Heading:qjk40(635) MOS LSI Testersy756qjk40 Page Numbers: Yes X: 527 Y: 10.5"qjk40 Inter-Office Memorandumz18592l4445y762\f5b To SSL-LSI Date August 30, 1979z18592l4445d2998e21(0,65535)(1,4445)(5,11684)(6,14146)\f1 2f0t2 1t0 7t6 1f1t0 4f0t7 1t0 From Jerry Roylance Location Palo Altoz18592l4445d2998y716e25\f1 4f0t2 1t0 14t6 1f1t0 8f0t7 1t0 Subject MOS LSI Testers Organization PARCz18592l4445d2998e25\f1 7f0t2 1t0 15t6 1f1t0 12f0t7 1t0 XEROX z18592l508y644e14(2116)\f2 5f0 Filed on: [ivy]ATester.memoe30 e10 Tester Description. The MOS tester is simply a hardware bit flipper. Sixty-four pin drivers send data to the test sockets and read the data coming back. The input and output data appear like memory locations to the Alto; consequently, the Alto can read or set 16 pins (1 word's worth) at a time. The tester's pin driving circuit has a high impedance, a property that obviates the need for tristateing the pin drivers: if the device pin undertest is output, it will have no trouble overcoming the drivers output impedance. On the otherhand, if the device pin is an input (which has a much higher impedance), then the pin will follow the driver. The high impedance output also has the feature that +5 or GND can be connected to the driver without damage. Thus the user can connect up the chip power without disconnecting the pin drivers.e12jk40\b19B The tester is an IO device that looks like 8 memory locations. The user has to write the programs that model his chip and set these locations to the proper values.e12jk40 How to Use it. After writing your programs, set up the hardware. The Alto Universal Board (AUB) (the one with all the TTL on it) must be plugged into the Alto II. When the logic bay is pulled out, the slots for the different cards are visible on the right side. The AUB must be plugged into slot 5, 6, or 7 (the slots are numbered on the machine; 1 is at the top), component side up. The AUB unfortunately has notches cut in the edge connector and, as luck would have it, we need to use the missing pin. On the backplane, connect a jumper from pin 02 to pin 58 for the slot you are using. The backplane slots are labelled J5, J6, and J7 for slots 5, 6 , and 7.e12jk40\b14B496b84B Connect the cables from the AUB to the test jig. If you are only using the 40 pin socket, only one cable is needed; it plugs into the header next to the 40 pin socket.e12jk40 Software. fooe12jk40\b9B Inheiritance from the D0 tester.e12jk40 Advantages. The test jig accepts 40 pin DIPs and 64 pin QUIPs; the only wiring the user needs to do is running power and ground to the appropriate pins. The tester can send out bits moderately fast if they have been precomputed. pIf speed is really needed, the interface can be microcoded. Microcode freaks can tie pin 3 of IC #aa49 low to let the microcode read and write 16 pins in the same memory cycle.e12jk40\b11B Disadvantages. User interface.e12jk40\b14B Testing TTL. This tester was designed to test MOS circuits. TTL circuits do not have the high impedance that MOS circuits have, and so the tester cannot handle them without some modifications. To test an LS TTL part, change the following parts of the pin drivers: replace the 8 LS374s with S74. The Schottky 74 can supply 6.5mA opposed to the LS 2.6mA. Replace the 8 DIP packages of 2.4K resistors coming from the S74s with 680 ohm resistors. The voltage drop across these resistors will be 280 millivolts for a standard LS load; the voltage drop is excessive for other families, so they cannot be tested with the resistors in place. Removing the resistors (ie, setting them to zero for the TTL package's inputs) means tristate circuits cannot be tested and the resistors must be configured for every new part.e12jk40\b12B Relation to other testers. There are a few other testers that preceded this tester. Bob Baldwin designed a tester last summer, but which had unfortunately been mislaid for most of this summer. His design connects to an Alto via the Diablo port and the X register. [Bob describes this design on [ivy]Tester.bravo.] Near the beginning of the summer he considered reworking the tester, but his thesis was more pressing. At that time we