**************************************************************************** * * * Documentation for CPCEMU (v0.8) - the CPC-Emulator for the PC * * * **************************************************************************** This is the english documentation for CPCEMU , for the german one consult CPCEMU_G.DOC. If you have questions or suggestions, write to Marco Vieth Auf dem Uekern 4 33165 Lichtenau (Germany) Or by e-mail : ali@uni-paderborn.de 1. IMPORTANT : ============== CPCEMU is Copyright 1993 by Marco Vieth, Auf dem Uekern 4, 33165 Lichtenau, Germany. Telephone: (...) 05292/1366 Internet address: ali@uni-paderborn.de This document and the files listed herein may be freely copied without charge, provided copyright notices are left intact. All software and documentation is provided "as is" without warranty of any kind. Although this program is freeware, I would certainly accept any sort of support, financial or ideal. 2. INTRODUCTION: ================ 2.1 For what purpose is an emulator ? -------------------------------------- There was (and is) much discussion about speed augmentation of older computers, p.ex. by replacing a slow CPU by a faster one, but mostly this is impossible (maybe caused by timing- problems). So why don't we take a much more powerful system as platform for running an emulation ? With progress in developement of new computer systems our old one is automatically improved, not only in speed, also concerning ergonomy (p.ex. 70 Hz screen, comfortable keyboard) and other advantages (p.ex. a hard-disc). Besides, it is a great pity not to be able to use your self- written programs on the new computer any more. Some years ago, I thought of an EPROM-simulator for testing EPROM-code in RAM. This is no problem with this emulator. It is at least fascinating to see old programs running on a total different computer. This all (and much more) offers you an emulator like CPCEMU. 2.2 What is a CPC ? -------------------- To keep it short: The AMSTRAD-CPC (Colour Personal Computer) has an 8 bit design with Z80A CPU, 3" disc drive, the operating systems AMSDOS (sometimes called as Advanced MSDOS, but it is rather AMSTRAD DOS), CP/M 2.2 and CP/M Plus. A powerful BASIC is implemented, with wich you can utilize most hardware qualities. For more information consult appendix "Information about the CPC" (A1.6). 2.3 What is CPCEMU ? --------------------- CPCEMU is the first emulator of the CPC computers you can take seriously. On a 386/33, the emulation is nearly as fast as the original, provided that you use little banking. CPCEMU is written in C and assembler, using Borland 3.1 (with 80386 code) and TASM. 3. REQUIREMENTS FOR CPCEMU : ============================= 3.1 Hard- and software requirements : ------------------------------------- - PC (at least a 386, as usual no limits to more) - VGA graphics - MSDOS (DRDOS hardly supposed) or - OS/2 2.x dos-box 3.2 Files which comprise the CPCEMU package : ---------------------------------------------- CPCEMU.CFG configuration-file (6.4) CPCEMU_E.DOC this file CPCEMU_G.DOC german documentation CPCEMU.EXE the executable (4.1) CPCPD1.DSK example-disk with PD-programs (6.2) CPCREAD.C source to CPCREAD.EXE CPCREAD.EXE programm for reading CPC-disks (6.2) CPMDISKS.DEF file with CPC-format-definitions for 22DISK (4.2.1) INSTALL.BAT installation program (4.1) PARALLEL.PAS transfer program for a parallel interface (4.2.2) README_E.DOC englisch README README_G.DOC german README ROMGET.ASC CPC-BASIC programm to save the ROMs (4.2.1) Z80CPC.ROM the "Need-ROM" (4.3) Z80DISK.ROM the program "Copymate" (not used) (Replace this ROMs by the original ones.) 4. INSTALLATION : ================= 4.1 Installation of CPCEMU : ----------------------------- Maybe you have done it already : Simply copy the archive CPCEMUxx.xxx into a directory of your hard-disc and decompress it. After that, use INSTALL.BAT, which creates the three subdirectories ROM, TAPE, DISC with the necessary files in it, where CPCEMU looks for ROM-images, "tape"-files and disc-images. Now you can start CPCEMU.EXE, but wait ... 