CD11 High-Speed Punched Card Reader Control Unit

The CD11 High-Speed Punched Card Reader Control Unit was a UNIBUS device controller for the CR04 punched card reader. It used DMA to transfer data.

Registers

The controller has four control and buffer registers, which can be configured to any four sequential word locations in the I/O page; it is normally configured to addresses 772460-774666:

Register	Abbreviation	Address
Status and Control Register	CDST	772460
Column Count Register	CDCC	772462
Current Address Register	CDBA	772464
Data Buffer Register	CDDB	772466

In the register contents (below), bits which are read/write or unused are shown in normal font, those which are read-only are in italics, and write-only in bold.

Status and Control Register (CDST)

ERR	HDR CHK	EOF	OFFLINE	DATA ERR	DATA LT	NXM	PWR CLR	RDY	INT ENB	EXT BUS ADDR		RDR ONLINE	HOPPER CHECK	DATA PACK	READ
15	14	13	12	11	10	09	08	07	06	05	04	03	02	01	00

Column Count Register (CDCC)

CC15 <---> CC00
15	14	13	12	11	10	09	08	07	06	05	04	03	02	01	00

Current Address Register (CDBA)

BA15 <---> BA00
15	14	13	12	11	10	09	08	07	06	05	04	03	02	01	00

Data Buffer Register (CDDB)

The format of the contents this register depends on the setting of the 'Data Packing' bit in the CSR. If 0, '12-bit word', it holds 12-bit raw data from the card:

Unused				Zones 12-11		Zones 0-9
15	14	13	12	11	10	09	08	07	06	05	04	03	02	01	00

If 1, '8-bit byte', it holds the compressed Hollerith code (zones 1-7 can have only a single punch, which is encoded in octal in 3 bits; a '0' means 'no punch in any of these'):

Unused								Zone 12	Zone 11	Zone 0	Zone 9	Zone 8	Code Zones 1-7
15	14	13	12	11	10	09	08	07	06	05	04	03	02	01	00

Implementation

It was constructed from a number of smaller FLIP CHIPs which were installed in custom 4-slot system unit backplane. The modules are:

• M112 - 10 x 2-input NOR gates
• 2 x M113 - 10 x 2-input NAND gates
• M117 - 6 x 4-input NAND gates
• M203 - 8 x 'S-R' flip-flops
• M205 - 5 x 'D' flip-flops
• M239 - 3 x 4-bit counter/register
• M304 - One-shot delay
• M611 - High speed power inverters
• M721 - Bus interface
• M7249 - Hollerith check
• M783 - Bus drivers
• M784 - Bus receivers
• M796 - UNIBUS Master Control
• M7821 - Interrupt Control
• M957 - Ribbon cable connector
• M7219 - Bus Interface

The M7219 is a quad card; the others are all single. (Of those, the M783, M784, M796, M7821 and M957 are extended length; most of the others are all standard length.)

Board locations (as seen from the board insertion side of the backplane, not the wire-wrap pin side, as is common in DEC documentation) are:

	Connector
Slot	A	B	C	D	E	F
1	UNIBUS In		M7219
2	M721	M957	M784	M783	M7821	M796
3	M113	M239	M7249	M611	M117	M205
4	UNIBUS Out		M113	M112	M304	M203

External links

• pdp11 peripherals handbook (1976) - the CD11 is covered on pp. 60-72 of the PDF
• KS10-Based DECSYSTEM-2020 Technical Manual (EK-0KS10-TM-002) - the CD11 is covered on pp. 22-25 of the PDF