Burke & Burke App. Note 1 December 3, 1987 COPR. 1987 BY BURKE & BURKE Hi! My name is Chris Burke, and I designed the CoCo XT hard disk interface sold by Burke & Burke. This article provides general information on setting up a hard disk system based on the Burke & Burke CoCo XT and CoCo XT-RTC hard disk interfaces. Much of this information is also pertinent to other CoCo hard disk systems. 1.1 About the CoCo XT The CoCo XT interfaces a standard PC compatible hard disk drive and controller to any Color Computer. Burke & Burke chose this type of hard disk system because it offers a combination of high quality, high performance and low price. We also offer the CoCo XT-RTC, which provides a battery-powered real-time clock / calendar in addition to all of the features of the CoCo XT. The battery provides over 10 years of reliable clock operation, and can be easily replaced by the user. In this article, the name CoCo XT will be used to refer to both the CoCo XT itself, and the CoCo XT-RTC. The CoCo XT uses the same type of hard disk controller that is used in many "clone" personal computers. The controller includes a 2048 character disk buffer, which eliminates the need to halt the computer while accessing the hard disk (this feature is sometimes refered to as DMA -- Direct Memory Access). The CoCo XT is a hard disk interface. The metal housing of the CoCo XT holds both the Burke & Burke interface board and a hard disk controller board that you supply. 1.2 Equipment Requirements In order to use the CoCo XT, you must have the following equipment and software (not included): - CoCo, Multi-PAK Interface, and Floppy Disk System - 1 or 2 suitable hard disk drives - Suitable hard disk controller and cables - Hard disk cabinet and power supply - Burke & Burke XT-ROM (optional -- boots OS9 from hard disk) - Burke & Burke HYPER-IO software package (optional -- - 1-1 - Burke & Burke App. Note 1 December 3, 1987 COPR. 1987 BY BURKE & BURKE allows you to use hard drive with RS-DOS Disk BASIC) - OS9 Level I or Level II operating system (optional) Typically, 20 Meg hard drives are available mail-order for about $275 including the controller and cables (10 meg systems are about $150). If you purchase the controller and cables seperately, they will cost about $75. Hard disk cabinets with built-in power supplies are available for around $80. The best place to look for mail-order equipment deals is in a monthly magazine called COMPUTER SHOPPER. This magazine costs about $3.00 per issue, but the 400+ pages of ads are well worth the money. Four hardware vendors that we and our customers have dealt with successfully are: LUCKY COMPUTERS (Richardson, TX) -- Controllers TIMELINE INC. (Gardena, CA) -- Drives and Controllers HARDTIMES (San Jose, CA) -- Drives and Cabinets WALKER ELECTRONICS (Dallas, TX) -- Cabinets 1.3 Computer and Multi-PAK Information The CoCo XT works with the CoCo 1, CoCo 2, or CoCo 3. You will need at least 64K of memory to use the interface from either BASIC or OS9. The hard disk can be shared between OS9 and BASIC if desired, but individual files cannot be transferred between OS9 and BASIC without special software (currently under development by Burke & Burke). You must have a Multi-PAK or compatible expansion interface in order to use the CoCo XT. The CoCo XT installs in slot 3 of the Multi- PAK, in accordance with Tandy's hard disk standard. Although a configured hard disk system can run without any floppy drives, you will need a floppy disk controller and at least 1 floppy drive in order to set up your system. The floppy disk controller may use any version of Disk Extended Color BASIC (RS-DOS). Other DOS programs are not supported. 1.4 Hard Disk Drive Information Most hard disk drives used in personal computers provide either an ST-412/ST-506 interface or an on-board SCSI/SASI controller. Neither of these interfaces is directly compatible with either a Color Computer (or with a PC, for that matter). The ST-412/ST-506 interface requires a suitable hard disk controller; the SCSI/SASI interface requires a SCSI/SASI controller in order to communicate with the host computer. The Burke & Burke interface is designed to work with hard drives that provide an ST-506/ST-412 interface. This type of drive is both more common and less expensive than a SCSI/SASI drive, and controllers - 1-2 - Burke & Burke App. Note 1 December 3, 1987 COPR. 1987 BY BURKE & BURKE for this type of drive are both abundant and economical (about $65 mail-order). The storage capacity of a hard drive is often described in "mega- bytes". A megbyte is simply a million characters, so a 20 Meg hard disk holds about 20,000,000 characters. That's equivalent to over 1,000 pages of text! The hard drive is organized into a number of "heads", each of which is further divided into "tracks". The tracks are divided into 256 or 512 character "sectors", much like a floppy disk. The number of heads on a hard drive normally ranges from 2-16. The number of tracks is usually between 150 and 1024. The maximum number of sectors per track depends how many characters there are per sector, and also on something called the "encoding method". There are 2 commonly used encoding methods: MFM and RLL. The first method, MFM, is used on both floppy disks and hard disks. This method provides 32 or more (256 byte) sectors per track. The RLL method is a newer technique that requires a special disk drive -- it squeezes 48 or more sectors into every track. Some hard disk controllers only support a maximum of 8 heads. If you are buying a drive with more than 8 heads, you must be sure to get a suitable controller. 