4.2 How to get a ROM ? ----------------------- Problem : --------- The original CPC-ROMs are NOT enclosed ! Unfortunately, AMSTRAD has not allowed me to include them. For more information look at appendix "Letter from AMSTRAD" (A1.7). So you are forced to get the ROMs from somewhere else. In the following some possibilities : 4.2.1 If you have a CPC with 5.25" or 3.5" disc-drive : -------------------------------------------------------- With the 22DISK-utility by SYDEX you are able to read and write user-defined formats. I have included a specification for the CPC-formats. Simply copy the file ROMGET.ASC (a program to save the CPC-ROMs) onto a CPC-disc, run to your CPC and run the program. The ROMs OS, BASIC and AMSDOS are saved automatically (if present). Back on the PC, copy them into the directory .\ROM . If you own other ROMs, you can also copy them, after a small modification of ROMGET.ASC . Besides, you can "rescue" all your CPC-programs in this way. 4.2.2 With a parallel interface : ---------------------------------- After you have constructed a special centronics-cable and joined CPC and PC together, you can use the transfer-program written by Gilles Molinari. In the file PARALLEL.PAS you can find the two pascal-sources getfile.pas and sendfile.pas . 4.2.3 With a serial interface : -------------------------------- I think, it is as easy as the other possibilities, but I have not tried it. 4.2.4 Nothing of the kind : ---------------------------- Well, what can you do to enjoy a CPC ? - Type the ROM in your computer, maybe from a CPC-ROM-listing. - Write your own small operating system (that's only for professionals, I think, but I would be glad to receive a copy) - Write an advertisement in a computer-magazine with the following writing: "Who can copy me the CPC-ROM ?" ( In a special magazine, someone tries this already the second time, it seems, he didn't succeed yet. Why not ? ) - Ask AMSTRAD for the ROMs (maybe you've more success) But I cannot recommend this really. Be inventive ... ... and use the "Need-Rom" so long. 4.3 The "Need - ROM" : --------------------- For people suffering want (those without the CPC-ROMs), I have included a so-called "Need-ROM". It is located in the .\ROM-directory after installation and is used automatically, if no other ROMs are present under the same name. It contains only a program, which is total independend from the original ROMs (except for thr character-set). It is certainly not a satisfactory replacement. 5. THE SOFTWARE - CPC : ====================== 5.1 The first time : --------------------- Congratulations, you have mastered the biggest hurdle before using the emulator ingeniously. (Therefore you have copied the CPC-ROMs into the .\ROM - directory.) Execute CPCEMU.EXE, the configuration is loaded, the memory is initialized and -- fasten your seat-belts -- the software- CPC starts ... (To get back to reality, consult appendix "Command line parameters" (A1.1).) The CPC-opening-screen appears and you can do all you know from a real CPC. F10 interrupts the emulation (you get into the debug-menu), 'r' continues and 'q' quits. Consult appendix "The Debug-Menu" (A1.2). However, you must consider some features ... 6. FEATURES : ============= 6.1 The Keyboard : ------------------- Maybe you have already noticed that some keys react in a different way you have expected them to do. The supposed output on the screen differs from the lettering on the key you have pressed. The reason is that the CPC-keyboard-layout is physically mapped to that of the PC. This enables all key-combinations. If necessary, you must "try and error" with the motto "searching and finding". There are really all CPC-keys located somewhere (even one more, the "secret key"). 