RFC 205 (rfc205) - Page 2 of 13
NETCRT - a character display protocol
Alternative Format: Original Text Document
RFC 205 NETCRT - A CHARACTER DISPLAY PROTOCOL 6 August 1971 NETCRT PROTOCOL - VERSION 3 A. INTRODUCTION The UCLA Campus Computing Network (CCN) node intends to provide Network access to its conversational remote job entry system URSA. The URSA system is display-oriented, supporting only character displays with local buffers (originally IBM 2260 displays, now CCI 301 TV display consoles). This document defines a third-level protocol called NETCRT which allows a Network user in a remote Host to look like a CCI console to URSA. NETCRT is defined in terms of a virtual character display ("VCD") terminal, simulated by a process in the user host. URSA, like many on-line console systems, attempts to provide a good man/machine interaction by keeping tight control over the state of the terminal. On the other hand, the Network Working Group has deliberately built some "squishiness" into the standard Network protocols. We believe this squishiness is a conceptual mistake when dealing with remote man/machine interaction, and we would support protocol revisions to allow control over the effective communication compliance between processes in different hosts. However, this NETCRT protocol attempts to cope with the present squishiness, which is apparently built into a number of host's NCPs. In fact, we have arranged things so a host can improve response time and reduce Network traffic with NETCRT by using the message buffering inherent in his NCP. B. THE VIRTUAL CHARACTER DISPLAY A VCD consists of the following virtual hardware (see Figure 1): 1. A rectangular _display screen_ capable of displaying N lines of M characters. 2. A _local buffer_ of M x N characters used to refresh the display. 3. A _cursor register_ which addresses the characters in the buffer (and hence on the screen). This register controls the writing of text into the local buffer from either the keyboard or the server, and the reading of the local buffer by the server. 4. A _keyboard_ containing text keys and control keys. Each text key enters a character into local buffer at the current cursor address and steps the cursor register by 1. Braden
