80C286 datasheet(49/65 Pages) RENESAS

49 / 65 page

80C286

FN2947 Rev.3.00

Page 49 of 65

January 28, 2008

ASSUMING WORD-ALIGNED MEMORY OPERAND. IF ODD ALIGNED, 80C286 TRANSFERS TO/FROM MEMORY BYTE-AT-A-TIME WITH TWO MEMORY

CYCLES.

FIGURE 38. 80C286 PEREQ/PEACK TIMING FOR ONE TRANSFER ONLY

NOTES:

54. PEACK always goes active during the first bus operation of a processor extension data operand transfer sequence. The first bus opera-

tion will be either a memory read at operand address or I/O read at port address 00FA(H).

55. To prevent a second processor extension data operand transfer, the worst case maximum time (Shown above) is

3 x

- 12AMAX -

MIN. The actual configuration dependent, maximum time is: 3 x

- 12AMAX -

MIN + N x 2 x

. N is the

number of extra TC states added to either the first or second bus operation of the processor extension data operand transfer sequence.

FIGURE 39. INITIAL 80C286 PIN STATE DURING RESET

NOTES:

56. Setup time for RESET

 may be violated with the consideration that 1 of the processor clock may begin one system CLK period later.

57. Setup and hold times for RESET

 must be met for proper operation, but RESET  may occur during 1 or 2.

58. The data bus is only guaranteed to be in a high impedance state at the time shown.

Waveforms (Continued)

12A

12B

2

BUS

CYCLE TYPE

VCH

CLK

VCL

1

 S0

A23 - A0

M/IO,

PEACK

PEREQ

2

1

2

1

2

1

I/O READ IF PROC. EXT. TO MEMORY

MEMORY READ IF MEMORY TO PROC. EXT.

MEMORY WRITE IF PROC. EXT. TO MEMORY

I/O WRITE IF MEMORY TO PROC. EXT.

MEMORY ADDRESS IF PROC. EXT. TO MEMORY TRANSFER I/O PORT

ADDRESS 00FA(H) IF MEMORY TO PROC. EXT. TRANSFER

I/O PORT ADDRESS 00FA(H) IF PROC. EXT. TO MEMORY TRANSFER

MEMORY ADDRESS IF MEMORY TO PROC. EXT. TRANSFER

(SEE NOTE 54)

(SEE NOTE 55)

COD INTA

12B

2

BUS

CYCLE TYPE

VCH

CLK

VCL

1

RESET

A23 - A0

(SEE NOTE 56)

2

1

2

1

2

1

2

UNKNOWN

 S0

BHE

M/IO

COD/INTA

LOCK

DATA

HLDA

PEACK

AT LEAST

(SEE NOTE 57)

(SEE NOTE 58)

16 CLK PERIODS

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