6.1.1 Special Keys : --------------------- - ALT, ALTgr : COPY - F1 - F12 : special functions, in detail : F1 : Help (possibly this text appears) F2 : toggles between CPC-screen (standard view) and message-screen (that one with a red border). On the latter some messages appear, among other things the cassette - catalogue. F3 : Insert a disk. A file from DISC_PATH is displayed and you can select it with 'A' or 'B' Ret for drive A or B. (Not very comfortable.) Please don't use this, if the disc is currently in use. F4 - F7 : reserved for future usages F8 : hard-reset (like reset-button for CPC) (use this, if CTRL/SHIFT/ESC hangs) F9 : reserved for future usage F10 : debug-menu (look at appendix "The debug-menu" (A1.2) ) F11 - F12: reserved for future usages - At this point, you will maybe ask, where to find the CPC - function-keys. Try the Keypad : With 'Num-Lock on', the keypad represents the function-keys of the CPC, otherwise the joystick. - The joystick : In addition to the keypad you can use an analog PC-joystick. Include "USE_JOYSTICK = YES" in the configuration-file (see below). Then you can use a joystick, if one is present. Note, that you can always use the "keypad-joystick". ( Unfortunately, my current joystick-routine is too slow, so you can only use the fire-buttons .) - The PAUSE-Key holds the PC until it is pressed again. 6.2 The Disc-Drive : --------------------- Disc-accesses managed by the FDC (Floppy Disc Controller) are redirected to a file specified in the configuration-file (see below : DISC_PATH + DRV_A respectively DRV_B). By using the program CPCREAD you can create such files from CPC-discs yourself. The file CPCPD1.DSK contains some example PD-programs. Look at appendix "Structure of Disc-Images" (A1.4). 6.3 The Tape : --------------- After the '|TAPE'-command, or if you don't own an AMSDOS-ROM, the "tape" is addressed. Tape-access is transformed into file- access in the directory TAPE_PATH (see configuration-file). By the way, the CATalogue appears on the message-screen (use F2 to toggle view). Non-ASCII files have included a preceding AMSDOS-header. Look at appendix "Structure of the AMSDOS-header" (A1.5). This bypass is realized by a ROM-modification, which is described in appendix "Function of the ROM-bypass" (A1.3). At this point you only need to know, that for cassette-usage this bypass must be enabled by the entry 'TAPE_BYPASS = YES' in the configuration-file ... 6.4 The Configuration - File : ------------------------------- Now the mystic configuration-file is described, but it is not mystic at all. In general : ------------ The configuration - file CPCEMU.CFG should be located in the same directory as CPCEMU.EXE . Comments are introduced by a semicolon ';', the rest of the line is ignored. Blanks, tabs, newlines and ';' are delimiters, they can be used between identifiers and values as many as you like. Many of the definitions have the syntactical form {T} '=' {T} {T} {T} is a sequence of at least one delimiter. Example : 'ROM_PATH = .\ROM' Not allowed is 'ROM_PATH=.\ROM' because of missing delimiters. If you don't want to (re-)define an identifier, make a comment by writing a ';' in front of it; not allowed is 'ROM_PATH = ' . The following constructs are used sometimes : can be given decimal or hexadecimal (with 0x).
may have a length up to 60 characters and up to 20 characters. Valid identifiers : ------------------- The values in brackets are default-values, if the referred identifier is not redefined. SHOW_CONFIG = {YES,NO} (YES) To suppress the configuration-message after starting the emulation. If some errors occured during startup, the configuration is always displayed. ROM_PATH =
(.\ROM) Sets the path to ROM-images. (See also identifier ROM_BLOCKS.) TAPE_PATH =
(.\TAPE) Sets the path to "tape"-files. (Also used in debug-menu during load, save; look at appendix "The Debug-Menu" (A1.2).) DISC_PATH =
(.\DISC) Sets the path to disc-images. (See also ident. DRV_A, DRV_B.) DRV_A = (DISC1.DSK) The disc actually inserted in drive A (a disc-image file in the DISC_PATH - directory). DRV_B = () Same as DRV_A, but for drive B. PRINTER = (PRINTER.PRN) A file in TAPE_PATH for lineprinter output. It is created at every emulation-start. TAPE_BYPASS = {YES,NO} (YES) Enables (or disables) the ROM-bypass of the tape-vectors, if a known ROM from a CPC 464/664/6128 is found. This bypass is necassary, if you want to use tape - files. Look at "The Tape" (6.3) and appendix "Function of the ROM-bypass" (A1.3). DISC_BYPASS = {YES,NO} (NO) Enables (or disables) the AMSDOS-ROM-bypass to suppress patching of tape-vectors by the AMSDOS-ROM. (So the tape-vectors are still