My article about CD-ROM programming has been published.

Hello All! Subject At http://www.zx-news.narod.ru/zxn/cdromzx.htm Comments/suggestions for soap. Vega/ex-Style Group. FIDO: 2:5030/885.34 ZXNET: 500:812/5.13 E-mail: vega56@mail.ru

Press RESET immediately, Nikolaj! 22 May 02 21:06, Nikolaj Amosov wrote to Vlad Sotnikov: VS>> Subject. At http://www.zx-news.narod.ru/zxn/cdromzx.htm VS>> Comments/suggestions in advance. NA> Like instead of ZX-NEWS or something? Can I do it in text soap, but in general NA> you can go here too, because it’s in the topic. (C) Vlad Sotnikov/Vega, 2002 (vega56@mail.ru) (R) The ZX-News Site (www.zx-news.narod.ru) FEATURES OF PROGRAMMING CD-ROM ON THE SPECTRUM Contents 1. Introduction 2. A little about CD-ROM 3. CD formats 3.1. "Red Book" 3.2. "Yellow Book" 3.3. ISO-9660 4. Routines for SMUC 4.1. Routines for NEMO HDD controller 5. ATA commands 6. Determining the presence of a CD-ROM 7. CD-ROM identification table 8. Transfer of ATAPI packet 9. Description of commands General commands 9.1. "Dummy" 9.2. Positioning 9.3. Tray management Information commands 9.4. Reading manufacturer parameters 9.5. Getting general parameters 9.6. Setting General Settings 9.7. Operation error code 9.8. Determining disk size 9.9. Audio Information9.10. Sector information 9.11. Track information Audio disk management commands 9.12. Playing audio in blocks 9.13. Playing audio in MSF 9.14. Stop/resume playback 9.15. Stop playing Read Data Commands 9.16. Reading data in MFS 9.17. Reading data in sectors 10. Example of reading data on Spectrum 11. Disk file system structure 11.1. TOC (Disc Table of Contents) 11.2. Catalog. Description of files 12. Conclusion 1. INTRODUCTION ═В═ newspaper ZX-News #54 I published an article about features of hard drive programming on the Spectrum. Numerous letters that came to me after the publication of the article, showed that interest in low-level programming There is quite a lot of equipment among spektrumists. What, in fact, prompted me to write a continuation of the article, where I want to tell you about another IDE device that received Now universally accepted - CD-ROM. Its appearance on the Spectrum is not accidental - the prerequisite was creation of IDE controllers. This is SMUC on Scorpion, and HDD controller by Nemo. And although the main purpose of creating these devices was the connection of the hard drive, however, a side effect the result was the ability to work with CD-ROM. Metogether with Pavel Vasiliev (POL) a program has already been written, allows you to read data from CDs. Program supports both controllers (SMUC and NEMO). So that's it, what is written here serves the sole purpose of making it easier for people writing similar programs, but in no way can claim for a documentary description of the device. So they can encounter errors and inaccuracies. However, The information provided here should make it a lot easier people who decide to support CD-ROM in their programs, this work. Unlike my previous article, designed for for beginners, here I decided not to explain too much times of elementary things and concepts to limit the text to volume. I assume that the reader has already read my article in ZX-News #54 and has basic programming skills in assembler and hard drive programming. Purpose registers and many of the routines I use here, you You can find it in my article on HDD programming. 2. A LITTLE ABOUT CD-ROM In its features, CD-ROM is very different from Winchester. Firstly, CD-ROM can be classified as Read-only devices. Despite the fact that the practice of recording on The compact disc has now spread quite widely, however doing less is quite difficult, and is unlikely to be possibleon Spectrum. However, despite this, CD-ROM is is now one of the most popular external storage media in mainly due to the cheapness of CDs and the convenience using it as an archive. CD-ROM is an external storage medium. It consists of A CD player into which CDs are inserted. Volume disks range from 640 to 700 megabytes. You can also highlight another important part of the CD-ROM - the tray. This platform on which CDs are placed. She is moving part of the device, and is also programmable management. Like a hard drive, a CD-ROM can be either a Master or a Slave device. However, the principle of issuing commands is somewhat different from the one used with the