1.5 Hard Disk Controller Information Hard disk controllers used with the Burke & Burke system must have both a 62-contact edge connector and the ST-412/ST-506 interface. The edge connector plugs directly into the 62 position socket on the CoCo XT interface card; the combined interface card and controller then plug directly into the Multi-PAK's 40 position socket. The height of the combined interface card and hard disk controller is almost exactly the same as the height of the original Tandy floppy disk controller. Not all PC-compatible hard disk controllers are alike, and some will not work with the CoCo XT. The hard disk support software, and the mounting screws in the interface housing, are optimized for use with particular hard disk controllers. Two controllers that work well with the CoCo XT hard disk interface are: - Western Digital WD1002A-WX1 (MFM) - Western Digital WD1002S-27X (RLL) The ST-412/ST-506 interface consists of a 34 contact connector and one or more 20 contact connectors. The 34 contact connector mates with a cable that is "daisy chained" to all hard drives in your system -- much like the 34 conductor cable used with floppy drives. The 20 contact connector mates with a cable that is unique for each drive. A hard disk controller that supports 2 hard drives will have one 34 contact connector and two 20 contact connectors. - 1-3 - Burke & Burke App. Note 1 December 3, 1987 COPR. 1987 BY BURKE & BURKE All of the CoCo XT compatible hard disk controllers include a 2K disk buffer. The hard disk controller reads from or writes to this buffer independent of what the CoCo is doing. Your CoCo does not need to slow down or "HALT" during hard disk I/O, because the hard disk controller takes care of all critical timing. All of the CoCo XT compatible hard disk controllers also include a "BIOS ROM". This ROM or EPROM normally contains software that tells a PC "clone" computer how to access the hard disk. Since this software is not needed in CoCo hard disk systems, the CoCo XT allows your Color Computer to execute instructions out of a custom EPROM that you install in the BIOS ROM socket (one such EPROM is Burke & Burke's XT-ROM, which automatically boots OS9 from your hard disk at power-up). The hard disk controller stores and retrieves information from the hard disk 512 bytes at a time. Burke & Burke's interface software automatically translates between this 512 byte sector size and the 256 byte sectors used by OS9 and Disk BASIC. Although most hard disk controllers are capable of operating in an interrupt driven mode, Burke & Burke have maximized both the performance and ease of installation of the CoCo XT by not using interrupts in our interface. This allows you to use the CoCo XT in conjunction with other interrupt driven devices, such as an RS-232 PAK or a modem PAK, without having to make hardware modifications to your equipment. 1.6 Hard Disk Power Supply Information A hard disk uses much more power than the CoCo can supply. A lot of this power goes to run the motor that spins the disk's platters at 3,600 RPM, especially when the motor is just starting up. Typical hard disks need at least 3 Amps at 12 volts and 1 Amp at 5 volts to operate correctly. Some hard disks need as much as 5 Amps at 12 volts when they first start up. Most floppy disk power supplies provide only about 1.5 Amps at 12 volts. Burke & Burke does not recommend using a floppy disk power supply to run a hard disk. Power supply capabilities are often expressed in Watts. Your hard disk power supply should be rated for at least 40 Watts in order to provide the voltages and currents listed above. If you have 2 hard disks, you could need twice this power. 