pointing to tape, although the AMSDOS-ROM is initialized.) This is necessary, if you want continue loading from tape after a disc-reset, but without giving the '|TAPE'-command first. (It is done by 'poke &CCF2,&18 : poke &CCF3,&05' in AMSDOS-ROM.) Sector-instructions are not affected, they always address the disc. DISC_SPEEDUP = {YES,NO} (YES) Enables (or disables) a AMSDOS-ROM modification, which minimizes the motor waiting times to render a faster disc- access. (The things are managed by DOS, so we needn't the delay loops.) (The following bytes are modified in AMSDOS-ROM : poke &C5D4,&01 :'motor load-time poke &C5D8,&01 :'format trk-time poke &C5D9,&01 :'short wait poke &C5DA,&01 :'short wait poke &C602,&01 :'only 1 retry on error poke &C784,&01 :'fast seek poke &C7E2,&01 :'fast seek ) USE_JOYSTICK = {YES,NO} (YES) Enables (or disables) a PC-joystick, if present. You can always use the "keypad-joystick". VSYNC_CT = (1) Sets the count, how often the PIO-port B must be asked, until the vsync-bit toggles. In reality, this bit is only set during vertical frame-fly. Possible values range from 1 to 255. GENINT = (300) Sets the frequency of interrupt gereration (in Hz). In a CPC it is always 300 Hz. On slow computers, this value may be decreased to 100 (and SCR_UPD_CT to 2). Possible values are 18 Hz to ca. 600 Hz. SCR_UPD_CT = (6) Sets the screen-update counter. Every interrupts the screen is updated, if necessary. With GENINT = 300 and SCR_UPD_CT = 6, the screen is updated 50 times per second. (Valid values: 1-255). PORT_B = (0x3F) Sets the input-value "lying" at port B of the PIO. You can disable the printer, or select another company name. By changing this value to 0x3B, you get "Schneider" instead of "Amstrad" (0x3F) on the opening screen. Meaning of the bits: b7 = 0 (TTL-signals from tape; not used) b6 = 0 (0 = printer ready, 1 = busy) b5 = 1 (EXP-signal) b4 = 1 (1 = vsync with 50 Hz or 0 = with 60 Hz; not used) b3,b2,b1 = 111 select company : Isp (000), Triumph(001), Saisho(010), Solavox(011), Awa(100), Schneider(101), Orion(110), Amstrad(111) b0 = 1 (vsync : toggles between 0 and 1 in the emulator, the duration depends on VSYNC_CT.) ROM_BLOCKS = {T} (0) {T} {T} {T} (repeat this line - times !) Describes, which ROMs should be loaded : - is the number of ROMs to load. Every ROM has a size of 0x4000 bytes. ( ranges from 0 to ca. 8, depending on the free memory left.) - is the number assigned to the ROM, that means, it is selected by 'OUT &DF00,' . Possible values are : 0 : Foreground-ROM (p.ex. BASIC) 1 - 251 : Background-ROMs. On a CPC 664/6128, the ROMs 1-15 are automatically initialized during reset (on a CPC 464 only 1-7). 255 : Lower-ROM (p.ex. OS; has only in emulator this number). - is a file in the directory ROM_PATH, which contains the ROM. - is a number of bytes preceiding the ROM-image in file . An AMSDOS - header is overread automatically, so don't take any regard to it. With an offset it is possible to load several ROMs from the same file. If you inspect the lines 255 Z80CPC.ROM 0x0000 0 Z80CPC.ROM 0x4000 you maybe notice, that the lower-ROM and the foreground-ROM are loaded one after another from the same file. 6.5 Compatibility of the emulator (or: what is supported) : ------------------------------------------------------------ 6.5.1 The Z80 - CPU : ---------------------- All Z80-instructions, also so-called illegal ones. You have the choice between a slow Z80-emulation written in C and a fast Z80-emulation written in assember by Juergen Weber. With the "CO-CPU" - technique, every Z80-instruction is emulated simultaneously by the slow and the fast version, so it gets very slow, but by comparing the registers after each instruction many errors are found. Certainly this was only used during program-developement. 6.5.2 The Gate - Array : ------------------------- - all 32 colours of the CPC (27 different ones) - all three screen-modes (x, y, colours) : mode 0 = 160x200x16 mode 1 = 320x200x4 mode 2 = 640x200x2 - ROM-banking (16KB OS, 16KB BASIC, 16KB AMSDOS and additional ROMs) 6.5.3 The PAL (Programmable Logic Array) : ------------------------------------------- - RAM-banking (8*16KB = 128KB) Banking can get very slow, since memory blocks must be swapped. Perhaps EMS-memory would help ... 