MA2909/11
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DS3577-3.4
PRELIMINARY INFORMATION
The MA2909/11 Microprogram Sequencer is fully
compatible with the industry standard 2909A and 2911A
components, and forms part of the GPS 2900 Series of
devices. The series offers a building block approach to
microcomputer and controller design, with each device in the
range being expandable to permit efficient emulation of any
microcode machine.
The devices have tristate outputs and have an internal
address register, with all internal registers changing state on
LOW to HIGH clock transition.
The 4-bit slice can cascade to any number of microwords.
Branch input for N-way branches is supported. Additional
features include:
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4-bit cascadable microprogram counter.
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4 x 4 file with stack counter supporting nesting
microsubroutines.
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Zero input for returning to the zero microcode word.
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Individual OR input for each bit for branching to higher
microinstructions (2909 only).
The 2909 is a 4-bit wide address controller intended for
sequencing through a series of microinstructions contained in
a ROM or PROM. Two 2909s may be interconnected to
generate an 8-bit address (256 words), and three may be used
to generate a 12-bit address (4K words).
The 2909 can select an address from any of four sources:
1) A set of external direct inputs (D);
2) External data from the R inputs, stored in an internal
register;
3) A four-word push/pop stack; or
4) A program counter register (which usually contains the
last address plus one).
The push/pop stack includes certain control lines so that it
can efficiently execute nested subroutine linkages. Each of the
four outputs can be OR’ed with an external input for conditional
skip or branch instructions, and a separate line forces the
outputs to all zeroes. The outputs are three-state.
The 2911 is an identical circuit to the 2909 except the four
OR inputs are removed and the D and R inputs are tied
together.
FEATURES
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Fully Compatible with Industry Standard 2909A and
2911A Components
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Radiation Hard CMOS SOS Technology
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High SEU Immunity
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High Speed / Low Power
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Fully TTL Compatible
APRIL 1995
RADIATION HARD MICROPROGRAM SEQUENCER
MA2909/11
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