hard drive, and was described by me in a previous article. For programming the hard drive used a set of registers (or ports), each of whom performed a specific role (command register, status register, data register), and commands were given through the command register, and the set of these teams were limited. The situation is completely different with CD-ROM. The command is given via a data packet, usually consisting of 12 byte. This standard is called ATAPI (ATA Packet Interface - Packet ATA protocol). To Command Register the command “write data” is given, and then through the RegistersA packet of 12 bytes is transferred to the CD-ROM. The reason for these difficulties are that the ATA set of instructions and registers is not suitable for some CD-ROM command structures. Therefore ATAPI devices support only a minimum set traditional ATA commands. 3. CD FORMATS 3.1. "Red Book" Compact discs were originally created by Philips and Sony. to reproduce audio information. Now this is - regular audio discs that can be played on any CD player. Data format defined as "Red book" and looks like this: on the disk there is a certain number of audio tracks (tracks). The track is usually one song. The track, in turn, is divided into sectors that are 1/75 of a second in length and contain 2352 bytes of data in audio form. 3.2. "Yellow Book" Later, the same manufacturing companies introduced another disk standard known as the "Yellow Book". It contained provided the ability to save information on disk, not being audio. The sector format has been revised: now 2352 bytes of the audio sector were perceived as follows way: 12 bytes of synchronization. 4 bytes of head information. 2048 bytes of user data. 288 bytes of error correction. This is the basic standard. There are also "Green" standardsbook", "Orange book", but they are all variations these two main standards. In addition, there is ISO-9660 standard, which was originally intended for data storage and has its own file structure. B It does not provide storage of audio information. At the same time you need to keep in mind that modern CD-ROMs independently determine the standard in which the disc is recorded and operate either with audio or data. In the second case we need read 2048 bytes of data. This is the length of the sector CD and the minimum length of read data. 3.3. ISO-9660 The ISO-9660 standard defines the file storage structure on disk. It will be described in detail by me in Chapter 11 - "Disk file system structure." To PC for conversion This structure in MS-DOS format is the file MSCDEX.EXE. On in fact, it's a pretty easy to understand file structure. The disk is divided into sectors of 2048 bytes. At 16 sector contains information about the disk and location root directory. All directories follow CD, and then come the files. Moreover, the information in files are located sequentially, sector by sector. This structure is very similar to TR-DOS. 4. SUBROUTINES FOR SMUC Despite the fact that, as I wrote above, I will refer to examples in my previous article, however, I decidedgive here the main routines used in programming an IDE device (hard drive, CD-ROM) via SMUC controller. This is done so that without text everything the examples given here were assembled without errors and were a fully functional driver for working from CD-ROM. Firstly, I will once again list SMUC's ports, which correspond to the registers of the IDE device. I remind you once again, that they are called from under TR-DOS. Read from port || Write to port #FFBE Command Register || Status Register #FEBE Drive/Head Register #FDBE Cylinder register (high part) #FCBE Cylinder register (low part) #FBBE Sector number register #FABE Sector counter register #F9BE Error register || Additional register opportunities #F8BE Data register (low part) #D8BE Data register (high part) ;Write a value to the port. ;IN: [BC] - port number ; [A] - value OUT_A LD IX,#3FF0 PUSH IX JP #3D2F ;Read value from port. ;IN: [BC] - port number ;OUT: [A] - value IN_A LD IX,#3FF3 PUSH IX JP #3D2F ;Waiting for the device to become free. NO_BSY LD BC,#FFBE CALL IN_A RLCA: RET NC JR NO_BSY ;Waiting for data transfer to be ready. WAIT_DRQ LD BC,#FFBECALL IN_A BIT 3,A RET NZ JR WAIT_DRQ ;Let's see if an error has occurred. NO_ERROR LD BC,#FFBE CALL IN_A RLCA RET ;Selecting a Slave device. SEL_SLAVE LD A,#B0 LD BC,#FEBE CALL