RX11 floppy disk controller

The RX11 and RXV11 are controllers for the RX01 floppy disk drives for the UNIBUS and QBUS.

They have an identical programming interface; both use programmed I/O. The controller contains a buffer, which is filled or emptied under program control.

Device registers

Register	Abbreviation	Address
Command and Status Register	RXCS	777170
Data Buffer Register	RxDB	777172

777170: Command and Status Register (RXCS)

Error	Initialize	Unused						Transfer Request	Interrupt Enable	Done	Unit Select	Function			Go
15	14	13	12	11	10	09	08	07	06	05	04	03	02	01	00

Setting the 'Initialize' bit does not clear the 'Interrupt Enable' bit on the RXV11.

The function codes are:

Code	Function
0	Fill Buffer
1	Empty Buffer
2	Write Sector
3	Read Sector
4	Not used
5	Read Status
6	Write Deleted Data Sector
7	Read Error Register

777172: Data Buffer Register (RXDB)

This register contains one of several 'virtual' registers, depending on the function in progress.

The 'Transfer Request' bit in the RXCS is used to indicate which virtual register is in used at any given time.

Track Address (RXTA)

Unused								0	Track
15	14	13	12	11	10	09	08	07	06	05	04	03	02	01	00

Sector Address (RXSA)

Unused								0	0	0	Sector
15	14	13	12	11	10	09	08	07	06	05	04	03	02	01	00

Data Buffer (RXDB)

Unused								Data
15	14	13	12	11	10	09	08	07	06	05	04	03	02	01	00

Note the name clash between this virtual register, and the actual register which contains it.

Error and Status (RXES)

Unused								Drive Ready	Deleted Data	Unused			Initialize Done	Parity Error	CRC Error
15	14	13	12	11	10	09	08	07	06	05	04	03	02	01	00