IBM 2501
| Company type | Product |
|---|---|
| Industry | Computer hardware |
| Fate | Discontinued; emulated in software |
Area served | IBM System/360, System/370, System/360 Model 20, IBM 1130, IBM System/3 |
| Products | Punched card reader (80-column cards) |
| Owner | IBM |
| Parent | IBM |
The IBM 2501 is a punched card reader created for use with IBM's System/360 and System/370 mainframe computers, in addition to the IBM System/360 Model 20, IBM 1130, and IBM System/3 minicomputer series. It processes 80-column punched cards at rates of either 600 or 1000 cards per minute (CPM).
Although no longer produced, the 2501 continues to be emulated through software on contemporary IBM platforms.
Models
There are four variants of the 2501, distinguished by their reading speed and whether they include an integrated control unit. Models designed for mainframes feature a built-in control unit, eliminating the necessity for a separate external one.
| Model | Speed (CPM) | Integrated control unit? |
|---|---|---|
| A1 | 600 | no |
| A2 | 1000 | no |
| B1 | 600 | yes |
| B2 | 1000 | yes |
The A1 and A2 versions are specifically intended for the IBM 1130 system.
Usage
The 2501 utilizes photoelectric sensing technology to read each punched card sequentially, column by column, following a simple card feed path. To guarantee reading precision, each column undergoes two passes.
In mainframe environments known as "open shop," the 2501 was frequently employed to handle job inputs submitted by users. Within the IBM 1130 setup, it acted as a faster alternative to the IBM 1442 reader, effectively doubling card reading speed while lessening CPU workload. For the System/3, which normally uses 96-column cards, the 2501 provided an option to process standard 80-column punched cards.
Features
An optional special feature (RPQ) exists across all models that permits reading of optically marked cards using (OMR) technology.