OUT_A LD BC,#FEBE CALL IN_A RLCA: RET ;Write a number to the Cylinder Register. HL_TO_LEN LD BC,#FCBE LD A,L CALL OUT_A LD BC,#FDBE LD A,H CALL OUT_A RET ;Reading a number from the Cylinder Register. LEN_TO_HL LD BC,#FCBE CALL IN_A LD L,A LD BC,#FDBE CALL IN_A LD H,A RET 4.1 Routines for the NEMO HDD controller For those who use the NEMO hard drive controller (for computer KAY), I will also give individual subroutines. This controller is convenient because it does not require separate Professional ROM, as for the SMUC controller on Scorpion. This controller just needs to be inserted into the system connector any Spectrum-compatible computer. In addition, for accessing it does not need to call the TR-DOS ROM every time - the ports here are open, which, in turn, increases speed of work with CD-ROM. And the last thing is the controller circuit so simple that it can be assembled on your own. Read from port || Write to port#F0 Command register || Status Register #D0 Drive/Head Register #B0 Cylinder register (high part) #90 Cylinder register (low part) #70 Sector number register #50 Sector counter register #30 Error Register || Additional register opportunities #10 Data register (low part) #11 Data register (high part) ;Write a value to the port. ;IN: [BC] - port number ; [A] - value OUT_A OUT (C),A RET ;Read value from port. ;IN: [BC] - port number ;OUT: [A] - value IN_A IN (C),A RET ;Waiting for the device to become free. NO_BSY LD BC,#F0 CALL IN_A RLCA: RET NC JR NO_BSY ;Waiting for data transfer to be ready. WAIT_DRQ LD BC,#F0 CALL IN_A BIT 3,A RET NZ JR WAIT_DRQ ;Let's see if an error has occurred. NO_ERROR LD BC,#F0 CALL IN_A RLCA RET ;Selecting a Slave device. SEL_SLAVE LD A,#B0 LD BC,#D0 CALL OUT_A LD BC,#D0 CALL IN_A RLCA: RET ;Write a number to the Cylinder Register. HL_TO_LEN LD BC,#90 LD A,L CALL OUT_A LD BC,#B0 LD A,H CALL OUT_A RET ;Reading a number from the Cylinder Register. LEN_TO_HL LD BC,#90 CALL IN_ALD L,A LD BC,#B0 CALL IN_A LD H,A RET Further in the text (for subroutines for determining the availability CD-ROM and data reading) to users of the NEMO HDD controller you need to replace the registers (ports) of the SMUC controller corresponding ports of the NEMO controller. 5. ATA COMMANDS These are auxiliary commands that are transferred to the CD-ROM through the Command Register, not through the package. There are only such teams 4: 1. #A0 - ATAPI packet transmission command. More details usage will be discussed below. 2. #08 - Soft reset. Full initialization in progress CD-ROM. 3. #A1 - CD-ROM identification. Similar to the #EC command for Winchester. 4. #EC - Treated as an error, but in the Cylinder Register the value #14EB is set - the ATAPI device sign. 6. DETERMINING THE PRESENCE OF A CD-ROM To determine the presence of a CD-ROM, you must run the following steps: 1. Select the Slave/Master device. 2. See the absence of the BSY signal. If it's busy, it means no device. (Please note that before this CD-ROM did not execute any of your commands, otherwise the BSY flag may also be installed). 3. Issue a master reset command. Although you can do without this. 4. Write a number different from #14EB into the Cylinder Register. For simplicity, you can simply write 0.5. Enter the ATA command #EC into the Command Register and wait a couple interrupts. 6. Read the Cylinder Register. It must contain a number #14EB. If so, then the CD-ROM is connected. Otherwise In this case it could be a simple hard drive. In this case it is necessary Please note that the CD-ROM will report an error in the Error Register. This is fine. Here I will give a subroutine that determines the presence CD-ROM. ;IN: A=#00 - Master. ; A=#B0 - Slave CD_INI LD BC,#FEBE CALL OUT_A LD BC,#FFBE CALL IN_A RLCA JP C,NO_CDROM LD HL,0 CALL HL_TO_LEN LD BC,#FFBE LD A,#EC CALL OUT_A CALL NO_BSY CALL LEN_TO_HL LD BC,#EB14 OR A SBC HL,BC JP NZ,NO_CDROM RET NO_CDROM... Now we have made sure that we have an ATAPI device connected. However, to be completely sure, it would be a good idea to check Is this really a CD-ROM? To do this you need to look at the 1st byte in CD-ROM identification table (transmitted by command #A1). 