Compaq EV68A specifications Design Examples, Amask, Implver

Design Examples

2.15.1 AMASK

The 21264/EV68A returns the AMASK instruction values provided in Table 2–15.The I_CTL register reports the 21264/EV68A pass level (see I_CTL[CHIP_ID], Section 5.2.15).

Table 2–15 21264/EV68A AMASK Values

21264/EV68A Pass Level	AMASK Feature Mask Value
See I_CTL[CHIP_ID], Table 5–11	1307 16

The AMASK bit definitions provided in Table 2–15are defined in Table 2–16.

Table 2–16 AMASK Bit Assignments

Bit Meaning

0Support for the byte/word extension (BWX)

The instructions that comprise the BWX extension are LDBU, LDWU, SEXTB, SEXTW, STB, and STW.

1Support for the square-root and floating-point convert extension (FIX)

The instructions that comprise the FIX extension are FTOIS, FTOIT, ITOFF, ITOFS, ITOFT, SQRTF, SQRTG, SQRTS, and SQRTT.

2Support for the count extension (CIX)

The instructions that comprise the CIX extension are CTLZ, CTPOP, and CTTZ.

8Support for the multimedia extension (MVI)

The instructions that comprise the MVI extension are MAXSB8, MAXSW4, MAXUB8, MAXUW4, MINSB8, MINSW4, MINUB8, MINUW4, PERR, PKLB, PKWB, UNPKBL, and UNPKBW.

9Support for precise arithmetic trap reporting in hardware. The trap PC is the same as the instruction PC after the trapping instruction is executed.

12Support for using a prefetch with modify intent to improve the performance of the first attempt to acquire a lock. When clear, indicates possible prefetch error with locks, described in waiver 10 to the Alpha Architecture and in the prefetch section of the appropriate processor (21264/EV6 and 21264/EV67) documents.

2.15.2IMPLVER

For the 21264/EV68A, the IMPLVER instruction returns the value 2.

2.16 Design Examples

The 21264/EV68A can be designed into many different uniprocessor and multiproces- sor system configurations. Figures 2–12and 2–13illustrate two possible configura- tions. These configurations employ additional system/memory controller chipsets.

Figure 2–12shows a typical uniprocessor system with a second-level cache. This sys- tem configuration could be used in standalone or networked workstations.

2–38Internal Architecture 21264/EV68A Hardware Reference Manual