View source for 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 [[Direct Memory Access|DMA]] to transfer data.

==Registers==

The controller has four control and [[buffer]] [[register]]s, which can be configured to any four sequential [[word]] locations in the I/O page; it is normally configured to [[address]]es 772460-774666:

{| border=1
! 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)===
{{16bit-header}}
| ''ERR'' || ''HDR CHK'' || ''EOF''|| ''OFFLINE'' || ''DATA ERR'' || ''DATA LT'' || ''NXM'' || '''PWR CLR''' || ''RDY'' || INT ENB || colspan=2 | EXT BUS ADDR || ''RDR ONLINE'' || ''HOPPER CHECK'' || DATA PACK || '''READ'''
{{16bit-bitout}}

===Column Count Register (CDCC)===
{{16bit-header}}
| colspan=16 | CC15 <---> CC00
{{16bit-bitout}}

===Current Address Register (CDBA)===
{{16bit-header}}
| colspan=16 | BA15 <---> BA00
{{16bit-bitout}}

===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:
{{16bit-header}}
| colspan=4 | Unused || colspan=2 | ''Zones 12-11'' || colspan=10 | ''Zones 0-9''
{{16bit-bitout}}

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'):
{{16bit-header}}
| colspan=8 | Unused || ''Zone 12'' || ''Zone 11'' || ''Zone 0'' || ''Zone 9'' || ''Zone 8'' || colspan=3 | ''Code Zones 1-7''
{{16bit-bitout}}

==Implementation==

It was constructed from a number of smaller [[FLIP CHIP]]s 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-flop]]s
* 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
* [[M782 Interrupt Control|M7821]] - [[Interrupt]] Control
* M957 - [[Ribbon cable]] connector
* M7219 - Bus Interface

The M7219 is a [[DEC card form factor|quad]] card; the others are all single. (Of those, the M783, M784, M796, M7821 and M957 are [[DEC card form factor|extended length]]; most of the others are all standard length.) <!-- The M239 is used to hold the Command and Status Register. -->

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:

{| class="wikitable"
! !! colspan="6" | Connector
|-
! Slot !! A !! B !! C !! D !! E !! F
|-
| 1 || colspan="2" style="text-align:center;" | UNIBUS In || colspan="4" style="text-align:center;" | M7219
|-
| 2 || M721 || M957 || M784 || M783 || M7821 || M796
|-
| 3 || M113 || M239 || M7249 || M611 || M117 || M205
|-
| 4 || colspan="2" style="text-align:center;" | UNIBUS Out || M113 || M112 || M304 || M203
|}

==External links==

* [http://www.bitsavers.org/pdf/dec/pdp11/handbooks/PDP11_PeripheralsHbk_1976.pdf pdp11 peripherals handbook (1976)] - the CD11 is covered on pp. 60-72 of the PDF
* [http://www.bitsavers.org/pdf/dec/pdp10/KS10/EK-OKS10-TM-002_tech_Sep79.pdf KS10-Based DECSYSTEM-2020 Technical Manual] (EK-0KS10-TM-002) - the CD11 is covered on pp. 22-25 of the PDF

[[Category: UNIBUS Peripherals]]