6.5.4 The CRTC 6845 (Cathode Ray Tube Controller) : ---------------------------------------------------- - screen-base and -offset for hardware-scrolling - several screen-sizes from 0x0 to 80x25 with CRTC-registers 1 and 6. 6.5.5 The PIO 8255 (Programmable Input-Output) : ------------------------------------------------- - Keyboard (connected to PSG) - vsync-emulation 6.5.6 The PSG (Programmable Sound Generator) : ----------------------------------------------- (no sound yet) 6.5.7 The FDC (Floppy Disc Controller) : ----------------------------------------- - all necessary FDC-commands to control two drives A and B (including sector read/write, seek track, read sector-ID, ... ; format track is suppressed.) - very flexible disc-formats (up to 18 sectors per track). Create them with CPCREAD. 6.5.8 The Tape : ----------------- - very fast by ROM-bypass. Access files in TAPE_PATH (see configuration-file) 6.5.9 The Centronics : ----------------------- - Printer output to the file PRINTER in TAPE_PATH (see configuration-file). You can also use the 8-bit printer-patch ! 6.6 Incompatibilities (or: what's not supported) : --------------------------------------------------- - overscan (at most for some silly demos) (will never be implemented - too slow) - several screen-modes on the same screen (flickering) - sound (not a single tune) - PC-joystick (only the fire-buttons) - OS/2 dos-box : flickering during set_palette (no hsync aviable) - program Copymate : load/save impossible, since it uses a trick to detect the number of sectors per track - please report all bugs you find ! A1. APPENDIX : =============== A1.1 Command line parameters : ------------------------------- You can start CPCEMU.EXE on several ways by using options, introduced by '-' or '/', p.ex 'CPCEMU.EXE /s' . The following options are aviable: CPCEMU /f : starts CPCEMU in fast-mode (default) CPCEMU /s : starts CPCEMU in slow-mode CPCEMU /d : starts CPCEMU in debug-mode (Consult appendix "The Debug-Menu" (A1.2).) CPCEMU /h : displays a help-screen The option '/d' is automatically used, if an unknown option was specified. A1.2 The Debug - menu : ------------------------ The complete register-set of the CPU is displayed and can be modified. You can "dump" the momory, disassemble or modify it. You can load or save areas im memory. And the most interesting thing: You can single-step through programs ! (Similar to a real debugger.) A1.2.1 Overview of the debug-menu : ------------------------------------ R)un T)race S)tep A)ssem D)ump I)nput L)oad saV)e M)ode F)ast Q)uit AF=0000 BC=0000 DE=0000 HL=0000 IX=0000 IY=0000 SP=0000 PC=0000 IR=0000 AF'=0000 BC'=0000 DE'=0000 HL'=0000 IFF1=0 IFF2=0 IMD=0 NZ NC PO P 0000 : 01 89 7F LD BC,&7F89 -f-> The first line displays the aviable commands, use the capitalized letters. The next two lines show the actual values of the Z80-register. The next one disassembles the actual instruction at PC position and the last is a prompt waiting for your input. ('f' indicates that you are using the fast-CPU.) A1.2.2 Preliminaries : ----------------------- Parameters in special brackets are optional [opt]. Use only hexadecimal values, p.ex = 0000-ffff "" signals you, that you are in a special mode. You may press to continue. leaves this mode (use p.ex. b). Commands are letters, mostly followed by an optional address. Between the letter and this address must be a blank or tab. Without an address, PC (program-counter) is assumed as default. A1.2.3 Overview of the commands : ---------------------------------- R)un : r [] : starts emulation from PC or an optional address. Examples: -f-> r starts emulation from PC -f-> r 100 sets PC to 0x100 and starts emulation T)race (trace into) : t [] : executes only the actual displayed instruction. Use to continue in this mode, and so on. goes back to normal mode. All single-step-commands are executed by the slow-CPU (even if "-f->" is displayed), since there is no counter in the fast-CPU any more. S)tep (step over) : s [] : executes the next instruction. Rather all instructions, until