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Buffer Capacity
I
Note
I
1-8 General Information
The HP 27140A uses a 4Kbyte buffer to temporarily store data to be sent
to the host computer. Because of the distinctive system used to identify
each character received, this capacity provides actual character storage
equal to lKbyte. Buffer space is dynamically allocated to the six ports as
they require it. Thus, no one port has specific buffer address space dedi-
cated to it. This buffer capacity limits the throughput of the MUX. Table
1-1 lists four possible combinations of baud rates for the HP 27140A.
Table 1-1. ButTer Capacity Baud Rate Limits
Port
Baud Rate
1
2
3
4
0
19200
19200
19200
9600*
1
4800*
19200
19200
9600*
2
4800*
19200
2400*
9600*
3
4800*
unused
2400*
9600*
4
4800*
unused
2400*
9600*
5
4800*
unused
2400*
9600*
*Slower rates may be used.
All of these speeds assume full duplex operation and near 100% utiliza-
tion of channel capacity. Operation at higher speeds than noted may
result in DATA OVERRUN errors.
When all six terminals are being used by people in interactive programs, it
is unlikely that the users could overload the buffer, since human beings do
not enter data rapidly enough to use the potential of 19200 baud. In this
case, all six ports could be programmed to 19200.
Update 1 (October 1988)
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