply copy all of the distribution files into one directory on your hard disk (or to a work floppy). Likewise, copy to the same directory any of your CP/M programs which you will want to run. 2) You start Z80MU running just by typing in "Z80MU" at the DOS prompt. Once Z80MU begins execution, it displays its copyright screen. Press {Return} to acknowledge that you have read the screen. For all intents and purposes, you are now running CP/M on your PC. 3) Z80MU PROFESSIONAL (like all of our products) contains extensive online documentation. At Z80MU's CP/M prompt, just type "HELP". You will be presented with screen after screen of help, with one screen for each and every command which is processed by Z80MU. You may page through these HELP screens with the {PgUp} and {PgDn} keys. For more details on the use of HELP, type "HELP HELP" at Z80MU's prompt. 4) You quit Z80MU by typing "QUIT" at Z80MU's prompt. This brings you back to DOS. ╔═════════════════════════════════════════════════════════════════════════╗ ║ Changes for Z80MU PROFESSIONAL version 5.2a ║ ╚═════════════════════════════════════════════════════════════════════════╝ 1) Distribution was changed from advertising to the "shareware" concept. No changes were made to the source code. The DEMO version of Z80MU PROFESSIONAL is now outdated. ╔═════════════════════════════════════════════════════════════════════════╗ ║ Changes for Z80MU PROFESSIONAL version 5.2 ║ ╚═════════════════════════════════════════════════════════════════════════╝ 1) The video routines were tweaked to provide faster support for CGA's, because CGA support was brutally sacrified at the altar of blinding performance for everybody else. Now it's reasonable. 2) The handling of direct port I/O (via SET_IOBASE) has changed slightly. When the Z80 CPU emulator encounters a Z80 IN or OUT instruction, the logic is now as follows: a) Add the 8-bit Z80 I/O address to the current I/O BASE as set by the last SET_IOBASE command, thus yielding a 16-bit PC I/O address. b) Handle the operation according to the resulting 16-bit PC I/O address: FF00 - FFFF: No I/O is performed, although any auto-increment etc is accomplished. Only the actual I/O is ignored. But the program continues to run. So if you want to run a Z80 program which you know does direct I/O but which you don't want to have aborted, use "SET_IOBASE FF00". 0400 - EFFF: The program is aborted. So if you want to trap any programs which you suspect might do direct I/O, use "SET_IOBASE 400". 0000 - 03FF: The I/O is performed to the resulting 16-bit PC I/O address. 3) A "PATCH" command has been added, for those times when you just have to patch CP/M memory from a SUBMIT file. 4) A "GO" command has been added to continue execution of an interrupted program, for those times when you just don't want to have to get into the debugger just to issue an {Alt-G} (for "Go") command. If you've started a program, for example, and discovered that the program requires a different terminal type, then just interrupt the program with ^BREAK, issue the right "SET_TERM" command, and then use this new "GO" command to resume execution where it left off. 5) The labels generated by the "SYMGEN" command have been changed slightly. Instead of being "AUTO99999" (where 99999 starts at zero and increments with each generated label), they are formatted as "AUTO_xxxx", where "xxxx" is the address of the label. This makes it easier during the analysis phase to see just what an auto-generated label refers to. Our apologies to those who will submit the generated source to an assembler which does not allow the underscore character in labels. All things considered, we thought that this method was the best for all concerned. Just use your editor to change the "_" characters to something else if you must... 6) RST 7 instructions are no longer used for breakpoints. Instead, we have gone back to the version 3.10 method of using HALT opcodes for the breakpoints. This allows you to use the debugger to trap code which isn't for CP/M (such as ROM-based disk controller code), or to set breakpoints in CP/M debuggers like DDT which use the RST 7 for their own use. One side effect of this is that you will be using the emulated Z80 CPU as long as you are in the debugger - even if the 8080 CPU (using the NEC V20 chip) had been in effect when you entered the debugger. So if you issue the "Go" command via {Alt-G} in the debugger, the program will be executed as Z80 opcodes, via the software Z80 emulator. When you exit the debugger, you will be switched back to the proper emulated CPU. Note, however, that RST instructions *ARE* still used for various CP/M-related operations like BIOS and BDOS calls. Since such calls only make sense in a CP/M application, this should be no problem. 7) Under certain circumstances the Z80MU prompt would appear farther up the screen than it should. This occurred whenever you sent output to the CON device (i.e. = "SYMLIST" without a filename, or "RESOURCE 100 1ff CON"). This has been fixed. ╔═════════════════════════════════════════════════════════════════════════╗ ║ Changes for Z80MU PROFESSIONAL version 5.1 ║ ╚═════════════════════════════════════════════════════════════════════════╝ NOTE: A new manual was produced for version 5.1, so changes listed for version 5.1 or for prior versions are reflected in the manual. Changes for later versions are not in the manual. Any information here which conflicts with information in the manual takes precedence over the information in the manual. 