7. CD-ROM IDENTIFICATION TABLE The identification table is one sector of data, in which contains information about a specific CD-ROM. Sector called by ATA command #A1. After sending the command to us you need to accept 2048 bytes from the CD-ROM. Attention! Data inthis table, as well as in a similar table on the hard drive, upside down! The high byte comes first, then the low byte. to you It is necessary to swap every two adjacent bytes. Below is an example of such a subroutine: ;IN: [HL] - address for receiving data. ; [BC] - number of bytes. TRANS_IN PUSH BC CALL NO_BSY CALL WAIT_DRQ POP B.C. OR A RR B RR C JR NC,$+3 INC B.C. TRANS_IN1 PUSH BC LD BC,#F8BE CALL IN_A LD(HL),A INC HL LD BC,#D8BE CALL IN_A LD(HL),A INC HL POP B.C. DEC B.C. LD A,B OR C JR NZ,TRANS_IN1 RET So, to read the identification table, we need execute the following subroutine: CD_INITAB LD A,#A1 LD BC,#FFBE CALL OUT_A LD HL,MY_BUFF LD BC,#0200 CALL TRANS_IN RET And we have an identification table in our memory. In it contains the following information: 00, bit 0 - Packet length: 0 - 12 bytes, 1 - 16 bytes. 01, bit 0-4 - Device type: 5 - CD-ROM 20-39 - Serial number. 40-45 - Something from the manufacturer 46-53 - Firmware version 54-93 - Model name 94-95 - Something from the manufacturer The remaining parameters are not so important for us. Soway to make sure that we are really connected CD-ROM, and not another ATAPI device, we need to read in accumulator byte from table at offset 1, execute command AND #1F and see if it is equal to 5. Although the probability of connecting an ATAPI device to the Spectrum is not being a hard drive, it’s unlikely, but nevertheless I advise carry out this check. 8. TRANSFER OF ATAPI PACKET This is nothing more than direct programming CD-ROM. The commands that he perceives are transmitted to him in packet consisting of 12 bytes. The first byte of the packet is command code, and the remaining 11 bytes are command parameters. To begin with, I will give a subroutine that passes 12-byte package on CD-ROM. It does the following: writes command #A0 to the ATA Command Register (ATAPI transfer packet) and transmits 12 bytes through data registers, and being an ATAPI package. Attention! When transmitting a packet, you must always specify the device we are working with (Master/Slave). ;Transfer ATAPI packet. ;IN: [HL] - packet address. SEND_ATAPI PUSH HL CALL SEL_SLAVE LD HL,#0800 CALL HL_TO_LEN LD BC,#FFBE LD A,#A0 CALL OUT_A POP HL LD BC,12 ;data transfer. ;IN: [HL] - data address. ; [BC] - number of bytes. TRANSFER_OUT PUSH BC CALL NO_BSYCALL WAIT_DRQ POP B.C. OR A RR B RR C JR NC,$+3 INC B.C. TRANS_OUT1 PUSH BC INC HL LD A,(HL) LD BC,#D8BE CALL OUT_A DEC HL LD A,(HL) LD BC,#F8BE CALL OUT_A INC HL INC HL POP B.C. DEC B.C. LD A,B OR C JR NZ,TRANS_OUT1 RET And a few words about what this command should look like package. In my description I will present it in this way form: #00 - "Dummy". DB 0 DS 11 The first byte is the command code. The rest are parameters. I describe unused bytes with the DS assembler command (sequence of zeros). Although unused data is not are analyzed, for compatibility it is better to set them to 0. So, the package itself can be designed like this: AP_00 DB 0 DS 11 And it will be called like this: LD HL,AP_00 CALL SEND_ATAPI ... 9. DESCRIPTION OF CD-ROM COMMANDS General commands 9.1. "Dummy" This command was given as an example by me in previous chapter. The packet consists of 12 zeros. This team is notperforms no action. However, it is extremely necessary - the fact is that for unknown reasons the CD-ROM refuses execute many commands and reports an error. In particular, this happens immediately after changing the media (Master -> Slave or vice versa). Therefore I strongly recommend you Before each command, call a "dummy". That's exactly how I am got my CD-Copier program working on Spectrum. In other words, executing the command described package AP_?? should look like this: LD HL,AP_00 : CALL SEND_ATAPI LD HL,AP_?? : CALL SEND_ATAPI ... 9.2. Positioning ;#01 - Positioning on track 0. DB #01 DS 11 This command sets the media heads to track 0. B I have never used this command in my program. ;#2B - Positioning in MSF format. DB #2B DS 2 DB minutes DB seconds DB fractions of a second DS 6 MSF (Minute/Second/Frame) is one way positioning on the disk. It is defined in minutes/seconds/fractions of a second that would have passed when reading from the beginning of the disk at speed 1. The format is convenient when working with audio discs. 