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Device
3203
I
3204
3231 9
3232 4 ,9
3325
3335
7202
7203
7204
7232
7246 3 ,9
7251 4
7315/16
7362
7372
Notes:
- - - - -
Table 3. Comparison of Secondary Storage Devices
lOP Bandwidth
2
Requirements
Sigma 3
1
Average
Maximum
Blocking
Capacity
Access Time
Transfer Rate
530
IIOP
EIOP
Buffer Size
1.3 mb
8.5 ms
755.2 kb
100%8
NA
NA
128 words
2.6 mb
8.5 ms
755.2 kb
100%8
NA
NA
128 words
2.4 mb
50 ms
312 kb
36%
NA
NA
128 words
4.9mb
50 ms
312 kb
36%
NA
NA
128 words
23mb (l'80<hpi 5
8.8 ms
36 kb
6%
NA
NA
NA
46mb rt1600bpi5
B.8
ms
72 kb
11%
NA
NA
NA
.75 mb
16.9 ms
187.5 kb
45%
35%
35%
180 words
1.5 mb
16.9 ms
187.5 kb
45%
35%
35%
180 words
3.0 mb
16.9 ms
187.5 kb
45%
35%
35%
180 words
6.3 mb
16.9 ms
384 kb
NA
78%
72%-600k
512 words
24.5 mb
87.5 ms
312 kb
77%-52%
59%
59%-49%
512 words
2.3 mb
50.5 ms
312 kb
78%-57%
NA
NA
180 words
23mb U80<hpi
5
5rns
60 kb
18%
13%
13%
NA
. 16mb u556bpi 5
1O.n1s
20 kb
8%
7%
7%
NA
23mb u80Obpi 5 , 6
5 ms
60kb
7
NA
12%
12%
NA
1.
RBM requires approximately .36-.56 megabytes for system storage, including standard processors.
2.
RBMdoes not manage bandwidth control, thus the installation must be properly configured to avoid
data
overruns~
When two figures are shown, the second figure indicates bandwidth requirements
when the two-byte interface is included; this figure is not shown if not applicable.
.
3.
RBM treats each 7242 as two 7246 disk packs.
All disk packs except the system-residence pack
may be declared to be removable.
4.
Each 7252 is treated as two 7251 devices. Each
j13.;·)
is treated as two 3232 devices.
5.
Assuming 240D-foot reels andnointerrecord gaps.
Reduce this figure by the percentage of
the tape required for interrecord gaps.
This value is a function of record size since gap is
fixed (0.75 inches for 7362/72; 0.5 to 0.75 inches (average 0.6 inches) for 7315/16; 0.6
inches for 3325/35).
6.
Model 7372 transfers six bits of information. per byte.
7.
Model 7372: reduce transfer rate by 25 percent for packed binary mode.
8.
Requires dedicated IOP2.
9.
Any device controller which is capable of performing seek overlap cannot share a channel
with any other device controller.
Secondary Storage Requ i rements
7
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