Intel mcs-48 manual 8272

8272

PIN DESCRIPTION

	PIN		CONNECTION
		UO
NO.	SYMBOL		TO
1	RST	I	"p
2	1m	l'	"p

DESCRIPTION

Reset: Places FOe in idle state. Resets output lines to FOD to "0" (low)

Read: Control signal for transfer of data from FOC to Data Bus. when "0" (low)

	PIN		CONNECTION
		UO
NO.	SYMBOL		TO
40	VCC
39	RWISEEK	0	FOO
38	LCTIOIR	0	FOO

DESCRIPTION

D.C. POWER + 5V

Read Write/SEEK: When "1" (high) Seek mode selected and when "0" (low) ReadlWrite mode selected

Low Current/Direction: Lowers Write current on inner tracks In ReadlWrlte mode, deter· mines direction head will step

3	WR	l'	"p	Write: Control signal for
				transfer of data to FOe via Data
				Bus, when "0" (low)
4	CS	I	"p	Chip Select: Ie selected
				when "0" (low), allowing
				Ffi) and m to be enabled
5	Ao	I	"p	Data/Status Reg Select
				Selects Data Reg (AO = 1) or
				Stalus Reg (AO = 0)
				content
				be sent to Data Bus
6-13	OBo-OB7	I/O	"p	Data Bus: Bidirectional
				a-Sit Data Bus
14	ORO	0	OMA	Data DMA Request; DMA
				Request is being made by
				FOC when ORO "1"
15	OACK	I	OMA	DMA Acknowledge: DMA
				cycle Is active when "0"
				(low) 'andController Is
				performing DMA transfer
16	TC	I	OMA	Terminal Count: Indicates
				the termination of a DMA
				transfer when "1" (high)
17	lOX	I	FOO	Index: Indicates the beginning
				of a disk track
18	INT	0	"p	Interrupt: 'InterruptRequest
				Generated by FOC
19	CLK	I		Clock: Single Phase 8 MHz
				Squarewave Clock
20	GNO			Ground: D.C. Power Return

Note 1: Disabled when CS: 1.

37	FAlSTP	0	FOO
36	HOL	0	FOO
35	ROY	I	FOO
34	WPITS	I	FOO
33	FLTITRKO	I	FOO
31,32	PS"PSO	0	FOO
30	WR DATA	0	FOO
28,29	OS"OSO	0	FOO
27	HOSEL	0	FOO
26	MFM	0	PLL
25	WE	0	FOO
24	VCO	0	PLL
23	RO DATA	I	FOO
22	OW	I	PLL
21	WRCLK	I

in Seek mode

Fault Reset/Step: Resets fault

FFin FOD in ReadlWrite mode, provides step puises to move head to another cylinder in Seek mode

Head Load: Command which causes read/write head in FDD to contact diskette

Ready: Indicates FDD Is ready to send or receive data

Write ProtectlTwo-Slde: Senses Write Protect status In ReadIWrlte mode, and Two Side Media In Seek mode

Faultrrrack 0: Senses FDD fault condition In ReadlWrlte mode and Track 0 condition in Seek mode.

Precompensatlon (pre-shift): Write precompensation status during MFM mode. Deter· mines early, late, and normal times.

Write Data: Serial clock and data bits to FDD

Drive Select: Selects FOD unit

Head Select: Head 1 selected when "1" (high) Head 0 selected when "0" (low)

MFM Mode: MFM mode when "1", FM mode when "0"

Write Enable: Enables write data Into FOD

VCO Sync: Inhibits VCO in PLL when "0" (low), enables VCO when "1"

Read Data: Read data from FOD, containing clock and data bits

Data Window: Generated by PLL, and used to sample data from FDD

Write Clock: Write data rate to FDD FM = 500 kHz, MFM = 1 MHz, with a pulse width of

250 ns for both FM and MFM

9-53