Peritek VCD-V, User Manual

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Peritek
Programming On-board Devices and Memories 5-15
User's Guide is a necessary adjunct to a comprehensive understanding of
this device and can be ordered from TI or Peritek (see Section 1.2). Peritek
offers in-depth software support, which is covered in Chapter 3.
Note that the 34020 registers can be accessed as long words in D32 mode
by the VMEbus (when the LAR=0), consistent with the register
organization shown in the 34020 User's Guide. When accessing 34020
registers as 16-bit words, the order of the registers is
reversed from what
is shown in the 34020 manual.
34020 side VME word
address address
0 2
2 0
4 6
6 4
etc. etc
5.3.1 34082 Floating Point Coprocessor
The 34082 Floating Point Unit (FPU) chip can be installed in the socket
provided on the board. When properly utilized, it can significantly enhance
performance. TI compiler/assembler switches must be set to use it. Since
the chip select for the FPU always responds, you must run an FPU
instruction. An uncompleted operation will reveal its absence. The
Coprocessor ID# for the 34082 is
0 .
The 34082 conforms to the IEEE floating point standard P754 R10.0 for
high level math functions. In addition, it offers transcendental functions
(trigonometrics, hyperbolics, exponentials, logarithmics, etc.) and non-
transcendental functions (absolute values, square roots, negate, etc.)
performed to 32-bit, 64-bit, or 80 bit precision.
Typical instructions sequences also include copying data between the
34020 and the FPU, accessing memory, and executing internal instuction
microcode. See Section 1.1 for a complete description of the functions of
the FPU.
5.3.2 Writemask Register
The 34020 writemask register is a 32-bit read/write register located in the
TI register buffer (LAR = 0). It is used to enable any or all of the bit planes
in graphics memory (VRAM). This memory has a write-per-bit feature
which allows bit planes to be selectively write enabled. The
complement