LH-DH/11 Local/Distant Host Controller

The LH-DH/11 Local/Distant Host Controller is a DMA UNIBUS IMP interface produced by ACC to allow a UNIBUS machine to connect to an ARPANET IMP.

It consists of a 10-1/2" rack mounting box holding a pair of wire-wraped boards (one for packet input, and one for output), holding a number of SSI TTL integrated circuits; there is also an internal power supply. Level converters allow use as either a Local Host or Distant Host interface; BC11A cables connect it to the rest of the system.

Registers

Register	Abbreviation	Address
Control & Status In Register	CSRI	0767600
Data Buffer In Register	DBRI	0767602
Current Word Address In Register	CWAI	0767604
Word Count In Register	WCI	0767606
Control & Status Out Register	CSRO	0767610
Data Buffer Out Register	DBRO	0767612
Current Word Address Out Register	CWAO	0767614
Word Count Out Register	WCO	0767616

0767600: Control & Status In Register (CSRI)

ERR	NXM	EOM	Unused	HR	INR	RMRE	IDBF	RDY	IE	XBA16-17		SENB	HRC	IRST	GO
15	14	13	12	11	10	09	08	07	06	05	04	03	02	01	00

0767602: Data Buffer In Register (DBRI)

Data15 <---> Data00
15	14	13	12	11	10	09	08	07	06	05	04	03	02	01	00

0767604: Current Word Address In Register (CWAI)

WA15 <---> WA00
15	14	13	12	11	10	09	08	07	06	05	04	03	02	01	00

0767606: Word Count In Register (WCI)

WC15 <---> WC00
15	14	13	12	11	10	09	08	07	06	05	04	03	02	01	00

0767610: Control & Status Out Register (CSRO)

ERR	NXM	WC0	Unused			TMRE	ODBE	RDY	IE	XBA16-17		BBM	ELB	IRST	GO
15	14	13	12	11	10	09	08	07	06	05	04	03	02	01	00

0767612: Data Buffer Out Register (DBRO)

Data15 <---> Data00
15	14	13	12	11	10	09	08	07	06	05	04	03	02	01	00

0767614: Current Word Address Out Register (CWAO)

WA15 <---> WA00
15	14	13	12	11	10	09	08	07	06	05	04	03	02	01	00

0767616: Word Count Out Register (WCO)

WC15 <---> WC00
15	14	13	12	11	10	09	08	07	06	05	04	03	02	01	00

External links

• Local/Distant Host Controller LH-DH/11C and LH-DH/11B Maintenance Manual