[pdp7-unix] ald

Bob Supnik bob at supnik.org
Mon Oct 21 11:45:01 AEST 2019

It's probably a CR01B; I doubt if Bell could afford a Type 421.

The CR01B was a complete POS. It sensed the punched holes with little 
mechanical fingers with starred wheels on the end that either went 
through and made contact (1) or did not (0). It required constant 
attention from Field Service.

Do we need a CR simulator? I fervently hope not.


On 10/20/2019 8:23 PM, Phil Budne via pdp7-unix wrote:
> Tom wrote:
>> Does anyone know what "ald" does?
> Looks to me like it's reading binary punched cards.
> It gets some card read-related system addresses,
> and defines an I/O instruction:
> crsb = 0706744
> which is defined on page 96 of
> http://www.bitsavers.org/pdf/dec/pdp7/F-75_PDP-7userHbk_Jun65.pdf
> to select card reader "column binary" mode, reading the rows of each
> column in as a 12 bit number.
> p
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