DC319 DLARTs and T11s (was T-11 ....)

Bob> If you can't find a DC319, then the alternative is to build a Bob> DL11 compatible interface using a standard UART like the 6402 Bob> and a handful of discrete logic. I think the minimum you could Bob> get away with would be to implement the DONE and INTERRUPT Bob> ENABLE bits (bits 6 and 7) for both the receiver and transmitter Bob> CSR, and then to implement the standard vectors at 60/64. Oh, Bob> and of course the data registers for the transmitter and Bob> receiver. Bob> The KL11 also implements a MAINTENANCE bit, a BUSY bit, and a Bob> READER ENABLE bit, but a) we have no reader, b) I doubt (I'm Bob> hoping) much software ever looks at the BUSY bit, and c) Bob> probably nothing uses the MAINTENANCE bit except the Bob> diagnostics. Bob> ISTR that DEC had an "official" standard written down for Bob> exactly what was required of a DL-11 compatible serial Bob> interface, but I can't find it anywhere. The approach you described should do the job. If all you need is compatibility with console boot drivers, you could leave off the interrupt machinery since those things tend to run in polled mode. But for an OS you'd need IE and the interrupt. And if you want to ignore inbound errors, you need only implement the low byte of the receive data register. This would be a nice small VHDL exercise... paul