9.3. Tray management ;#1B - Tray management. DB #1B DS 3 DB Function DS 7 Function: 0 - Enter Sleep mode. 1 - Stop playing/reading.2 - Pull out the tray. 3 - Push in the tray. As you can see, the functions of this command are not limited to one tray management. Sleep mode is a reduced mode power consumption, the drive stops or slows down rotation until the command to read data arrives. Function code 1 convenient to use to stop playing a melody. Tray management is carried out only if it not blocked. ;#1E - Tray lock. DB#1E DS 3 DB Function DS 7 Function: 0 - unlock tray. 1 - block tray. The command blocks the action of command #1B. Information commands 9.4. Reading manufacturer parameters It contains almost the same data as in identification table called by ATA command #A0. ;#12 - Read the manufacturer parameters string. DB #12 DS 3 DB string length. DS 7 The string length is usually 36. The following data is returned: +0 - device type (CD = 5) +1 - bit 7: removable media supported +2 - ISO, ECMA and ANSI versions. +3 - 0, for SCSI-2 compatibility +4 - length of the remaining block +5 - reserve +7 - 0, for SCSI-2 compatibility +8 - manufacturer's string (there is 'ATAPI') +16 - product name +32 - revision 9.5. Getting general parametersI have not studied this command, so I quote it from the description without changes or comments. You have to either study it action yourself, or skip it, because she reports specific information about the CD-ROM and for the Spectrum decisive doesn't matter. ;#5A - Get general parameters. DB #5A DB 0 DB Page - defines the required parameters, consists of two bit fields: bits 1?5 - number of the required parameters page: %00000001 - error correction parameters %00001011 - general parameters %00001110 - audio control %00101010 - device parameters (read only) %00111111 - all pages bits 6?7 - bits of the required page type: %00000000 - current values %01000000 - changed values %10000000 - default values %11000000 - saved values DS 4 DW Length; table length DS 3 The command is informational, issues the corresponding parameters page. General title: 00-01 - Length of the entire block (without the first word) 02 - Drive status 03-07 - ? Title of each page: 08 - Page number from the request 09 - Page length Page #01 - bug fixes 10 - Error correction option 11 - Read repeat counter Page #0D - general parameters 10 - ? 11 - Inactivity timer multiplier12-13 - Number of S units in M unit for MSF format (60) 14-15 - Number of F units in S unit for MSF format (75) Page #0E - audio parameters 10 - Parameter not used, but can be changed 11-12 - ? 13 - =0 LBA is always equal to the sector number, high bit indicates the following field is correct 14-15 - Number of logical blocks per second for playback. (usually not used) 16 - ml. tetrad - bits of channel 0 output port 17 - channel volume 0 18 - ml. tetrad - bits of channel 1 output port 19 - volume of channel 1 20 - ml. tetrad - bits of channel 2 output port 21 - channel 2 volume 22 - ml. tetrad - bits of channel 3 output port 23 - channel 3 volume Page #2A - device parameters (read only) ; function presence/absence bits 12 - bit 0 - audio playback bit 1 - composite audio/video stream bit 2 - Digital out to port 1 bit 3 - Digital out to port 2 bit 4 - read sectors Mode 2 Form 1 bit 5 - -----//-------- Mode 2 Form 2 bit 6 - Reading multi-session disks bit 7 - ? 13 - bit 0 - Reading the "Red Book" via the Read-CD command bit 1 - Reading the "Red Book""with accurate stream" bit 2 - Read subchannel bit 3 - Support for subchannel data deinterleaving bit 4 - Support "C2 error pointers"bit 5 - ISRC read support bit 6 - UPC reading support bit 7 - ? 14 - bit 0 - media lock bit 1 - read lock status bit 2 - Disk prevent jumper present bit 3 - media eject command bit 4 - ? bit 5?7 - Bootloader type: 0 - Caddy 1 - Tray 2 - Pop-Up 3 - Reserved 4 - Changer with individual replaceable disks 5 - Cartridge 6 - Reserved 7 - Reserved 15 - bit 0 - Separate channel adjustment bit 1 - Separate channel switch bit 2- Information about disk availability 16-17 - Maximum transfer speed in kilobytes 18 - ? 19 - Number of volume adjustment levels 20-21 - Buffer size in kilobytes 22-23 - Current baud rate ;---------may sometimes be missing------------ 24 - ? 