The NCR 605 Minicomputer
NCR 605 Peripherals and Data Network
The 656-401 Disk Drive
The 656 disk drive used on the 725, 726 and T8270. The early 725s and 726s used a 651 drum memory for high speed interactive item lookup.
The Hewlett Packard Tape Drive
The Hewlett Packard tape drive was used on some of the 725s. The other drive used was the CDC unit that had vacuum chambers to control the tape loops. My preference was the Hewlett Packard but spent many hours working on the CDC units. The tape drive was the POS data collection output so if the drive was down the 751s in the stores backed up the data on cassette tapes.
Codex 2640 Modem
In the early days of the 725 and 280s, NCR 1200 baud modem cards were used in the 725 card racks. Later on when the terminals like the interactive 2151 were used faster data speed was needed. Sync adapter boards were used that connected to external modems that had built in multiplexers. The early Codex modems provided four 2400 BPS channels on one 9600 data line. In the late 80s the Codex came out with the 19.2 BPS modem giving 4800 PBS per channel.
Codex Network Drawing
The typical external modem multiplexer configuration with main frame connection for reporting.