PC is equal to the following instruction. This can take a long time p.ex after a 'Ret'. In this case F10 helps (as usual). All single-step-commands are executed by the slow-CPU (even if "-f->" is displayed), since there is no counter in the fast-CPU any more. A)ssemble (rather disassemble) : a [] : disassemblies the next 16 instructions. Use to continue in this mode, and so on. goes back to normal mode. D)ump : d [] : shows an hex-ascii-dump of the following 256 256 bytes from address (or PC). Use to continue in this mode, and so on. goes back to normal mode. I)nput (modifying memory) : i [] : shows the actual memory-address with its current value, which you can take by or change by . Leave this mode by using an invalid number like '-1' : -1 . L)oad (loading a program) : l [] : prompts you for a filename and loads it from the directory TAPE_PATH to An AMSDOS-header is recognized. Look at Appendix "Structure of the AMSDOS-header". Examples: -f-> l demo : loads file 'demo' to the actual PC -f-> l a000 myprog : loads file 'myprog' to address 0xA000 saV)e (saving a program) : v [] : prompts you for a filename and the length of the memory-block. This block is saved from (or PC), as binary-file in the directory TAPE_PATH, which means with an AMSDOS-header. Look at Appendix "Structure of the AMSDOS-header". Example: -f-> v demo 4000 : saves file "demo" from PC with length 0x4000. M)ode (changing the display-mode) : m : Changes dislay-mode : register-display, instruction- disassembling on/off. F)ast (selecting the type of emulation) : f : Flips between the fast Z80-emulation (developed in assembler by Juergen Weber, default) and the slow one (written in C). The prompt toggles between "-f->" for fast and "-s->" for slow. All r, s, t-commands refer to the selected type of emulation. Q)uit (leaving the program) : q : quits the emulator. A1.2.4 Manipulation of registers : ----------------------------------- In addition to the one-letter-commands you can change register- values with the syntax: '=' Examples: - af=345 : set register AF to 0x0345 - pc=a000 : set program-counter to 0xA000 Here, '=' is handled as delimiter, so no additional blanks are necessary (and you can also write ''). You can modify all displayed registers, thus AF, BC, DE, HL, IX, IY, SP, PC, IR, AF', BC', DE', HL', and also IFF1, IFF2 and IMD. A1.3 Function of the ROM - Bypass : ------------------------------------ Some special instructions are implemented in the Z80-emulation. They call special functions only supplied by the emulator. They are entered directly in ROM, so it is still possible to patch the RAM-vectors. The following instructions are aviable : ED FC xx USER &BCxx (only valid for some RAM-vectors) Similar to a call-instruction to an internal function. The following values for xx are legal : 65 : CAS INIT (BC65) 77 : CAS IN OPEN (BC77) 7A : CAS IN CLOSE 7D : CAS IN ABANDON 80 : CAS IN CHAR 83 : CAS IN DIRECT 86 : CAS RETURN 89 : CAS TEST EOF 8C : CAS OUT OPEN 8F : CAS OUT CLOSE 92 : CAS OUT ABANDON 95 : CAS OUT CHAR 98 : CAS OUT DIRECT 9B : CAS CATALOG In addition to that, you can use the user-break-instruction ED FC FC USER &BCFC , it stops the emulation at once. A1.4 Structure of Disc - Images : ---------------------------------- Disc-image files consist of a 0x100-byte disc-info block and for each track a 0x100-byte track-info block, followed by the data for every sector in that track. A1.4.1 The Disc - Information block : -------------------------------------- Byte (hex) : Meaning: 00 - 21 MV - CPCEMU Disk-File\r\nDisk-Info\r\n (as characteristic) 22 - 2F unused (0) 30 number of tracks (40, 42, maybe 80) 31 number of heads (1, 2 not yet supported) 32 - 33 size of one track (including 0x100-byte track-info) With 9 sectors * 0x200 bytes + 0x100 byte track- info = 0x1300. 