PD6710 Datasheet, PDF (86/138 Pages) Intel Corporation – ISA-to-PC-Card (PCMCIA) Controllers

PD6710/’22 — ISA-to-PC-Card (PCMCIA) Controllers
11.3
Bits 5:0 — Command Multiplier Value
This field indicates an integer value N_val from 0 to 63; it is combined with a prescalar value (bits
7:6) to control the length that a command is active.
Bits 7:6 — Command Prescalar Select
00 Npres = 1
01 Npres = 16
10 Npres = 256
11 Npres = 8192
This field chooses one of four prescalar values N_pres that are combined with the value of the
Command Multiplier Value (bits 5:0) to control the length that a command is active.
Recovery Timing 0–1
Register Name: Recovery Timing 0–1
Index: 3Ch, 3Fh
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Register Per: socket
Register Compatibility Type: 365
Bit 1
Bit 0
Recovery Prescalar Select
Recovery Multiplier Value
RW:00
RW:000011
There are two separate Recover Timing registers, each with identical fields. These registers are
located at the following indexes:
Index Recovery Timing
3Ch Recovery Timing 0
3Fh Recovery Timing 1
The Recovery Timing register for each timing set controls how long a PC Card cycle’s command
(that is, -OE, -WE, -IORD, -IOWR; see Table 2 on page 20) recovery will be, in terms of the
number of internal clock cycles.
The overall command recovery timing length R is programmed by selecting a 2-bit prescaling
value (bits 7:6 of this register) representing weights of 1, 16, 256, or 8192, and then selecting a
multiplier value (bits 5:0) to which that prescalar is multiplied to produce the overall command
recovery timing length according to the following formula:
R = (N_pres × N_val) + 1
The value of R, representing the number of internal clock cycles for command recovery, is then
multiplied by the internal clock’s period to determine the command recovery time (see “PC Card
Bus Timing Calculations” on page 109 for further discussion).
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Datasheet