2/Theory of Operation
2-20
Internal Oscillator Control Functional Block
The Vector Output I/O Module contains a 1, 5, 10, and 20MHz internal
clock source that is available for vector driving. The desired clock can
be selected by writing to Drive Register 2 (U25) of the Main PCA
($DOX21) and specifying bits 1 and 0.
The Internal Oscillator Control Functional Block consists of a 20 MHz
Oscillator (U20), a 70HCT390 Dual Decade Ripple Counter (U21), a 74HC74
D-Type Flip-Flop (U28), and a 74AC151 8-Input Multiplexer (U22), all
located on the Main PCA.
Writing to U25 ($DOX21) using bit 1 and bit 0 selects the frequency of
the internal clock. Outputs BMUX1 and BMUX0 from U25 to U22 control the
selection of one of four clocks (see Table 2-7). These clocks are 20 MHz
(obtained directly from the 20 MHz Oscillator U20), 10 MHz (obtained
from U21 by dividing the 20 MHz clock by two), 5 MHz (obtained by
dividing the 10 MHz clock by two using U28), and 1 MHz (obtained by
dividing the 10 MHz clock by ten using U21). The Y output of U22 pin 5
goes directly to the Top PCA and is used by the SSLOGIC Functional Block
as one vector driving clock source. The Y- output from U22 pin 6 is
inverted by U19. This inversion gives OSC-CLK the same phase as the
INT-OSC output and delays it slightly to reduce the clock to vector-out
skew before being routed to the P1 pin 5 INT OSC output.
Table 2-7. U25 Drive Register 2 Bit Description (Write @ $D0X21)
___________________________________________________________________________
BIT SIGNAL 1 0
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7,6,5,4 ---- ---- ----
3 LCHI-/LCLO- LCHI- LCLO-
2 LTCCLR- NO LTCCLR- LTCCLR-
1 BMUX1*
0 BMUX0*
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*BMUX1 *BMUX0 FREQUENCY
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0 0 10 MHz
0 1 20 MHz
1 0 5 MHz
1 1 1 MHz
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Output Control Functional Block
The U10 PAL provides the majority of the output section control. It
provides the latching signals COMMAND0- and COMMAND1- to U5 and U6. It
provides the RAM-PORT- signal that controls the chip counter U9 and the
RAM Select U11 PAL. It decodes writes to $D0X51 to generate RAM-STROBE,
which provides the soft-clocking ability for vector output. It supplies
Summary of Contents for 9100 Series
Page 6: ... iv ...
Page 8: ... vi ...
Page 15: ...2 Theory of Operation 2 3 Figure 2 1 Input Section Functional Block Diagram ...
Page 16: ...2 Theory of Operation 2 4 Figure 2 2 Output Section Functional Block Diagram ...
Page 19: ...2 Theory of Operation 2 7 Figure 2 3 Input Section Address Decoding Summary ...
Page 42: ...2 Theory of Operation 2 30 ...
Page 50: ...4 List of Replaceable Parts 4 2 ...
Page 54: ...4 List of Replaceable Parts 4 6 Figure 4 1 9100A 017 Final Assembly ...
Page 55: ...4 List of Replaceable Parts 4 7 Figure 4 1 9100A 017 Final Assembly cont ...
Page 57: ...4 List of Replaceable Parts 4 9 Figure 4 2 A1 Main PCA ...
Page 59: ...4 List of Replaceable Parts 4 11 Figure 4 3 A2 Top PCA ...
Page 64: ...4 List of Replaceable Parts 4 16 ...
Page 66: ...5 Schematic Diagrams 5 2 ...
Page 67: ...5 Schematic Diagrams 5 3 Figure 5 1 A1 Main PCA ...
Page 68: ...5 Schematic Diagrams 5 4 Figure 5 1 A1 Main PCA cont ...
Page 69: ...5 Schematic Diagrams 5 5 Figure 5 2 A2 Top PCA ...
Page 70: ...5 Schematic Diagrams 5 6 Figure 5 2 A2 Top PCA cont ...
Page 74: ...Index Index 4 ...