Where should the type information be 144

Brian Inglis interconvert

some of this may be my fault. three people came out from CSC the last week of january, 1968 to install cp67 at the university. at that time, cp67 only contained 1052 & 2741 terminal support. I had to add translate tables from BTAM ... and tweaking them to make them more conducive for cp67 operation.

one of the cp67 characteristics was terminal character & line delete operation. on the right side of 2741 keyboard, there is key with at-sign lower-case and cent-sign as upper-case. the convention in cp67 was that at-sign (lowercase key) deleted the next character to the left (already entered) ... multiple at-signs would delete multiple adjacent characters (already entered on the left). The cent-sign (uppercase on the at-sign key) would delete all characters to the left (already entered, to start of line).

i don't have reference right now ... but from vague memory ... i believe tty-33 had left-right brackets in approx. same position on the keyboard (so i fiddled the translate tables based on that).

the standard cp67 code had dynamic terminal identification for 1052 & 2741 (you didn't have to make fixed terminal type definitions buttociated with specific terminal controller port). I thot that i was going to be fancy and do the same thing when adding tty support. i also thot that i could have a single dial-up number for modem pool ... so all terminals could dial-in on the same number.

The dynamic terminal identification worked ... but the dial-in part didn't. While the code could dynamically determine the connected terminal ... the standard mainframe terminal controller interface couldn't handle the general case of arbitrary terminal connecting to an arbitrary controller port.

The terminal controller did have "SAD" command support so that an arbitrary line-scanner could be buttociated with an arbitrary port. The problem was that they had hardwired oscillators on each port ... which fixed the port baud rate. As long as different terminals shared the same baud-rate ... it was possible to use the "SAD" command support to buttociate the appropriate line-scanner with a port (which is why the 1052 & 2741 terminal support worked ... they had different controller line-scanner ... but the same baud rate).

Adding TTY support ... it was possible to dynamically define the terminal type (w-o requiring predefined terminal tables) ... but it wasn't possible to actually dynamically intermix connection of terminals with different baud rates on the same port.

this somewhat kicked off the clone controller project

where the mainframe channel interface was reversed engineered and a channel interface board built for an Interdata-3 ... and the Interdata-3 was programmed to emulate the ibm mainframe controller. In the interdate-3 impementation ... support was added to do high-speed probe of in-coming signal on ports to dynamically determine connecting terminal baud rate.