Re: Times change
The 2400 baud sort of gives it away that that was in the days before zmodem allowed a transmission resume.
AFAICR, some time between late 1983 and early 1985, based on where each of us was living (he wasn't a direct friend of mine, but we had a common connection). So indeed before ZModem, and Wackypedia tells me 2400baud was Brand Spanking New in 1984 so that fits too.