25 - bit 0 - Digital out on rising/falling edge of BCKF signal bit 1 - LRCK indicates left/right channel bit 2 - data in LSB/MSB format bit 3 - ? bit 4 BCKs: 0 - 32 bit 5 | 1 - 16 bit 6 / 2 - 24 3 - 24 (I^2S) bit 7 - ? The length of each page may vary. Described hereonly those fields that are more or less standard. If all pages are requested (bits 0...5), then on the weekend the block will have one common header and sequentially arranged pages with their headings. 9.6. Setting General Settings The action of the command is similar to the previous one, with the only difference being that it does not return values, but writes them. Codes and You can see the page format from the previous description teams. ;#55 - Setting general parameters. DB #55 DB?; bit 1 - save to NVRAM (?) DB Page; required parameters page DS 4 DW Length; table length DS 3* 9.7. Operation error code ;#03 - Read drive status. DB #03 DS 11 Then you need to read 18 bytes of data and the 2nd byte will be the code operation errors. The CD-ROM returns the following errors: 0 - meaningless data 1 - repeated error 2 - no readiness 3 - environment error 4 - hardware error 5 - invalid request 6 - device maintenance 7 - data protection 11 - command interrupted 14 - incorrect comparison Unfortunately, I cannot give a complete description here the actions of each error, since I did not study them in detail. More complete information about the error can be obtained by looking at value 12 and 13 bytes. Description of these errors in EnglishI provide the language in the appendix at the end of the article. However, error handling when programming a CD-ROM has much more important than in programming Winchester. The fact is that when working with a CD CD-ROM returns an error quite often. But this is not always means that an error has occurred in the literal sense of the word, and may, for example, indicate that the CD-ROM is not ready transmit data due to insufficient rotation speed CD (that is, simply put, the disc is not yet unwinded). I will give an example from my immediate experience in writing a copier for CD-ROM: if some long while there is no access to the disk, it goes to low power consumption mode. Starts slower rotate. And when accessing the disk, for example when trying read data, it clears the BSY flag, but the speed The disk rotation is not yet sufficient to perform the operation. And The CD-ROM will return a "2 - not ready" error until until the disk rotation speed allows you to read data and transfer them to the computer. Actions when reading data (sectors) must have the following sequence: 1. We transmit a packet with a data read command (will be described me below). 2. We are waiting for the BSY busy flag to be removed. 3. Look at the 0th bit of the Status Register (if there is an error)4. If there is no error, continue reading the data. 5. We transmit packet "03". We read 18 bytes. Let's look at the error code. 6. If the code is 0 - “meaningless data”, then it is necessary Continue reading. Otherwise we go to the state errors. For more details, see Chapter 10 - "Example Reading data on the Spectrum." 9.8. Determining disk size ;#25 - Disk size in sectors. DB #25 DS 11 Then you need to read 8 bytes. The first four bytes are number of sectors on the current disk, and the next ones - size sectors (as a rule, does not depend on the disk and is equal to 2352). Let me remind you that the disk size can also be found from the TOC sector disk (chapter 11.1). 9.9. Audio information The following command allows you to obtain information related to to audio discs. The work of this team has not been studied by me, Therefore, I present its description with virtually no comments. Maybe you can get some useful information from here. ;#42 - mixed information (subchannel reading) DB #42 DB ScMsf ; 0/2 - type of address issuance (number sector or MSF) DB FullInfo; request option (full/short - 6th bit) DB Func ; subfunction (only for full request) DS 3 DW Length ; Table length DS 3 The command produces a block of the following information: +00 DW audio playback status:#00 - unknown or not supported #11 - Audio plays #12 - Audio costs #13 - Audio stopped at the end #14 - Door open or startup error #15 - Other +02 DW length of subsequent data (0 - none) Attention! +04 and further present if bit 40h is present in FullInfo and depend on Func. Func is not equal to 2 or 3: +04 DB 01 (subchannel data format = 1) +05 DB Ctrl/Addr +06 DB Track number. +07 DB Point or Index +08 DB 0 +09 DS 3 - MSF/SECTOR on disk +12 DB 0 +13 DS 3 - MSF/SECTOR