34 - FF unused (0) A1.4.2 The Track - Information block (for every track) : --------------------------------------------------------- Byte (hex) : Meaning: 00 - 0C Track-Info\r\n 0D - 0F unused (0) 10 track - number (0 to num.of tracks -1) 11 head - number (0) (maybe 1 later) 12 - 13 unused (0) Format-track-parameters: 14 BPS (bytes per sector) (2 for 0x200 bytes) 15 SPT (sectors per track) (9, at the most 18) 16 GAP#3-format (gap for formatting; 0x4E) 17 Filling-byte (filling-byte for formatting; 0xE5) Sector-info (for every sector at a time): 18+i track-number \ 19+i head-number | sector-ID-information 1A+i Sector-number | 1B+i BPS / 1C+i state 1 error-code (0) 1D+i State 2 error-code (0) 1E+i , 1F+i unused (0) Annotations: The sector-data must follow the track-information-block in the order of the sector-IDs. No track or sector may be omitted. Use CPCREAD to copy CPC-discs into this format. A1.5 Structure of the AMSDOS - Header : ---------------------------------------- Byte (hex:) Meaning: 00 user-number (0 , possible values 0-15) 01 - 0F filename+extension (possibly filled with 0) 10 block-number (0) 11 last-block-flag (0) 12 file-type (0=basic, 1=protected basic, 2=binary,...) 13 - 14 length of block (0) 15 - 16 load-address (0-FFFF) 17 first-block-flag (0) 18 - 19 logical length (0-FFFF) 1A - 1B entry-address (0-FFFF) 1C - 3F free for the user (0) 40 - 42 real length of file (1-FFFFFF) 43 - 44 checksum of bytes 00-42 45 - 7F unused (random values from sector-buffer) Annotation: A header stands at the beginning of every non-ASCII file. It is identified by calculating the checksum. Bytes 00-3F originate from the "cassette-area", where files were divided up into blocks. Necessary are the bytes 12, 15-16, 1A-1B, 40-42, 43-44 . A1.6 Information on the CPC : ------------------------------ It is possible to write several books about this topic, maybe in a later doc. A1.7 Letter from AMSTRAD : --------------------------- I have written the following letter to AMSTRAD: Dear Sirs, I would like to offer you the most outstanding program ever written ! It is a CPC-emulator on PC. You might say, "CPC, that home-computer we designed years ago, that is over !" But there are many people still using it, potential customers of Amstrad-PC's. An emulator would be another reason to buy a PC, they can continue using the old well known programs during a transitional period. For people who already have a PC it is fascinating, too. I was totally surprised to see the CPC-opening screen on a complete different computer the first time. It drives me to improve the emulation (in former times it was only black and white ...), so today I would call it a "software CPC". Certainly, it can be improved. Some more details of the emulator are enclosed. Unfortunately I cannot continue programming the emulator without support (I am only a student). All programs I have ever written are Public Domain, also the current version of CPCEMU. If you are interested, I can send you the emulator for testing. If not (but I do not think so), I need to know, under which legal condition I can include the original Amstrad-CPC-Rom to make a shareware package. (Some people asked me for that.) . I have received the following answer : . Dear Mr Vieth Thank you for your recent letter concerning the CPC. Please be advised that the CPC ROM is protected by copyrights and therefore regretfully we are unable to offer any assistance in this matter. We are sorry we have been unable to assist you on this occasion and regret the inconvenience caused. . So I'm not allowed to enclose the ROMs. But who has the copyright ? A1.8 History of program developement : --------------------------------------- A1.8.1 Z80EMU (only a Z80 with less CPC) : ------------------------------------------- - v1.0 (1991) first version in pascal (only Z80-emulation) - v1.2 (12.8.1992 - 16.8.1992) first version in C (translated with TPTC) Z80-problems: P-flag set with ADD HL..., DAA, ldir; Z-flag set with BIT... Z,S-flags set with Rotate; ROMs possible - v1.3 (18.8.1992) port-adressing wrong in lo-byte. New memory-management (128 KB RAM, 32 KB ROM) - v2.0 (18.8.1992 - 22.8.1992) Co-CPU-technique implemented to find errors (mit separated memory for the CO-CPU). Z80-problems: H-flag set after AND... ; CPI... sets N-Flag; Screen colours blue and yellow (former black and white) - v2.1 (25.8.1992 - 27.8.1992) All pens, colours from the CPC in all modes; only the viewing screen is written to. Co-Z80-error: alle (ix+zz) with negative distance