Standard NORD-1 card format

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All cards in the NORD-1 CPU and I/O crate share a standard card format. It is most probably also used in the NORD-2B and NORD-4 CPU:s too.

Component side.
Component side of the 151 Time counter card.

Introduction

The card is 156x127 mm in size with a protruding edge contact 8x122 mm. The gold plated edge contact have 30 contact points per side with 1 and 59 holding VCC at +5V and GND at 2 and 60.

The card has a common set of via holes in a fixed pattern of 20 rows of 48 holes. What differentiates the various cards is the wiring between the edge contacts and the via holes.
There are no solder mask or silk screen on the cards so components are identified by their position in a grid format of A-D and 1-19. The rows are printed on the cards but not the columns where A is the first column closes to the edge contact and D is the one at the front of the card crate. In logic drawings the coordinates and pin numbers are marked on the logic symbol.
Circles with a number in it is the edge contact.

The maximum numbers of IC:s on a board is 32.

Reference