1.7 CoCo XT Interface Board Information This circuit board is the primary hardware component of the CoCo XT. It converts the CoCo's 40 pin expansion bus into a 62 pin bus suitable for driving PC compatible hard disk controllers. Both the CoCo XT and CoCo XT-RTC versions of this circuit board include bus conversion logic. The CoCo XT-RTC version of this board - 1-4 - Burke & Burke App. Note 1 December 3, 1987 COPR. 1987 BY BURKE & BURKE also includes a battery holder, clock circuit, and quartz crystal. The hard disk controller and real-time clock are selected by a low on the SCS* pin and a simultaneous high on the A4 pin. This allows the CoCo to access these devices in the address range $FF50- $FF5F when used in conjunction with a Multi-PAK interface. The controller's BIOS ROM socket is selected by a low on the CTS* pin. This allows the CoCo to access XT-ROM or other custom ROM's in the address range $C000-$FFFF. Note, however, that several of the address lines driving this EPROM are inverted by the CoCo XT interface board. Special equipment is needed to create a ROM that is compatible with the CoCo XT, and most "off-the-shelf" DOS EPROMs are incompatible. The interface board shorts the Q and CART* signals together in order to "kick start" programs stored in the BIOS ROM socket. This signal is used only during power-up, and does not effect normal operation of the CoCo. If not desired, the "kick start" feature can be permanently disabled by making one plating cut on the interface board. The interface board is about 1.5" high, and plugs into slot 3 of the Tandy Multi-PAK interface. 1.8 Software Information Burke & Burke provides several software packages that support the CoCo XT hard disk interface. The CoCo XT package includes all of the software needed to use one or two identical hard disks under Level I or Level II OS9. The CoCo XT release disk also includes an OS9 hard disk back-up utility and a hard disk driver routine (XT.DR) that can be used in conjunction with Burke & Burke's HYPER-I/O program to allow you to share your hard drives between OS9 and Disk BASIC. The CoCo XT-RTC package adds real-time clock support software to the CoCo XT. This software includes OS9 utilities that transfer the correct date and the time of day from the real-time clock to the OS9 system clock automatically at power-up. You can also set the real- time clock from the system clock at any time. A machine language subroutine library is provided for those who wish to access the real- time clock from Disk BASIC or HYPER-I/O. If you want to use the hard drive with Disk BASIC, you must use Burke & Burke's HYPER-I/O package. HYPER-I/O is *not* a hard disk DOS; it is a "DOS overlay" that allows you to install device drivers and device descriptors in Tandy's Disk BASIC. One such device driver is the XT.DR hard disk driver provided in the CoCo XT release disk, but instructions are provided for writing custom device drivers if you so desire. For example, HYPER-I/O will also support hard drive systems from Tandy and other vendors with suitable drivers -- contact Burke & Burke for further information. - 1-5 - Burke & Burke App. Note 1 December 3, 1987 COPR. 1987 BY BURKE & BURKE While HYPER-I/O provides total compatibility with BASIC programs and most machine language subroutines, the current release of HYPER-I/O (1.4) is not compatible with RS-DOS machine language programs that bypass the Disk BASIC ROMs. The next release of HYPER-I/O, version 2.0, will provide greatly increased compatiblity with this type of machine language program. HYPER-I/O supports any size and combination of floppy disks, and is a prerequisite for HYPER-III, our RAM disk / printer spooler package for the CoCo 3. When using a hard disk with HYPER-I/O, there is no need to divide the disk into rigid OS9 and BASIC zones. OS9 files and HYPER-I/O files are stored on the hard disk in different formats, but the HYPER-I/O format conforms to OS9 requirements. This means that you can add either HYPER-I/O or OS9, or change the amount of hard disk storage allocated to either, at any time without reformating your hard disk. HYPER-I/O also allows you to use two hard disks of the same or different sizes if you so desire. HYPER-I/O stores information on the hard disk in regions called "MSA's" (Mass Storage Areas). To OS9, each MSA looks like a large data file; to HYPER-I/O, an MSA looks like an image of a floppy disk. Many different sizes of MSA are allowed, including standard 35 track floppy disk emulation and emulation of double-sided, 160 track super-floppies. Several different sizes can be mixed on the same hard disk. You can create up to 200 MSA's distributed across one or two hard disks. 1.9 Summary The CoCo XT hard disk interface from Burke & Burke allows you to put together an inexpensive CoCo hard disk system that works with both Disk BASIC and OS9. The components that you need to assemble this system are: - CoCo, Multi-PAK Interface, and Floppy Disk System - CoCo XT or CoCo XT-RTC hard disk interface - 1 or 2 suitable hard disk drives - Suitable hard disk controller and cables - Hard disk cabinet and power supply The drives, controller, cables, and power supply are available through a number of vendors that advertise in COMPUTER SHOPPER. For a 20 Meg system, you can obtain these items for about $350; a 10 Meg system would be about $230. These prices do not include the CoCo XT or CoCo XT-RTC interface, or the Color Computer, Multi-PAK, and Floppy Disk System. Christopher J. Burke - 1-6 - *2Burke & Burke App. Note 2 December 12, 1987 COPR. 