1) The SET_MASK command has been added to allow masking of output characters to 7 bits. 2) Various commands (CD, CHDIR, MD, MKDIR, RD, RMDIR, CLS) which used to be passed to DOS and handled by COMMAND.COM are now handled internally by the Emulator. This speeds up the processing of these much-used commands. 3) The video support routines have been rewritten. Speed with EGA and VGA displays has been improved, but CGA displays which need to have snow eliminated by software will be a little slower than before. 4) The printed Step output obtained by {Alt-L} in DEBUG has been reformatted for easier scanning of voluminous output. In addition, any disassembled line with a PC value of 0005 has an asterisk at the left edge, to enable you to locate BDOS calls quickly. 5) The "WRITE" command used to generate a bad checksum on the last line of a HEX file in certain circumstances. This has been fixed. 6) Single-step mode used to execute two instructions upon return from a BIOS or BDOS call. This has been fixed so that it properly stops between instructions. 7) You may enter an Emulator command when you invoke Z80MU. When used like this, the Emulator will process this single command and then automatically exit back to DOS. 8) DOS reports that there are at least 5 drives on the system, even if you have fewer than 5. So Z80MU determines the number of drives by itself. This is more accurate. 9) Some confusion has resulted from the "Select Drive" BDOS emulation. At each Emulator prompt, the drive is reset to whichever drive was active before a CP/M program was run. During CP/M operation, drive select requests will be honored. So far, this is just the same as you had with CP/M. The confusion occurs when you interrupt a CP/M program with ^BREAK (which you never could do with a true CP/M system). The Emulator interrupts the CP/M program, then gives you its prompt. As part of this prompt, it switches back to the "right" default drive (just as the original DRI CCP used to do). If you then enter the debugger and continue the program, you will still be using the Emulator prompt's drive. This MAY OR MAY NOT be the drive which your CP/M program last selected. This MAY OR MAY NOT be the drive that you want to be the default one as you continue the CP/M program. 10) The CP/M BDOS emulation has been improved (again!). ╔═════════════════════════════════════════════════════════════════════════╗ ║ Changes for Z80MU PROFESSIONAL version 5.0 ║ ╚═════════════════════════════════════════════════════════════════════════╝ NOTE: This list details the most significant differences between the last public domain version - Z80MU 3.10 (the one featured in the October 1986 issue of BYTE magazine) - and the first version of the Z80MU PROFESSIONAL series (version 5.0). This list is by no means complete, because Z80MU PROFESSIONAL was a complete rewrite of the source code. There are innumerable differences not listed here which *WILL* make a difference in operation. Nevertheless, we feel that it is important to show some of the differences, so that owners of the public domain version (Z80MU 3.10) will know what the PROFESSIONAL version offers over the public domain version. NOTE: We will not disclose details here. We made that mistake when we wrote the definitive article on Z80 and CP/M emulation which appeared in the October 1986 issue of BYTE magazine. Soon after that article appeared, other emulators began incorporating our copyrighted code without our permission. Rather than litigate, we'll obtain justice by keeping Z80MU far and away the fastest and most accurate emulator of the Z80 and of CP/M for the IBM PC - and we *WON'T* tell them how we're doing it! 1) The user interface is interactive and lightning fast. We no longer use the very slow DOS input and output routines. On the negative side, this means that you can no longer use DOS I/O redirection when the program is run. On the positive side, this means that screen output is very fast, you have control over the colors used, and in general we can provide a much more productive environment. 2) You can recall and edit previous commands. 3) Interactive, full-screen help, disassembly, and debugging. This alone made the switch from DOS I/O worth it. You haven't lived until you have seen how fast and easy it is to create source code from object code using the disassembler, which includes: a) Full-screen, instant updates. Whenever you tell the Emulator something about the object code, the result appears instantly on the screen. In effect, you are looking at a living disassembly of the object code. b) Support for Z80 or 8080 mnemonics. And the full-screen debugger is likewise a joy to use: a) All Z80 registers (including the Stack) are always on the screen, and the first dozen or so source statements at the current PC are always accurately disassembled and on-screen. b) To change any register, you just move the cursor to that register's on-screen value and type in the new value. c) You may have up to 8 unconditional breakpoints active at once, and each can contain a pass count. When any of the 8 breakpoints are reached, execution stops and the debug screen instantly appears. d) You may also specify a Conditional Break, such as "Break when the PC is greater than F600", or "Break when the PC equals 0005 and the C register holds 1A". e) BDOS and PC History tracebacks have been carried forward from version 3.10. In addition, you can have instructions disassembled to the printer (with or without the current register values) as they are executed, and limit this activity to a range of CP/M addresses. This is just the thing for those tricky bugs which are hard to catch, when what you really need is a boxfull of paper containg a step-by-step disassembly of every single instruction which was executed... And the "HELP" command is a great improvement over the primitive list that was necessary when using DOS: a) Each command is explained in its own on-screen window. b) You may page forward or backward through these help windows, until you find what you want. Or you may ask for help with a specific command. 