MITSUBISHI ELECTRIC
5.25 INCH FLEXIBLE DISK DRIVES

MF501B	0.5 MB
MF503B	1.0 MB
MF504B	1.6 MB

SPECIFICATIONS and APPLICATION NOTES

The Mitsubishi MF500B range of double sided 5¼ inch flexible disk drives provide high performance and reliability giving a service life of over 20 000 hours.

•	Industry standard types offering 360KB, 800KB and 1.2MB formatted capacity.
•	New high compliance gimbal mounted head gives long media life and reliable data transfer
•	Excellent timing margin and radial alignment guarantees perfect data interchange between systems
•	MF504B (1.6MB) can read standard 360KB disks
•	MF503B (1.0MB) can be switched for 40 or 80 track operation
•	Dynamic clamping ensures perfect disk centreing
•	Industry standard interface and power connector
•	Latest VLSI technology combines bipolar amplifiers and CMOS logic in a single 80 pin ASIC

This booklet gives guidance for applying the range of 5'/4 inch floppy drives. For more details consult the standard specification manual for each model.

Performance specifications
		MF501B	MF503B	MF504B
Low density	MF504B
High Density	
MFM recording						
Unformatted capacity:-	Track	6.25KB	6.25KB	6.25KB	10.416KB	
	Disk	500KB	1000KB	1000KB	1666KB	
Formatted
capacity:-						
	Sector	0.256KB	0.256KB	0.256KB	0.512KB	
16 (15) sectors/
Track	Track	4.096KB	4.096KB	4.096KB	7.680KB	
	Disk	327.7KB	655.36KB	655.36KB	1228.8KB	
Transfer rate		250kb/S	250Kb/s	250/300Kb/s	500Kb/s	
Track density per inch	48 tpi	96 tpi	96 tpi	96 tpi	
Total tracks		80	160	160	160	
Access time						
Track to track	6 mS	3 mS	3 mS	3 mS	
Average	103 mS	94 mS	94 mS	94 mS	
Settling time	15 mS	15 mS	15 mS	15 mS	
Motor speed	300rpm	300rpm	300/360rpm	300rpm	
Motor start time	250 mS	400 mS	400 mS	500 mS	
Ready time	700 mS	700 mS	700 mS	700 mS	

Environmental conditions	Operating	Storage	Transportation	
Ambient temperature	5°C to 43 °C	-20°C to 60°C	-40°C to 60°C	
Relative humidity	20% to 80%	10% to 90%	5% to 95%	
Dimensions	Height 41mm	Width 146mm	Depth 195mm	
Weight	1.2Kg			

Reliability				
MTBF	10 000 POH or more	MTTR	30 minutes	
Unit life	5 years or 20 000 POH	Media life	3.5 million passes/track	
Error rate	Soft error	10-9 bit			
	Hard error	10-12 bit			
	Seek error	10-6 bit			

DC power connector	
Pin number	Voltage	
1	+12V DC	

4  3  2  1

PCB

2	0V	
3	0V	
4	+5 VDC	
DC power requirements	+ 5V ±5% 0.5A typ 0.7A
	+12V ±5% 0.6A typ 1.0A max

 A 0.25” frame ground connector is provided adjacent to the DC connector. The cut track option ‘FG’ isolates the DC OV from the frame ground.

Signal interface

	Signal	I/O	Pin	0V			
*	Spare	I/P	2	1	*	MF504B) This line switches between high and low density	
	In use	I/P	4	3			
	Drive select 3	I/P	6	5			
	Index	O/P	8	7	**	(MF501B) Standard ready or hold ready available	
	Drive select 0	I/P	10	9			
	Drive select 1	I/P	12	11			
	Drive select 2	I/P	14	13	**	(MF5038 & MF504B)
Standard ready, hold ready and disk-change available	
	Motor on	I/P	16	15			
	Direction select	I/P	18	17			
	Step	I/P	20	19			
	Write data	I/P	22	21	TTL levels	
	Write gate	I/P	24	23		
	Track 00	O/P	26	25	Low level (TRUE) OV to + 0.4V	
	Write protect	O/P	28	27	High level (FALSE) + 2.5V to + 5.25V	
	Read data	O/P	30	29	Input impedance 150 Ohms	
	Side one select	I/P	32	31	Receiver: SN7414N or equivalent	
**	Ready	O/P	34	33	Driver: SN7438N or equivalent	

