software compatible with i387 based on CX83D87 with power saving technology pin compatible with i80287 (DIP) pin compatible with i80287XLT (PLCC) alternative designation Cyrix 287XL (+) (?)
FasMath CX-83S87
i386SX
1990
16 MHz 20 MHz 25 MHz 33 MHz
PLCC-68
1.0 µm CMOS
alternative designation Cyrix 387SX pin and software compatible with i387SX
FasMath CX-83D87
i386DX
1989
16 MHz 20 MHz 25 MHz 33 MHz 40 MHz
PGA-68, PQFP-80 to PGA-68
1.0 µm CMOS
integrated power management code name of the design: Little Seven (L7) pin and software compatible with i387DX alternative designation Cyrix 387DX (+)
Cyrix 387SL
i386SL
25 MHz
PLCC-68
CMOS
pin and software compatible with i387SL (?)
Cx487DLC
i386DX Cx486DLC
1992
33 MHz 40 MHz
PGA-68
0.8 µm CMOS
for Cx486DLC compatible in the i386 socket
Cx487S
Cx486S Cx486DX
i486SX i486DX
1993
33 MHz 40 MHz
PQFP-80
0.8 µm CMOS
Cx87DLC
i386DX Cx486DLC
33 MHz 40 MHz
PQFP-80 to PGA-68
CMOS
for Cx486DLC compatible in the i386 socket
Cx87SLC
i386SX Cx486SLC
25 MHz 33 MHz
PLCC-68 PQFP-80
CMOS
alternative designation CXSLC87
FasMath CX-EMC87 (AutoMath)
i386
16 MHz 20 MHz 25 MHz 33 MHz 40 MHz
PGA-121
1.0 µm CMOS
software compatible like CX-83D87 with Weitek mode (memory mapping etc.) is supported by AutoCAD pin compatible with Weitek WTL3167 (?)
approx. 120,000 transistors Die size: 7 mm × 7.5 mm Compatible with the i386DX The sources are not entirely clear, but are probably not compatible with the 80386SX
i387DX
i386DX
1989
16 MHz 20 MHz 25 MHz 33 MHz
PGA-68
1.0 µm CHMOS IV
Improved i387 Die size: 5.5mm × 5.5mm Compatible with the i386DX only
i387SX
i386SX
16 MHz 20 MHz 25 MHz 33 MHz
PLCC-68
1.0 µm CHMOS IV
For the i386SX only
i387SL
i386SL
1992
16 to 25 MHz
PLCC-68
1.0 µm CHMOS IV
integrated power management for mobile applications
i487SX
i486SX
1991
20 MHz 25 MHz 33 MHz
PGA-169
1.0 µm CHMOS IV
full-fledged i486DX one pin deactivates the existing i486SX
NexGen
designation
suitable for ...
Year of introduction
Clock frequencies
casing
technology
description
Nx587
Nx586
never officially appeared
60 MHz (?) 66 MHz (?) 90 MHz (?)
PGA-143
0.5 µm CMOS
700,000 transistors with an operating voltage of 4.0 V VLB mainboards with Nx587 sockets only appeared as prototypes
as samples
ULSI
designation
suitable for ...
Year of introduction
Clock frequencies
casing
technology
description
US83C87
i386DX
1991
20 MHz 25 MHz 33 MHz 40 MHz
PGA-68 PLCC-68
1.2 µm CMOS
FPU clock always the same CPU clock compatible with i387 a little faster than the i387DX, especially in the basic arithmetic operations transcendental functions only slightly faster
Math-Co DX
i386DX
33 MHz 40 MHz
PGA-68
CMOS
like ULSI US83C87
Math-Co DX-2 (US83D87-C)
i386DX
33 MHz (internal 66 MHz)
PGA-68
CMOS
like ULSI US83C87, but with asynchronous clock internal clock doubling
Math-Co DX / DLC
i386DX Cx486DLC
40 MHz
PGA-68
CMOS
MathCo DX / DLC2-50 (US83D87-C)
i386DX Cx486DLC
25 MHz (internal 50 MHz)
PGA-68
CMOS
internal clock doubling with asynchronous clock
Math-Co SX (US83S87)
i386SX
16 MHz 20 MHz 25 MHz 33 MHz
PLCC-68
CMOS
like ULSI US83C87 with power saving and sleep mode
Math-Co SX / SLC
i386SX Cx486SLC
33 MHz 40 MHz
PLCC-68
CMOS
Weitek abacus
designation
suitable for ...
Year of introduction
Clock frequencies
casing
technology
description
WTL1167
i386DX
before i387 (?)
20 MHz
Small PGA (?) - 121 board with three ICs
WTL1164: 2.5 µm NMOS WTL1165: 2.5 µm NMOS
neither pin nor software compatible with i80x87 only software support for square root small circuit board with Weitek WTL1163, WTL1164 and WTL1165
WTL3167
i386DX
1989 (?)
20 MHz 25 MHz 33 MHz
PGA-121
CMOS
neither pin nor software compatible with i80x87 a W3167 socket is required
WTL4167
i486 i487SX
25 MHz 33 MHz
PGA-142
CMOS
neither pin nor software compatible with i80x87 a W4167 socket is required