on track --Subfunction 2-- (Get UPC code) +04 DB 2 (subchannel data format = 2) +05 DS 3 +08 DB #80 - UPC presence flag (if not, then UPC missing) +09 DS 12 - UPC code is stored here (6 digits in BCD code) +23 DS 3 - The position of something on the disk in MSF format --Subfunction 3-- (get ISRC code) +04 DB 03h (subchannel data format = 2) +05 DB Ctrl/Addr +06 DB Track number - not always used. +07 DB ? +08 DB #80 - presence flag (same as function 2) +09 DB further entry ISRC 9.10. Sector information This command creates a compromise between the two types addressing information on a CD: audio addressing (MFS) and sector addressing. At the input commands are given minutes/seconds/frames, and the output generates information aboutsector located in this location - its number and format. #44 - information about real position marks (Read HEADER) DB #44 DB SL - bit 2 - what to write to the output buffer (original sector number or read) DB 0 DS M,S,F - Sector number DB 0 DW Len - length of information output DS 3 The command returns a table of 8 bytes: +00 Sector format type (data mode) +01 0,0,0,0 +05 Sector address (M,F,S). Information is returned only if the CD was able to read a given sector and determine its type. 9.11. Track information This command has also not been studied by me, so I present it without comments or explanations. I used this command solely to find out which CD is in CD-ROM: audio or information. Subroutine allowing me to do this will be given by me at the end team descriptions. #43 - track information (READ TOC) DB #43h DB ScMsf - 0/2 type of address issuance (sector number or MSF) DS 4 DB BegTrk - initial track (from 1, 0 is replaced by 1) DW Length - Table length DB Func - information output options (0/40h/80h) DS 2 The command is informational and displays a table of tracks. Maximum table length = 8*#64+4 bytes or #64 (100) tracks. Func = #00 - get regular track table= #40 - get the session table = #80 - get a regular table in expanded format General table format: DW Len - length of subsequent fields in bytes DB BegTrk - first track DB EndTrk - last track D? - description of the tracks Description of tracks m.b. three formats: 1) 5 bytes per track (internal format, not external from CD issued): DB Ctrl/Addr - track type and flags DB Index - track index (number) DB Start (3 bytes) - address of the beginning of the track 2) 8 bytes per track (Func=0/#40): DB? DB Ctrl/Addr - track type and flags DB TrackNumber - track number DB? DB Start (4 bytes) - address of the beginning of the track 3) 11 bytes per track (Func = #80): DB Res1 DB Ctrl/Addr - track type DB Res2 DB Index - track index DB Res3 DB Res4 DB Res5 DB Start (4 bytes) - address of the beginning of the track The returned variables have the following values: Ctrl/Addr - track type Ctrl (low tetrad, single bits): 01 - there is pre-emphasis 02 - copying allowed 04 - data track 08 - 4 channels (not 2) Addr (high notebook, codes): 0 - no subchannel 1 - position is encoded in the subchannel 2 - UPC encoded in the subchannel3 - ISRC encoded in the subchannel other - reserved The most common codes: 14h - ROM 10h - audio Index - encoded in BCD and for a regular track is located in interval 01-99. Codes #A0 and above have a special meaning, they do not correspond to the physical tracks on the disc, but are service character - inform about the number of tracks, the beginning disk, end of disk, etc. Start - depending on the request, can be either a number sector, or sector address in MSF format. Audio disk management commands Since CD-ROMs were originally used for sound reproduction, and only later were they adapted for storage of information, therefore among the control commands The CD-ROM contains a large number of commands that work directly with audio disc format. These are the so-called audio tracks, or tracks. Typically, a CD-ROM has fairly independent management ability audio tracks. So, on the front panel of the CD-ROM there is audio output, where you can connect headphones or an amplifier, and button to switch tracks. Sound can also be recorded in digital form and read it by a computer (on an IBM PC this is handled by the sound card), but on the Spectrum, unfortunately, this cannot be done yet. Therefore, programmatically you canlimit yourself only to switching playback of the selected track, but the sound must be recorded through an amplifier or headphones only from the front panel of the CD-ROM or from a similar audio output on the rear panel. 