HP 3562A, Руководство по обслуживанию

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MOD E L 3562A C I RCU IT D E SCRI PT I O N S
4 . The global RAM assemb ly places the data o n the global data b u s and activates the
G lobal Data Strobe signal (G DSL) which latches the data into the global bus registers.
5 . The global RAM assembly sets the MGFPPL l ine low to i nform control PA L 1 th at the
first half of the 32 bit data word has been loaded into the FPP assem bly.
6. Control PAL 1 sets global add ress l i ne 1 (GA1 L) high which increments the address
to global RAM by one for the second half of the data word.
7. The second half of the data word is now loaded into the global bus registers.
Arithmetic Logic Units (ALUsJ
The Arithmetic Logic U n its (ALUs) su bblock consists of six 4-bit sl iced arithmetic-oriented
m icroprocessors (AM2903) cascaded for up to 24-b it mathematic operations. The ALUs
can do com plete arithmetic and logic instructions i nclud i ng mu ltipl ication, d ivision, and
normal ization. Arithmetic and logic instru ctions are read from the ALUs instru ction bus
by the ALUs i nternal instruction decoder.
The ALUs have a 1 6 x 24 bit RAM for storing data. To load the ALUs RAM, the data i n
the global b u s registers i s placed o n the Y bus when MAN L i s active and on the B bus
when EXPL is active. The A Port Add ress from the m icrocode memory determines the
storage location of the data block add ress (u pper Y bus) and the B Port Address deter­
m ines the location of the B bus data and the location of the data com ing in and going
out on the Y bus.
The ALUs perform operations using two operands. Mu ltiplexors i n the ALUs provide
selection of various pairs for the operands which can be data from the ALUs RAM or data
from the external buses.
After the ALUs have completed an operation, several status bits are sent to the cond ition
code mu ltiplexor for testing. The status bits are as fol lows:
7 1: D (\
L- L .,,'-'
I nd icates the ALUs Y bus output is zero (al l 24 bits)
a negative resu lt.
OVR
From the most sign ificant ALU (U31 0) ind icating an operation has resulted in an
overflow.
CN + 4
From the most sign ificant ALU (U31 0) ind icating a carry-out of the ALU.
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