DISK DRIVE ADDITIONS FOR MORROW MICRODECISION 2 I recently added two additional disk drives to my Morrow Microdecision 2 computer. These notes describe the method used. While these instructions worked on my computer, I make no guarantee that they will work for your system. Please be aware that a mistake might void your warranty. THE COMPUTER: Morrow has a number of different configurations in use in the MD series. The system described here has Shugart SA200 disk drives and a Rev. 1.1 motherboard. This configuration has 2 serial ports, no parallel port, and an expansion disk connector at the rear of the computer. Fig. 1: MD2 REAR VIEW +-------------------------------------------------------------+ | +---+ | | | o | | | | n | This is it! | | +---+ | | | +---+ V | | | A | 34 2 | | | / | +----------+ +---------+ +----------+ | | | C | | DRIVE EXP| | P/M PORT| | TERMINAL | | +-------------------------------------------------------------+ Note the numbers above the drive expansion connector in Figure 1. They refer to the pins on the edge connector. SOFTWARE: Before you make any hardware changes, make the needed changes to your software. (While you know everything still works!) You'll have to set up your CP/M to recognize the third and fourth drives. To do so, place your CP/M distribution disk in drive A and boot the system. Follow the prompts. When it asks for the number of drives, type '4'. When you get to the main menu, type ESC to exit. Place your CP/M distribution disk in a safe place. Boot your new CP/M working disk. You should be able to access Drives A and B as before. If this works, try accessing drive E. This should act as a virtual drive. (You'll be requested to remove the disk from Drive A, and insert the disk for Drive E .) Finally, try accessing Drive C and Drive D. For either of these drives, you should receive an error message inviting you to abort, retry, or ignore the error. If you get the correct responses from the software, you can then use SYSGEN to move copies of the system to other disks. Make sure that you have 4 formatted disks on hand for testing. .cp 5 HARDWARE: To add the two drives, you will need two Shugart SA200 drives (with manual), a dual horizontal disk drive cabinet with power supply, a 34 conductor cable with edge connectors, wire, solder, and hand tools. Begin with the cable to connect the drives to the computer's expansion drive connector. You can buy it, or make it yourself. If you make one, you will need a length of 34 connector ribbon cable and three matching edge connectors. Assemble the cable with one connector at one end, and the other two connectors spaced about a foot apart at the other end. If the connectors are the slip-on style, be sure to install the connector marked 'C' before installing the other connectors. (Considerable pressure may be needed to insure good contact between the cable and the connectors. A rubber mallet or vise may be useful.) Fig. 2: CABLE LAYOUT +-+ 2 2 +-+ 2 +-+ |E|============================================| |==========| | |X|============================================|C|==========|D| |P|============================================| |==========| | | |============================================| |==========| | +-+ 34 34 +-+ 34 +-+ Next prepare the drives. Referring to Fig. 3, locate the terminating resistor pack (T in Fig. 3) and remove it. Locate the Disk Select jumper and place the jumper at DS1. This will be Drive C. Preparing Drive D is a bit more complicated. Some soldering will be required, so plug in your soldering iron. Leave the terminating resistor pack in place. Place a jumper at DS2. Now refer to Fig. 3 and locate edge connector J2. The pins on this connector are odd numbered on the bottom, and even numbered on the top. Viewed from the front of the drive, pin 2 is on the right, and pin 34 is on the left. Carefully solder a small piece of wire from pin 4 to pin 12. It is important to solder the wire on the drive side of the pins, so that the edge connector can still slide over the pins. This jumper connects +5VDC to the Drive Select 2 input. (Some documentation from Morrow indicates that pin 2 and pin 12 should be connected, but that did not work in this case.) .CP5 Fig. 3: PARTIAL TOP REAR VIEW OF SA200 J2 J1 +--------------- --+ +------+ |34 2| | | +-----+ +---+ | | T +-----+ DS 1234 | | +-----+ :::: | | | +-----------------+ | Next install the drives in the cabinet. The Shugart SA200's are 2/3 height drives that are to be installed horizontally. They may be mounted side - by - side, as in the MD2, or stacked. Important: Install the drives horizontally, with the printed circuit boards on the top. If the printed circuit boards are mounted underneath, the drives may be damaged. Connect the power supply to J1 of each drive, and perform the initial checks listed in the SA200 manual. Power up the drives for the blue smoke test. If the drives are functioning properly at this point, install the cable from the computer to the drives. Take care that pin 2 on the computer is connected to pin 2 on the drives! Power up the entire system, and if it passes the blue smoke test, try Drive A and Drive B to make sure that they still work correctly. Then try Drive C and Drive D. You should be able to read the directory for all 4 disks. If things are still going well, try to format the disks in Drive C and Drive D. Use PIP to transfer files from A and B to C and D. If that is successful, check to insure that disks written on C and D can be read on A and B. With care, you now have a functioning four drive MD2. If you have problems, review the entire procedure. Pay particular attention to the disk connector cable; it is the "weak link" in the setup. 25-Nov-83 Stan Young POB 8 Lilburn, GA 30247 Note: MicroDecision (R) is a product of Morrow Designs, Inc. CP/M 2.2 (R) is an operating system developed by Digital Research, Inc. ecision (R) is a produ