North Star MDS-A Manual 

Contents Parts List . . . . . . . . . . . • 3 Warranty • . . . . . . . . . . . • • . 6 Theory of Operation . . . . . • . 7 Assembly and Check-out . • . . . . . . . . 15 System Integration .......•.. 24 Drawings . . . . . . . . . . . .. .• 27 Copyright 1977, North Star Computers, Inc. ...

Contents • • • • • 3 . • • • •. ••. 6 Parts List • • • • • Warranty • • • • • • Theory of Operation Assembly and Check-out System Integration Drawings • • • • • • • • • . . • . . .. 7 . . . • . . . . 15 . . . . .. .. 24 . . • . . . . . • . 27 Copyright 1977, North Star Computers, Inc. ...

else. 2. Do NOT insert or remove the MDS controller from the computer while the power is turned on. 3. Do NOT insert or remove IC's from the board while the power is turned on. 4. Be sure the +5 volt regulator is generating +5 volt output voltage before installing any IC·s. 5. Be careful to insert all IC's in correct positions and with correct orientation. 6. Do NOT connect or disconn ...

disk ~rive, Shugart SA-400 ribbon cable assembly diskette, blank 1 1 1 1 1 1 1 1 1 1 diskette, pre-recorded with software MDS manual DOS manual BASIC manual OEM manual MDS controller with parts power board with parts MDS CONTROLLER PARTS 1 printed cirCuit board (5" x 10") 1 bo1t,6-32x1/2" 1 lock washer 1 nut, 6-32 1 heat sink, 61018-14 1 5 volt regulator, 7805 or 340T-5 1 crystal, 4MHz 23 16-pin low profile IC sockets 24 14-pin ...

33pf dipped mica .047uf ceramic disc 680 ohm 150 ohm 2.2 K Cl C2 C3 C4 by-pass Rl,R2 R3 , R4 , R5 ,R6 R7,R8 MDS POWER BOARD PARTS 1 1 1 2 1 1 1 1 3 3 3 1 4 1 1 2 2 printed circuit board, 3" x 51/2" 1% resistor, RN55D 232 ohm 1% resistor, RN55D 1 .. 96 K capacitors, .047uf ceramic disc regulator, 7805 or 340T-5 regulator, LM317K heat sink, 295-2 heat sink, 690-3-B bol ...

I I I I I I I I 2 2 2 2 2 I 115v cord set, 8 feet strain relief bushing fuse holder fuse, IA 3AG toggle switch transformer capacitor, 3000uf30wvdc electrolytic capacitor, 2500uf 15wvdc electrolytic rectifier diodes, MR501 3A rectifier diodes, IN4002 IA bolts, 6-32xl/2" lock washers nuts, 6-32 hook-up wire CABINET PARTS (MDS-CAB option) I I 4 4 6 5 cabinet base plate cabinet cover stick-on rubber feet 6-32 flat head screws ...

parts and workmanship of this product to be free of defects for a period of: a) 90 days from date of purchase, if purchased in kit form, or, b) 180 days from date of purchase, if purchased assembled. If such defects occur, North Star Computers, Inc. will repair the defect at no cost to the purchaser. This warranty does not extend ~ defects resulting from improper use or assembly by ...

The North Star MICRO-DISK System (MDS) controller is an . integrated system of hardware and software. It is designed specifically to provide a complete, compact and economic~l disk drive controller for use with S-100 bus 8080 or Z80microcomputer systems •. HARDWARE The MDS controller is implemented entirely from medium and small scale TTL integrated circuits and PROM memory. The entire controller fits on. a single 5 1 x10" printed cir ...

Encoder Controls to Disk Controls from Disk Data' to Disk MDS Controller Block Diagram North Star MICRO-DISK System (to 8(80) 8 8;"bit shift reg Data Separator Data from Disk 8 ...

