ocr: 512K mod. for Macintosh with rev. C motherboard Cut trace between pins 1 and 2 on 47 Ohm solder side 16 Voc YA 7 +5ul0L L 14 YB 9 N.C. Ram A9 O sO 2 3 S1 A18 0 - 4 SO o 74F253 S1 05 A17 o6 6 INOA INOB 10 Gnd 07 4 5 IN1A IN2A IN1B IN2B 11 12 3 IN3A IN3B 13 Seven Teedthrougns OEA OEB 15 near location E3 on GND rev. C motnerboard. 8 T.Slaight 8/31/85 rev. 1 instructions: 1) Remove 16 64k RAM chips and replace them with 200ns ori taster 256k RAM chips. 2) Add 74F253 multipleser chip and 47 ohm resistor as shown above.
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