On Mon, Oct 17, 2016 at 1:11 PM, Kurt McCullum <kurt.mccul...@att.net>

> John, Thanks for info. Is that a TELCOM limit? The reason I ask is because
> when running virtual T with TS-DOS, I notice that the buffer can go to 255.
> Or at least the byte which holds the buffer size.
In my experience I've found that all 8-bit bytes go to 2^8 - 1 = 255

Just teasing :-) It could but it should never in practice have a value > 64.
Have you observed a higher value than 64?

It's not a limitation of TELCOM per se, it's a limitation of the receive
interrupt handler logic and the size of the circular queue-on-array
reserved for receiving bytes. The same receive handler is used for TELCOM
and BASIC access to the serial port.

See http://www.club100.org/ftp/m100-hiddenpowers-3.pdf
Page 186

It shows a receive buffer of 64 bytes. If it went beyond the bounds,
unmasked, I would expect it to corrupt other data structures.

The high-water mark for the buffer is 40 (the point at which the receive
handler sends XOFF), which probably makes more sense in the context of a 64
byte buffer than a 255 byte buffer :-)

-- John.

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