Controller software (8080 or Z80 machine code) is stored, in part, in two on-board 4x256 bit bipolar PROMs. These PROMs provide 256 bytes of memory. Replacihg these PROMs with pin compatible 4x512 PROMs would provide 512 bytes of on-board program. The 8 low order address bits address the PROMs. The. PROM outputs are driven onto the Data Input Bu~. 5. Clock Circuit. The crystal. controlled clock circuit (SA, 58, 4A, 6A) provides 2 MHz cloc ...

read references to addresses within a particular IK byte block of the CPU address space. The IK byte block subdivides into four cases. In all cases the high order 6 address bits (8S) are used to determine if the IK block is addressed (i.e. the controller board is selected). The next two bits determine the subcase and the use of the low order eight bits depends on the subcase. CASE Ii) CASE I ...

The commands are specified by the 8 low order address bits. MO if 1 then turn disk drive motors on if they are off and reset auto-motor-off timer. If 0 then no action. RD If one then read a data byte from the read shft register and gate it onto the Data Input Bus. Hang the CPU until the read shift register is full. If zero then gate status bits onto the Data Input Bus. BST If one then gate B- ...

the Data Input Bus. A-Status 8-Status SP ] SF Sector Flag. Indicates a sector hole was detected. wN Window Flag. Indicates if the status byte was read during the window. MO Motor On. Indicates that the motors are on. WRT Write. Indicates that controller is ready to receive data bytes .to write. Bey Body. Indicates that a sync char was found and that data bytes can now be read. WP Write P ...

Each track is divided into 10 sectors. The rotational position of the beginning of the sectors is marked by sector holes in the diskette. Each sector is recorded using the following format. This ihformation is recorded starting about 96 microseconds after the sector hole is detected. Zeros 16 bytes Sync Char(FB) 1 byte Data 256 bytes Check Char 1 byte 274 bytes The check character is computed iteratively by ...

If not then repeat this step. 5. If the data write case then a. issue start write command. b. wait for write status bit. c. write 15 bytes of zeros. d. write the sync character (FB hex). e. write 256 bytes of data from RAM while computing the cyclic check character. f. write the check character. g. if more blocks to write on the same track then wait until the next sector pulse and repeat from step a, otherwi ...

SOLDERING TIPS For best results use a 15 watt soldering iron or an iron with a temperature regulated tip. The tip should be no wider than the solder pads on the printed circuit board. Use only a fine gauge, rosin core solder. When soldering, keep the soldering iron tip on the pad just long enough for the solder to completely flow. If the solder does not draw up the wire then more solder is required. Use less solder if it ...

indicated by the silk screen legend. The hole spacing for all th~ resistors is .5 inches. Rl 680 ohm blue-gray-brown R2 680 ohm blue-gray-brown R3 150 ohm brown-green-brown R4 150 ohm brown-green-brown R5 150 ohm brown-green-brown R6 150 ohm brown-green-brown R7 2.2 K red-red-red R8 2.2 K red-red-red 4. Install and solder the 22 capacitors in the locations indicated by the silk screen legend. The e ...

The right angle bent pins should be inserted into the PC board and the straight ends of the pins should be pointing toward the top of the board. The board is now completely assembled except for inserting the IC's. Proceed with the check-out procedure. CONTROLLER CHECK-OUT PROCEDURE The following procedure should be followed for systematically checking-out the MDS controller. An oscilliscope is r ...

12121us ID pin 11 8us 2D pin 11 128us IE pin 11 2ms 2E pin 11 32ms IG pin 11 32121ms IF pin 11 5sec Square (this counter counts bits during reads, period = 16 bit cell times) Square (continuously running counter with period = one bit cell time) Usually square (continuously running counter with period = 16 bit cell times) Square (continuously running counter with period = 256 bit cell times) Square (counter with period = one sector time if sector ...

READ BIT· SHIFT 2A pin 15 SAVED READ DATA 9G pin 9 READ SHIFT REG SE pins 3,4,5,6 10,11,12,13 always high .Sus pulse every 8us .Suspulse every 7.Sus .Sus pulse every 8us always low 8us period square wave always low always high 6. This step checks-out the timing signals for reading and· writing. For this step the drive should have its power on and the ribbon cable should be connected between drive and controller. The following program ( ...