ii
4.1.2 Nonmaskable Interrupt Logic......................................................................................................... 55
4.1.3 Drive Select Latch and Motor On Logic......................................................................................... 55
4.1.4 Wait State Generation and WAITIMOUT Logic............................................................................. 56
4.1.5 Clock Generation Logic ................................................................................................................. 56
4.1.6 Disk Bus Selector Logic................................................................................................................. 56
4.1.7 Read/Write Data Pulse Shaping Logic .......................................................................................... 56
4.1.8 Disk Bus Output Drivers ................................................................................................................ 56
4.1.9 Write Precompensation and Clock Recovery Logic ...................................................................... 56
4.1.10 Floppy Disk Controller Chip ........................................................................................................... 57
4.1.11 Adjustments and Jumper Options.................................................................................................. 57
FDC Board to CPU Board Signal Description ............................................................................... 58
SCHEMATIC 8000095, PCB CONTROLLER #8858060 .............................................................. 59
Parts List, FDC PCB #8858060..................................................................................................... 61
4.2 Model 4 FDC PCB #8858160 ........................................................................................................ 63
4.2.1 Control and Data Buffering ............................................................................................................ 63
4.2.2 Nonmaskable Interrupt Logic......................................................................................................... 63
4.2.3 Drive Select Latch and Motor ON Logic ........................................................................................ 63
4.2.4 Wait State Generation and WAITIMOUT Logic............................................................................. 63
4.2.5 Clock Generation Logic ................................................................................................................. 64
4.2.6 Disk Bus Selector Logic................................................................................................................. 64
4.2.7 Disk Bus Output Drivers ................................................................................................................ 64
4.2.8 Write Precompensation and Write Data Pulse Shaping Logic ...................................................... 64
4.2.9 Clock and Read Data Recovery Logic........................................................................................... 66
4.2.10 Floppy Disk Controller Chip ........................................................................................................... 66
Schematic 8000268, FDC PCB #8858160 .................................................................................... 67
Component Layout, FDC PCB #8858160...................................................................................... 69
Parts List, FDC PCB #8858160..................................................................................................... 71
SECTION V Mini-Disk Drive (not available).................................................................................................... 73
SECTION VI Power Supplies (not available)................................................................................................... 75
SECTION VII Video Monitor (not available)...................................................................................................... 77
SECTION VIII Exploded View / Parts List.......................................................................................................... 79
Exploded View, Model 4 Computer, Catalog #26-1067/8/9........................................................... 81
Parts List, Model 4 Computer, #26-1067/8/9................................................................................. 83
SECTION IX RS232C Circuit Board.................................................................................................................. 85
9.1 RS-232C Technical Description..................................................................................................... 87
9.2 Pinout Listing ................................................................................................................................. 88
9.3 Port and Bit Assignments .............................................................................................................. 89
RS-232 Board to CPU Board Signal Description........................................................................... 91
Schematic #8000076, RS232C Printed Circuit Board................................................................... 93
Parts List, RS232C PC Board........................................................................................................ 95
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