IBM System/360 65 - 2065 INSTRUCTION BUFFER REFILL

10
D
R~I
[
Ie
~I
21 22
NEOP
BEOP
NOTE,
Early storage requests are
dependent on fonnet and
on initial position of op-code
halfword in Q, as shown below.
RR
RX
RX
R5
R5
51
51
55
55 55
10
Q
15 16
31 32 4748
15
10 ~I
01
7
Op-code bits
Decode
Bits
21, 22
R~I
63
Fonnat
Decoder
Branch
Decoder
00
01
OR
10
RX, RS, or SI
55
Not branch
Execute not in progress
Function
2065 INSTRUCTION BUFFER REFILL
ALD
3-cycle storage
request (per I C)
Start I-Fetch
sequencers
4-cycle storage
request (per IC)
Decoding of Ie or 0 bits (21, 22) DR061
Storage request logic KDIOI, KD201
Format decoding
RROOI
Branch decoding RRIBI
S/360 MODEL 65 29