1987 BY BURKE & BURKE This article provides some helpful hints and errata for setting up and using Burke & Burke products. CoCo XT and CoCo XT-RTC ----------------------- In order to increase reliabilty of operation, Burke & Burke has changed the way in which the CoCo XT interface is used with an RLL hard disk controller. To use an RLL controller, you must now specify 32 sectors per track, multiply the number of tracks per surface by 1.5, and INSTALL JUMPER W9 ON THE HARD DISK CONTROLLER. One of the most popular drives used with an RLL controller is the ST-238. As an example, here are the new and old parameters for an ST-238 hard drive: Parameter Old Value New Value --------- --------- --------- Heads 4 4 Tracks 615 922 Sectors 48 32 Note that the ST-238 does not *REALLY* have 922 tracks, but the controller automatically translates sector numbers to make the drive look this way when W9 is installed. From now on, all types of drives used with the CoCo XT will specify 32 sectors / track. Please disregard references to 48 sector tracks in the instruction manual. If you have already formatted your RLL hard disk using 48 sectors per track in the device descriptor, you should convert to the new format for 2 reasons: 1) Increased reliability of operation 2) Compatibility with future software releases The procedure for converting to the new format is: 1) Use HDB to back-up your hard disk to floppies. 2) Modify your device descriptors and install jumper W9 on the hard disk controller. 3) Reformat the hard disk using the new configuration. 4) Use HDR to restore your data to the hard disk. You may experience difficulty using HYPER-I/O to format your hard drive (RLL or normal). There is a bug in the XTFMT utility that causes it to get the drive characteristics wrong. If you have this problem, here are 2 solutions: 1) Use the OS9 FORMAT utility to format the drive; you will then be able to use it from both OS9 and HYPER-I/O. 2) Contact Burke & Burke at (312) 397-2898 for a free - 2-1 -*0 *2Burke & Burke App. Note 2 December 12, 1987 COPR. 1987 BY BURKE & BURKE CoCo XT Version 1.4.1 release disk, which has a fixed version of XTFMT that allows you to correctly format the drive from HYPER-I/O. Look for Version 2.0 around the beginning of the year. This version will allow you to use 2 hard drives of different sizes under OS9; it will also use less memory and less processor time. The RTC command on the Version 1.4 release disk is actually a duplicate of the CLKGET utility. This has been corrected on the Version 1.4.1 release disk, which includes the actual RTC utility. HYPER-I/O --------- Although HYPER-I/O is compatible with all BASIC programs and most machine language subroutines, many machine language programs are incompatible with the current version (1.4) of HYPER-I/O. Burke & Burke is developing Version 2.0 of HYPER-I/O to provide increased compatibilitachine language programs. Version 2.0 will differ from Version 1.4, in that MSA's will be MSA's will be limited to at most 68 granules, with up to 64 sectors per granule (1.1 Megabytes each). This means that if you are currently using larger MSA's, you will have to copy your files off of these MSA's, use Version 1.4 to delete the big MSA's, create smaller MSA's compatible with Version 2.0, and then copy the files back to the new MSA's. YOU ONLY NEED TO DO THIS IF YOU ARE USING MSA'S WITH MORE THAN 68 GRANULES. Version 2.0 will provide a few other handy enhancements, like a utility to transfer files between MSA's and the OS9 file system. Also, the Version 2.0 HDFMT utility allows you to do a "logical verify" when formatting the hard disk, in order to prevent HYPER- I/O from storing data in defective areas of the hard disk. New hard disk drivers that allow you to use HYPER-I/O with other vendors' hard disk interfaces (Tandy, LR, Disto) will be available from Burke & Burke as seperate packages in the near future. Burke & Burke is currently investigating reports of a bug in the BACKUP command of HYPER-I/O. If you have experienced difficulty with this command, please contact Burke & Burke. XT-ROM ------ When using XT-ROM with an RLL controller, please disregard the manual's instructions to install a jumper on S1-8. As mentioned above, you should use 32 sectors per track for *ALL* types of hard disks, including RLL controllers. S1-8, when installed, was used to specify 48 sectors per track and is now OBSOLETE. - 2-2 -*0 *2Burke & Burke App. Note 2 December 12, 1987 COPR. 1987 BY BURKE & BURKE XT-ROM automatically senses whether it is running in a CoCo 2 or a CoCo 3. This information is displayed in the center of the bottom line of the screen, as either "C2" or "C3". There is a bug in the 1.0 release of XT-ROM that causes it to mistake a CoCo 3 for a CoCo 2 under certain conditions. This will prevent the boot procedure from working. You can correct this problem by breaking the connection between pins 7 & 8 of the 40 pin edge connector on your