9.12. Playback in blocks This command specifies the start of playback and the length of playback in blocks. Moreover, the number of blocks played 16-bit (maximum - 65535). #45 - play audio in blocks. DB #45 DB 0 DB (4)StartBlock - playback start block (-1 - from current position) DB 0 DW Length - number of blocks DS 3 This command differs from the previous one only in that the number of blocks played is set by 32-bit number. #0A5 - play audio in blocks. DB #A5 DB 0 DD StartBlock - playback start block (-1 - from current position). DD Length - number of blocks. DS 2 9.13. Playing audio in MSF This command specifies playback in MSF format. This way allows you to set a very precise (down to a fraction of a second) location start of playback and playback time. Table Track locations in this format can be obtained using commands "#43 - track information" (chapter 9.11). #47 - play audio in MSF. DB #47 DS 2 DB M,S,F - beginning of the segment (FF:FF:FF - current position)DB M,S,F - end of segment DS 3 9.14. Stop/resume playback This command is used to stop/resume playback music. #4B - Start/stop audio. DB #4B DS 7 DB Func DS 3 Func=0 - stop playing. Func=1 - continue playing. 9.15. Stop playback This command is very simple and serves only one purpose - stop playing the audio track. Besides, she doesn't requires additional parameters. #4E - stop playing. DB #4e DS 11 Read Data Commands There are two commands for reading data. One of them allows read data in specific sectors, and another in parameters MSF (described above). If reading in MSF is relevant for audio discs, when we want to accurately read the audio track to convert it, for example, into a file (.wav or .mp3, The minimum size of such a file is several megabytes, for Spectrum is irrelevant). Although you can write a program playing back short areas from an audio disc for then converting them into samples for General Sound. Then it is convenient to read the data in MSF. Reading in sectors are just convenient for reading files (since all file parameters are indicated in sectors). Below I am I will give a description of two reading options and an example for readingsectors on the Spectrum. 9.16. Reading data in MFS #B9 - Reading data in MSF. DB #B9 DB Fmt can be = 00h any format is suitable 08h regular CD (Yellow book) 10h varieties 14h/ Green Book. DB 0 DB M,S,F start reading DB M,S,F end of reading DB Flg flags of the readable part of the sector: 01h three 02h unused (?) 04h bit 08h EDC/Zero/ECC 10h main sector body (data) 20h sector address descriptor (head) 40h subchannel data (sub) 80h initial sync bytes (sync) Only those parts of sectors are transmitted for which bits are set. Transferable parts sectors must go consecutively, without gaps. DB 0 always d.b. =0, otherwise error DB 0 If in this command the read start address matches the address end of reading, then positioning occurs on the specified position and reading is tested. No data is transferred. 9.17. Reading data in sectors #BE - Read data in sectors. DB #BE DB Fmt - reading format (as in #B9).DB Sec - start reading - 4 bytes. (uses 24 bits only) DB 0 DW ScNum - Number of sectors DB Flg - flags of the readable piece of the sector (as in #B9) DB 0 - always d.b. =0, otherwise error. DB 0 The command is completely similar to command #B9 - “Read data in MFS", with the exception of setting the addresses of the reading area in sectors. 10. EXAMPLE OF READING DATA ON THE SPECTRUM Below I will give an example of a subroutine for reading sectors on Spectrum. Before calling it, you need to set the values in AP_BE package (reading data in sectors). An example of this package you see in front of you. SECTOR - reading sector. SECTORS - number of sectors to read (unfortunately, according to for unknown reasons when trying to count more than one sector Errors occur in the received data. Therefore I advise you read one sector at a time and do not change this variable). AP_BE DB #BE,#00 SECTOR DB #00,#00,#00,#1F DB 0 SECTORS DB #00,#01 DB #10 DB 0.0 And the reading subroutine itself: ;IN: [HL] - address to read. LOAD_SECTOR PUSH HL CALL NO_BSY LD HL,AP_00 CALL SEND_ATAPI LD HL,AP_BE CALL SEND_ATAPI LOAD_SECTOR_CALL NO_BSY CALL NO_ERROR JP C,ERROR CALL WAIT_DRQ POP HL LD B,8 LOAD_SECTOR1