The 2100A was 16-bit computer, and was the replacement for the HP 2116C in 1971. It uses the same IO cards as the 2116C, and had 14 IO channels as default, expandable up to 45. The 2100A replaced the previous 2116, 2115 and 2114 models.
The 2100A had several new features; Dual Channel DMA, Memory Protect, and an option for a Floating Point card. The system came with 4kWords of Magnetic Core memory as standard. This could be upgraded to 32kWords.
According to the HP Museum, Over 8,000 units of 2100A and 2100S computers were sold by the time the machines were obsoleted in April of 1978.
The 2748B Paper Tape Reader was designed for use with this computer and other HP computers in the range.