13-Bit ANR Word Compression and Expansion Techniques
Original Publication Date: 1984-May-01
Included in the Prior Art Database: 2005-Feb-03
Emulation of the IBM 3277 terminal with an 8-bit microprocessor involves the solution of some special problems. These result because the 3277 data interface (ANR) uses 13-bit control and data words, while the microprocessor has only 8 bits to work with. A hardware adapter card was built to perform the functions of several of the bits of the 13-bit words, such as read, write, and cursor position control. The rest of the required functions can be controlled by a software program in the microprocessor. These functions require translation of all data fields to and from the data code used by the device the data is to be sent to, i.e., keyboard, display screen, etc. The overall dataflow is shown in Fig. 1. As noted, ANR words consist of 13 bits of data.