The 1442 card read-punch (pictured) was the 1130 System's low-cost punched card I/O option. Like the 1132 printer, it required significant CPU involvement: an interrupt was generated as each card column (80 per card) was read or punched. At the card reader's top speed of 400 cards per minute, this was more than 500 interrupts a second ... but dramatically less work was required per interrupt than with the 1132, and the CPU had no problem keeping up. CPU utilization was still significant, though, and card reading put a significant crimp into any computing activity going on. The 2501 card reader was available for those who required higher throughput or lower CPU utilization. It read cards at up to 1000 cards per minute, interrupting only once per card. With that small amount of CPU involvement, it was possible for an 1130 system with 2501 card reader and 1403 printer to read cards, do significant processing, and print the results as it went. |
