IBM System/370

Page of GC20-1730-0
Revised 11/20/70
By TNL GN20-2277
3. A seven-channel system including two 2870 Multiplexer and five
2880 Block Multiplexer channels with maximum aggregate data rate
of approximately 6.8 ME.
Channel
Channel Channel
I/O
Data Rate
Priority
Address Type Device in MB
1
1
2880
230"
Model
1
3.0
2 0 2870
2401
Model
6 SSCl .180
2401 Model
6 SSC2 .180
2401 Model 6 SSC3 .180
2401
Model 3 SSC4 .090
MPX .027
.660
3
2
2870
2401 Model
6 SSCl
.180
2401 Model
6 SSC2
.180
MPX .040
.400
4
3
2880 3330 facility .806
5
4 2880
3330
facility
.806
6
5
2880 3330 facility .806
7
6 2880 2314
or 3420
Model 7
.320
4. A twelve-channel system including one 2870 Multiplexer and
eleven 2880 Block Multiplexer channels with a maximum aggrega"ce
data rate of approximately 9.4 MB.
Channel
Channel Channel
I/O
Data Rate
Priority
Address Type Device in MB
1 8 2880 2305 Model
1
3.0
2
9
2880 2305 Model
2
1.5
3 0 2870 Multiplexer aggregate .560
4
10 2880 3330 facility .806
5
11
2880 3330 facility .806
6
1
2880
3330 facility .806
7
5
2880
2314 or 3420
Model 7
.320
8
3
2880 2314 or 3420
Model 7
.320
9 4 2880
2314 or 3420
Model 7 .320
10
2 2880 2314
or 3420
Model 7 .320
11 6 2880 2314
or 3420
Model 7 .320
12 7
2880
2314
or 3420
Model 7 .320
The Model 165 with a 2 microsecond processor storage is able to
achieve higher aggregate data rates than the Model 65 with a .750
microsecond main storage because Model 165 operations have been designed
to optimize the use of four-way doubleword interleaving by use of more
I/O buffering. Additional channel buffers are provided in the Model
165 CPU and the 2880 channel, which permit effective use of interleaving
during I/O operations and help prevent data overrun when peak activity
occurs.
The storage control unit contains four dedicated 8-byte buffers
for each channel that are assigned when the channel is installed.
In addition, each 2860 Selector Channel contains two 8-byte buffers,
and a 2880 Block Multiplexer Channel contains two 16-byte buffers or
four 16-byte buffers depending on its maximum rate, 1.5 MB or 3 MB.
27