craig.umcp-cs@UDel-Relay@sri-unix (10/27/82)
From: Craig Stanfill <craig.umcp-cs@UDel-Relay> You have complained that your version of the TEK-4025 firmware is too slow to handle incoming cursor commands while you are typing. Is your host echoing your typing? If the host echos text from the keyboard inside of a cursor motion or other command the result will, of course, be garbled. By the way, I have a unix-to-tek synchronization filter; the TEK doesn't know the x-on/x-off protocol, but there are ways of synchronizing communication which partly make up for this problem. The terminal is slow, but this is less of a problem than two misfeatures in the firmware. 1. The screen may be divided into two regions, the Workspace and the Monitor. The Workspace has cursor addressing and special visual attributes; the Monitor has scrolling. Unfortunately, whenever the cursor is in the Workspace, text goes directly into the workspace, not the host. This makes the Workspace useless for most interactive tasks - editing, for example. It is possible for the Host to talk to the Workspace without displaying a cursor, but a display without a cursor is almost useless. The terminal is usable only because our visual editor ('vi') is smart enough to use the limited number of cursor motion commands which work in the monitor. 2. Visual attributes are done wrong. With most terminals, the host sends a command which means 'display all following text underlined', (or blinking, or reverse video, etc.). With the TEK 4025, you send a code which gets inserted in the screen, and means "underline from here to the next attribute code, or the end of the line." A program which is written assuming an interface similar to the 'normal' cannot be made to work; if underlined text spans two lines, the text on the second line will not be underlined. Programs which update the screen become unworkable; old attribute codes interfere with each other. Inserting a single underlined character in the middle of the screen may cause the rest of the line to become underlined. In fact, inserting a single underlined character in the display is safe only if you have a complete model of everything that has been done to the screen. This problem is a result of hardware decisions, but the firmware could have compensated for the hardware design. I would like to know exactly how tektronix came up with the interface to this terminal. I tend to think they didn't do much homework. They should have taken care not to write firmware which made their terminal incompatable with most software.