4) An optional CCP has been included, which is the functional equivalent of Digital Research's CCP. This allows those few CP/M programs which mistakenly assume the presence of a CCP to run under the Emulator. 5) The four most-needed terminals have been emulated: Televideo 950, VT52 (Heath/Zenith H-89), Osborne, and Kaypro. There is also a Raw emulation, which shows absolutely everything which is sent out. Needless to say, this emulation is much faster (and more accurate) than that provided with version 3.10. 6) The Emulator now supports the NEC V20 and V30 chips. This may seem exciting, and some users have purchased Z80MU PROFESSIONAL for this feature alone. But in all honesty we must warn you that NEC's implementation of the 8080 instruction set leaves much to be desired. Z80MU PROFESSIONAL uses the NEC chips as well and safely as they can be used, but these chips just aren't what they're cracked up to be. If you have some very safe and simple CP/M applications (like ASM, M80, L80, etc), then the use of these NEC chips with the Emulator will give very fast and safe performance. Just don't try to debug anything using the NEC chips, and above all don't feed them untested or buggy code. One wrong opcode and the NEC chips can easily hang your PC... 7) A "SUBMIT" command has been included, which emulates CP/M's own submit command, complete with parameter substitution. There is no provision for XSUB support, but our implementation has benefits (it doesn't go back to drive A for the submit file, for example) which make it more desirable for use on PC hard disks. 8) Some CP/M applications use "CP/M-specific" BIOS and BDOS calls to interrogate the disk environment. Under the public domain version of Z80MU these programs were simply aborted. Z80MU PROFESSIONAL allows you to decide whether to abort these programs or to feed them emulated CP/M information which is obtained from DOS. This alone allows many CP/M programs (TURBO PASCAL, for one popular example) to run under Z80MU PROFESSIONAL which could not run under the public domain version. 9) The accuracy of CP/M emulation has been improved. Z80MU version 3.10 was justly famous because it would run CP/M programs which other emulators could not. Well, we have greatly improved the emulation of CP/M even over the high standard created by version 3.10: a) The FCB fields change now in a way which is more closely aligned with the way that CP/M used to change them. b) During BDOS calls, the same Z80 registers are modified that CP/M modified, and in the same [sometimes silly] ways. c) Certain oddball CP/M calls (we won't say which ones) are handled by Z80MU PROFESSIONAL in a way identical to the way that CP/M handled them. Without giving too many details, we'll just say that this enables several hundred more CP/M programs to run under Z80MU PROFESSIONAL which would not run under the Z80MU version 3.10. d) The RLD opcode (the only one of the 600-odd Z80 opcodes which wasn't precisely emulated by Z80MU 3.10) has been fixed. 10) You may invoke your favorite PC editor from within Z80MU. This makes source code development seamless and easy. 11) You may cause Z80 "IN" and "OUT" instructions to be mapped to PC I/O addresses. Z80MU version 3.10 simply ignored these opcodes. 12) Here are a few of the new commands: SET_COLORS Define colors to be used SET_CPMECHO Control echo of CP/M screen output to the printer. SET_CPMLIST Define the PC device to be used as the CP/M "LIST" device. SET_CPMPUN Define the PC device to be used as the CP/M "PUN" device. SET_CPMRDR Define the PC device to be used as the CP/M "RDR" device. SET_CPMPATH Define a series of DOS directories to be searched by Z80MU when looking for a CP/M .COM file to be executed. SET_CPU Select the software Z80 emulated CPU, or the hardware (and fast) 8080 CPU made available by the NEC V20 and V30 chips. SET_EDITOR Define your favorite PC editor to be used within Z80MU. SET_FAKE Control the result of hardware-specific BIOS and BDOS calls (for example, to interrogate the disk parameters). SET_IOBASE Control the execution of Z80 IN and OUT instructions. SET_KEY Load a keyboard macro, to be played back when the associated key is pressed. SET_MASK Control the dubious CP/M practice of masking output characters to 7 bits. SET_SNOW Control the handling of "snow" on cheap IBM CGA video screens. SET_SOURCE Choose Z80 or 8080 mnemonics for disassembly. SET_TERM Select one of the builtin terminal emulations. SET_VARS Choose whether or not to interpret "$" characters in submit files as a parameter substitution leadin. TYPE Display one or more files in full-screen mode, pausing between screens. 13) An executing CP/M program may call Z80MU to obtain certain PC services (like controlling a serial port), and set or inquire about various Z80MU settings. So if you've got a CP/M accounting package which is set up for an H-19 terminal, for example, you can have that program automatically tell Z80MU to select H-19 emulation when it starts executing. Or if you are running a CP/M communications program, then that program can set Z80MU's I/O Base address so that it can access the PC's communications port directly via IN and OUT instructions.