Cabling and termination
Up to four drives may be connected by a ribbon cable in a daisy change configuration. A SIL terminator, supplied installed on the PCB, should be fitted to the last drive in the chain. On MF503B and MF5048 jumper ‘TD’ is installed to terminate drive select.
Power on sequence
No read/write operation may be performed until 100 mS after DC power is applied. The drive becomes ready after 600 mS (700mS for MF501B). The head must be stepped out to track 00 to provide a reference before track seeking begins.
Write precompensation
The drive uses high performance read/write heads with good compliance and media contact. This means that no write precompensation should be used. If write precompensation must be used, it should be 150 nS or less.
40 / 80 track switch option (MF503B)
The cut track option ‘ST’ may be cut to change to 40 track mode. A switch may be connected. An 80 track drive should not be used to write 40 track diskettes to be read by a 40 track drive. The PCB must not be damaged by track cuts or solder connections.

Option settings
Brackets around jumper name:– (MM) indicates jumper plug should be installed to select the function.
Jumper name	Function	
(DS0)	DRIVE SELECT 0 enables the drive.	
(DS1)	DRIVE SELECT 1 enables the drive. DS2 & DS3 etc.	
(MX)	Drive is selected regardless of DRIVE SELECT lines	
(MM) MS	Motor controlled by MOTOR ON signal	
MM (MS)	Motor controlled by DRIVE SELECT signal	
MM MS	Motor controlled by DRIVE SELECT AND MOTOR ON signal	
(MM) (MS)	Motor controlled by IN USE signal latched by DRIVE SELECT signal. Option IU must be jumpered. (MF501B motor controlled by MOTOR ON signal)	
(SR) DC HR DD	Standard READY sent on pin 34	
(SR) DC (HR) DD	HOLD READY sent on pin 34 (MF503B, MF504B)	
SR (DC) HR (DD)	DISK CHANGE (reset by DS) on pin 34 (MF5038, MF504B)	
SR (DC) HR DD	DISK CHANGE (reset by step) on pin 34	
SR DC	No ready signal sent	
     (RD)	Read data pulses inhibited by READY (MF504B)	
             (RI)	Index pulses gated by ready signal	
     (SS) SB	360 rpm when high density signal sent (MF504B)	
	300 rpm when low density signal sent (MF504B)	
      SS (SB)	360 rpm for high and low density (MF504)	
      (SS) SB (ND)	Low density 300 rpm set	
	LED lighting conditions (MF503B & MF504B)
MF501B LED is lit by IN USE OR DRIVE SELECT	
(lU) (IS) (IL)	If IN USE is set, DRIVE SELECT latches LED on	
(IU) ) IS (IL)	LED lit by sum of DRIVE SELECT above conditions	
(IU) IS IL	LED lit by logical sum of DRIVE SELECT and IN USE.	
(IV) (IS) IL	LED lit by IN USE signal	
IU IS IL	LED lit by DRIVE SELECT signal	
IU (IS) IL	LED will not light	
(IR)	May be used with all the above. Requires that drive is ready before LED will light. Standard or Hold Ready must be selected if (IR) is used.	
INPUT SIGNALS
Side one select
Logical ‘1’ selects head 0, logical ‘0’ selects head 1. A 100pS delay must be allowed after side select. After a write operation a 1mS delay (590pS for MF504B at high density) must be allowed before a side change or a track access. Direction select
Defines head stepping direction. Logical ‘1’ causes heads to step from the centre outward. Logical ‘0’ causes stepping inward.
Step
Pulses on this line move the head in the direction selected. The head steps one track on the trailing edge of a negative pulse (‘0’ to ‘1’).