CoCo XT interface board. With the 40 pin connector facing you, and the component side up, pin 7 is the 4th pin from the left on the component side; pin 8 is directly opposite this pin on the solder side. To break the connection, simply ream out the feedthrough hole in the edge finger with an X-ACTO knife. This modification will not effect unit operation in any way, and does not invalidate your Warranty. There is also a bug in the "fallback" floppy disk boot routine, which causes the floppy boot to fail. The hard disk boot does work, though, and that's what XT-ROM is really for. If you are installing XT-ROM as a "piggy-back" on the BIOS ROM, you may need to add a 4.7K pull-up resistor (or just a wire) between pins 20 and 28 of the *ORIGINAL* BIOS ROM after clipping off pin 20 as shown in the instructions. Note that this resistor connects to pin 20 of the BIOS ROM, and not to pin 20 of XT-ROM. The best solution is to remove the BIOS ROM and install the 28 pin IC socket supplied with XT-ROM. The current release of XT-ROM does not allow some hard disks enough time to come up to speed before attempting the boot. This causes XT-ROM to abort the hard disk boot and attempt a floppy boot. As a temporary work around, you can either 1) Turn on your hard disk about 10 seconds before turning on the CoCo -- or -- 2) Depress RESET during the floppy boot to restart the boot process. All of these bugs will be fixed in release 1.1, which will be shipped inary (or maybe late December). If you already own Version 1.0, you will automatically receive a free upgrade to Version 1.1. WILD! ----- Version 1.0 of the WILD! OS9 wildcard utility has a few quirks: 1) Options must be given in lower case. 2) Upper and lower case filenames are unique. 3) It won't find memory resident commands; WILD! always goes out to disk and tries to LOAD the command. 4) If you use different source and destination pattern types the program sometimes gets confused and generates funny looking filenames. - 2-3 -*0 *2Burke & Burke App. Note 2 December 12, 1987 COPR. 1987 BY BURKE & BURKE 5) If you specify a NULL destination file name, WILD! will change the name of the file to "nothing" -- the file will be lost. Burke & Burke has just released Version 1.1 of WILD!, which fixes these bugs and also includes an MV utility and a TRASH utility. If you already own Version 1.0, you will automatically receive a free upgrade to Version 1.1. Christopher J. Burke Burke & Burke - 2-4 -*0 Burke & Burke App. Note 3 January 31, 1988 COPR. 1988 BY BURKE & BURKE This article provides some helpful hints and errata for setting up and using Burke & Burke products. CoCo XT and CoCo XT-RTC ----------------------- We have found that certain RLL hard disk controllers cannot be configured for 32 sectors per track. One such controller is the Adaptec 2072, which is often sold with the ST-238R hard drive. When using this type of controller, you should set up your device descriptors for 48 sectors per track, with the normal number of tracks (e.g. 612 for the ST-238R). The Adaptec operates very reliably in this mode. Burke & Burke continues to recommend that, when using the Western Digital WD1002-27X controller, you install W9 and set up descriptors that indicate 32 sectors per track and 1.5 times the normal number of tracks (e.g. 918 for the ST-238R). Western Digital has recently changed the mechanical design of their hard disk controllers, moving the mounting holes and eliminating jumper bank S1. One such controller is the Western Digital WD1002A-WX1. You must make a slight modification to the CoCo XT housing in order to mount the 'A-WX1: one of the mounting screws must be removed, and the threaded insert must be snapped off of the board with a pliers. You must also file a small notch in the controller board, which does not effect its operation in any way. Contact Burke & Burke for further information if you need to use this type of controller. Version 2.0 drivers should be available from Burke & Burke mid-February. These drivers provide several advanced features: * Improved error reporting * Supports hard disk controller in any slot * PARK works correctly; DDMAKER allows user to input park track * Supports up to 2 hard drives, which may be different sizes XT-ROM ------ When using a hard disk controller that does not provide jumper bank S1, you must hard-code your drive parameters into the BOOT module. To accomplish this under Level 2 OS9: 1) Use PATCH to install the hard disk BOOT module as explained in the XT-ROM installation guide. 2) Using DEBUG (Level 1 Debug will work if you do not have the Developer's Pak): - 3-1 - Burke & Burke App. Note 3 January 31, 1988 COPR. 1988 BY BURKE & BURKE DB:l BOOT XXXX DB:. .+140 XXXX 06 DB:= h ('h' is the number of heads on your drive) XXXX YY DB: .+1B XXXX 2B DB:= zz (zz is '20' for 32 sectors, '21' for 48 sectors) XXXX YY DB:$fix BOOT DB:q The current release of XT-ROM is 1.20. Christopher J. Burke Burke & Burke - 3-2 -