Cyrix and IBM 6x86MX 6x86L 6x86KV and
MII Chip ID guide
Finding information on these chips is very difficult. Cyrix
has been bought by VIA and datasheets are no longer available. Cyrix, IBM,
ST and National all made the Cyrix line of CPUs. Each had their own marking
system and ID codes for their chips. This makes Identifying them quite hard.
Not to mention a single performence rating having 3 or 4 speeds and made on
3 different silicon processes. Thank goodness there werent many different
packages. Cyrix 6x86 CPUs spanned 220MHz but their PR values spanned 343 (90-433).
IBM
Cyrix
PR Values Table
Raw Data Used in this Guide
Cyrix Time Line
IBM
IBM CPUs have the ID markings on top. They are a bit cryptic
but once you look at them they really do make sense. Please note that a IBM
6x86MX is the same CPU as a Cyrix 6x86MX or a Cyrix M2. IBM chose not to change
the name of the CPU while Cyrix did to better compare it to the Pentium II
and K6-II.
IBM26x86MX-mVcPRxxxpr
xxx = Performance Rating
m = Multiplier
A = 2.0
B = 2.5
C = 3.0
D = 3.5
p = package
G = 296 pin Gold plate
H = 296 pin Black Top
P = PPGA
c = core voltage
A = 2.9V
B = 3.0V
C = 3.1V
r = mask revision
A =A-step
B = B-step
C = C-step
D = D-step
E = E-step
F = F-step
IBM26 6x86L-mVcPxxxpr
xxx = Performance Rating
m = Multiplier
2 = 2.0
3 = 3.0
c = Core Voltage
A = 2.8Volts
p = Package
G = 296 pin CPGA
r = Revision
A = 2.4 (G8 Process)
B = 2.5 (G8 Process)
C = 2.7 (G8 Process)
D = 3.6 (G9 Process)
E = 3.7 (G9 Process)
IBM26 6x86-mVcPxxxpr
xxx = Performance Rating
m = Multiplier
2 = 2.0
3 = 3.0
c = Core Voltage
2 = 3.3 Volts
7 = 3.52Volts
p = Package
G = 296 pin CPGA
r = Revision
A = 2.4 (G8 Process)
B = 2.5 (G8 Process)
C = 2.7 (G8 Process)
D = 3.6 (G9 Process)
E = 3.7 (G9 Process)
Cyrix
Cyrix CPUs are even harder to identify. They follow the same PR scheme as
IBM but the codes are harder to understand. the ID code for a Cyrix is located
on the BOTTOM of the chip on all but the black top CPUs and Mobiles. Cyrix
CPUs were produced on .35, .30, .25 and .18 micron processes. Quite often
a single PR will be made in no less then 3 process technologies and 2 speeds
with 2 bus speeds. All 6x86MX and M2 CPUs are 2.9 Volt. The exception to this
is that all .18 micron M2s are 2.2 Volts.
6x86
6x86L
6x86MX
Liscensed MII
PR Values
If you know of any more Cyrix ID info etc. Please e-mail me and I will add
it