Write gate
Logical ‘0’ enables data on the write line to be written on the selected side and track. Logical ‘1’ inhibits writing and enables reading. Data cannot be written if the write protect line is at ‘0’ because a write protected disk is present. Read data is output 1mS (590ps for MF504B at high density) after write gate becomes inactive.
Write data
Data written to the disk is sent on this line. The line is normally at ‘1’ and reverses the write current at the leading edge of a negative-going pulse (‘1’ to ‘0’). Writing is enabled by ‘0’ on the write gate.

Type	T1	T2	T3	T4	
360rpm HD	150 to 1100ns	2.0µs ± 10ns	4.0µs ± 20ns	3.0µs ±15ns	
360rpm LD	150 to 1800ns	3.33µs ± 17ns	6.7µs ± 33ns	5.0µs ±25ns	
300rpm	150 to 2100ns	4.0µs ± 20ns	8.0µs ± 40ns	6.0µs ±30ns	
For MF501B T1= 200 to 2100ns	
In use
Logical ‘0’ lights the LED. (MF503B & MF504B have option jumpers for LED lighting conditions).
Motor on
Logical ‘0’ turns the motor on. The write gate does not go to ‘0’ until 500mS after the motor on line goes to ‘0’.
Normal density (MF504B only)
Logical ‘1’ selects high density read/write operation and logical ‘0’ selects normal density. With option jumpers SS shorted and SB open, this line changes the motor rpm and read/write 'operations are performed 400mS after density change, to allow the motor speed to stabilize. When motor rpm is switched the head must be moved to track 00 before reading or writing. With SB shorted and SS open the motor speed is always 360rpm so no waiting or track 00 seek is necessary.
OUTPUT SIGNALS
Index
A ‘0’ pulse of 3.5mS is output once for each revolution of the disk.

Track 00
Logical ‘0’ on this line indicates that the head is on track 00.

Ready
This line is at ‘1’ if the door is opened or the lever is up. A ‘0’ is produced when the DC power is applied, a diskette is properly clamped and 2 or more index pulses are detected. Option jumpers select the type of ready signal supplied.
Read data
This line outputs raw data (combined clock and data signals) converted into logical ‘0’ pulses.

Type	T1	T2	T3	T4	
360rpm HD	2.0µs ± 400ns	4.0µs ± 800ns	3.0µs ± 600ns	300ns ± 150ns	
360rpm LD	3.33µs ± 66ns	6.67µs ± 1333ns	6.0µs ± 1200ns	300ns ± 150ns	
300rpm	4.0µs ± 800ns	8.0µs ± 16000ns	6.0µs ± 1000ns	300ns ± 150ns	
For MF503B T4= 1.0µs ± 250ns	
For MF501B T4= 0.8µs ± 250ns	HD – High density LD – Low density	
Write protect
This signal goes to ‘0’ when a write protected disk is inserted into the drive. Writing is inhibited even if the write gate is active.
Control and data timing

Note 1
Wait 8ms before issuing a step pulse after changing direction.

Note 2
Applies to MF504B at high density.

Disk Drive and front bezel dimensions

Test points for alignment procedures

	MF501B	MF503B	MF504B	
Track 00 sensor	TPA 1	TPA 1	TPA 4	
Read data output	TPA 3	TPA 3	TPA 3	
Track 00 output	TPA 13	TPA 13	TPA 2	
Index output	TPA 14	TPA 14	TPA 1	
Differential
head output	TPB 9
TPB 10	TPB 9
TPB 10	TPB 5
TPB 6	

Option jumper locations

Mitsubishi Electric (UK) Ltd., Hertford Place, Maple Cross, Rickmansworth Herts WD3 2BJ Tel 0923 770000 Tlx 296196 Fax 0923 777368