Sharp MZ-5500 - Page 111

17. 8087 Coprocessor option
The 8087 nurnerica~ da ta processor handles arithrnetical operation of numeric
data of various types and it has the capability to handle transcendental
functions.
°Almost all signal lines are connected parallel with the 8086 CPU in view of
the hardware. It does not require any special interface . önd has capacity to
expand the CPU registers.
In view of software, the processing capacity of the CPU is largely increased
as if the CPU commands are expanded.
°The 8087 NDP has eight 80-bit registers as
shown in Fig.l and its configuration is as
shown in Fig.2. Almost all commands of the
8087 (data tran~fer, arithmetic operation,
comparison) are executed with the register
ST (0) or between ST (0) and other register
ST (0 - 7) or the memory.
°
Th er e are se ven kinds of data formats that
ca n be handl ed (Fig.3), but they are 79
S T
(0)
S T
(1)
S
T (2)
S
T
(3)
S
T
(4)
S
T
(5)
S
T
(6)
S
T
(7)
o
co nv e rt ed into the format when fetched
Fig.l 8087 registers
insid e th e 8087 be fore being stored (Fig.2).
I fuXPONENT' SIGNIFICAND '( .1 I
79 64 63 0
Fig.2 8087 register structure
Bina~y integer
WORD INTEGER
~I
15 0
SHORT INTEGER
~I
31 o
LONG INTEGER
~I
63
o
Decimal integer PACKED DECIMAL
Real number SHORT REAL
~IExp I Mantissa
31 23 o
LONG REAL
~IExp
Mantissa
63 52.
o
TEMPORARY REAL
~IExp
111 Mantissa
79 ·
o
Fig.3 8087 data forma~
\0<6
79 0