were wrong ! Forgotten to take 'signed char'. - v2.2 (30.8.1992 - 3.9.1992) New keyboard-routine, set palette without flickering (hsync). "Need-Rom" with Copymate introduced. - v2.3 (15.9.1992 - 19.9.1992) FDC-emulation for sector load/save. Co-Z80-error: LD XH... was LD H... - v2.3b (19.9.1992) Screen-update only on blocks 0..3 (not 4..7); Port FCxx same as FBxx (for CP/M Plus). At that time, I didn't know that OUTI... pre-decrements the B-register. - v2.4 test (25.10.1992) Only R-register-emulation, if desired (per define); Now screen-update every n.interrupt and not for every single byte written in memory. (Still very slow, it's written in C). New memory-management with blocks aligned to segments. - v2.5 test (31.10.1992) Changed memory-management. Hardware-scrolling and different screen-sizes possible. - v2.6 test (5.11.1992) New keyboard-handler by Arnt Gulbrandsen: all key-combinations possible. Screen-update in assembler. - v2.7 test Unsuccessfully tried to include the fast-Z80-emulation by Juergen Weber. - v2.8 Improved Screen-update: Only changed parts are modified on the screen. - v2.9 Timer-handler with 300 interrupts. Fast-emulation runs only, if no ROM (banking) is needed. A1.8.2 CPCEMU (now a CPC) : ---------------------------------- - v0.2 (23.12.1992), following Z80EMU v2.9 After nearly 4 hours with the Turbo-Debugger I've found the error hanging the fast-emulation: pushed ES instead of DS. - v0.3 (28.12.1992 - 29.12.1992) Set N-flag for INI,OUTI. CPI in fast-Z80 set wrong flags. RL(HL) used read-segment(DS) instead of write-segment(ES). LD A,R now produces random-numbers; All Tape-routines implemented (but wrong CAS IN CHAR). - v0.4 (1.1.1993) IN A,(n): A to b8..b15 (instead of B); RAM-configuration 0xc3: corrected to 0,3,2,7 (for CP/M Plus). KC-Compact (a CPC-compatible from former DDR) uses port EE00 - EE3D, but for what ? - v0.5 (28.1.1993 - 8.2.1993) INIR,... R-register-incrementation depends on B, not on BC. CAS IN CHAR corrcted (wrong patch for CPC 6128). - v0.6 (23.3.1993 - 24.5.1993) Somemone mentioned that the OUTI-instructions pre-decrement the B-register ! Now C-parts also in 386-code (with Borland C++ v3.1) Disk-image-files now suffix .DSK. CPCREAD.PAS corrected (head not initialized with 0) and translated to CPCREAD.C . Pio-8255-port-addressing improved (can read, even if port is programmed for output, ...) - v0.7 (26.7.1993 - 29.8.1993) (inoffiziell) Tatally new source, modularized, ... Configuration-file, more ROMs possible. Changed company-name from 'Schneider' to 'Amstrad'. (The user can choose now.) RAM-banking-error removed. New documentation in german. - v0.8 (30.8.1993 - ) Slow-emulation: parity-instructions improved by using a table not only for parity. Z80: ED xx with illegal xx is ignored. New documentation in english. A1.9 Acknowledgments : ----------------------- - Special thanks to Juergen Weber, not only for many hints and suggestions, especially for the fast Z80-Emulation from his CP/M-emulator ZSIM. Juergen G. Weber Wiesentalstrasse 1 74523 Schwaebisch Hall Federal Republic of Germany email: weberj@dia.informatik.uni-stuttgart.de - Thanks to Arnt Gulbrandsen for his JPP source, where I found ideas to the keyboard-handler, and the joystick-routine. By the way, JPP is a very good emulator for the Spectrum. - Thanks to Gilles Molinari for his transfer program. - Thanks to AMSTRAD fow answering my letter. (It was my first business(?) letter). - And thanks to the many users for sending me suggestions or having ideas ... - (Please excuse my english. This is the first doc.) A1.10 Trademarks : ----------------------------- CP/M, CP/M 2.2 and DRDOS are trademarks of Digital Research. MS-DOS is a trademark of Microsoft. IBM PC, PC-XT, PC-AT and OS/2 are trademarks of International Business Machines. CPC, AMSDOS by Amstrad, BORLAND C, TASM (Turbo Assembler) by Borland, 22DISK by SYDEX ... A1.11 Address of AMSTRAD : --------------------------- Amstrad plc, Brentwood House, 169 Kings Road, Brentwood, Essex CM14 4EF A1.12 The author : ------------------- Marco Vieth (22), Student at the University of Paderborn (7.class ?) (WS 93/94) Have fun ! ----------------------