considered some alternatives to that design, and it was then that the idea of using open collector drivers came up (Rob Mathews later improved upon that).e12jk40\b26B Rob Mathews wanted a tester for his class a Stanford, so he started designing one in CMOS. While his design has the feature of being compatable with any computer that has an RS-232C interface, that same interface also limits the testing speed to 1 pin per millisecond. While this would be adequate for static designs and dynamic designs that have few inputs, it would not serve for larger dynamic designs.e12jk40 I went ahead and designed a tester such as Bob and I had talked about. It connected through the Alto's Diablo port. When tracking down an Alto Univeral Board to build the tester on, I talked with Ted Strollo. He was then deeply involved with making his AltoTitanic film processing interface; he suggested I steal his interface, thus going directly into the Alto's memory bus instead of through the Diablo port. I debated that question, and finally agreed; my reasons were confused and questionable, though. Ted's design had not been debugged yet, so I let him trip a few times before gobbling down his interface. The documentation on Alto interfacing is very scanty and somewhat confusing because signal names change; Ted based his design on a typewritten document by N. Tobol, ALTO II Memory Bus Interface, September 13, 1976 and AL2TBLT, a tablet interface. Another document is AltoInterface.press, April 1973.e12jk40\785i28I Alto Universal Interface Board. This board contains the pin driving circuits and the interface to the Alto. Construction just involves getting the board stitchwelded and stuffed. There are 17 dip platforms that need to be made; 16 of them are just full of resistors; the 17th has a bypass capacitor and a pullup resistor.e12jk40\b31B Test Jig Printed Circuit Board. Five test jig printed circuit boards were made by Cybernex. These boards need the following modifications:e12jk40\b31B The power supply holes have to be drilled out. Five pins need to be drilled to 0.045; the 2 mounting holes need to be enlarged to clear a 4-40 screw. The ground connection to the power supply is wrong; cut the trace and make a jumper to the center pin. Mounting holes for the chassis box. Chassis and the printed circuit board have no mounting holes; drill them to suit, but avoid shorting the AC line to the chassis. Wirewrap pin holes for ground. Drill some holes for two ground wirewrap pins. The copper boarder of the board is ground.l4269e12jk40 Where to find it. The sil files and wirelists are in [ivy]ATester-Rev-C.dm.e12jk40\b17B e12jk40 Word, Cable, and Pin Assignments.e12jk40\b32B The test jig has two sockets on it, a 40 pin and a 64 pin. Each of these pins corresponds to a bit position in two words of the Alto's memory. One of these words is used to write a group of 16 pins, the other to read the group.e12jk40 Alto Location Bit Position (0 is MSB) Write Read 177300 177304 7 6 5 4 3 2 1 0 15 14 13 12 11 10 9 8 Card Edge 01 02 03 04 05 06 07 08 11 12 13 14 15 16 17 18 Cable #1 01 03 05 07 09 11 13 15 21 23 25 27 29 31 33 35 Cable #2 40 Pin Socket 40 39 38 37 36 35 34 33 32 31 30 29 28 27 26 25 64 Pin Socket 34 36 38 40 42 44 46 48 50 52 54 56 58 60 62 64 177301 177305 7 6 5 4 3 2 1 0 15 14 13 12 11 10 9 8 Card Edge 62 63 64 65 66 67 68 69 72 73 74 75 76 77 78 79 Cable #1 02 04 06 08 10 12 14 16 22 24 26 28 30 32 34 36 Cable #2 40 Pin Socket 01 02 03 04 05 06 07 08 09 10 11 12 13 14 15 16 64 Pin Socket 33 35 37 39 41 43 45 47 49 51 53 55 57 59 61 63 177302 177306 7 6 5 4 3 2 1 0 15 14 13 12 11 10 9 8 Card Edge 37 38 39 40 41 42 43 44 47 48 49 50 51 52 53 54 21 22 23 24 82 83 84 85 Cable #1 41 43 45 47 42 44 46 48 Cable #2 01 03 05 07 09 11 13 15 21 23 25 27 29 31 33 35 40 Pin Socket 24 23 22 21 17 18 19 20 64 Pin Socket 02 04 06 08 10 12 14 16 18 20 22 24 26 28 30 32 177303 177307 7 6 5 4 3 2 1 0 15 14 13 12 11 10 9 8 Card Edge 98 99 100 101 102 103 104 105 108 109 110 111 112 113 114 115 Cable #1 Cable #2 02 04 06 08 10 12 14 16 22 24 26 28 30 32 34 36 40 Pin Socket 64 Pin Socket 01 03 05 07 09 11 13 15 17 19 21 23 25 27 29 31 e12jk40(635)