IBM System/360 2050 User Manual

FUNCTIONAL UNITS
Sequence Counter
The sequence counter, in combination with the se-
quence stats, controls the operations performed in
sequence counter mode (FLT load and logout opera-
tions). In MS mode, the sequence counter controls
the logout of ROS DR and ROAR. In ROS mode, if
the supervisory stat is on, the sequence counter
determines how many ROS words (microinstructions)
are executed under control of the current linkage
control word.
The counter equals all zeros when reset off.
Microorder E - SCANCTL, Lr!. combination with
EMIT 1000 (QY110-C5), sets the 2' s complement of
SDR(0-2) into the sequence counter indicators (4, 2,
1). See Figure 9, Sequence Counter Logic Chart.
The sequence counter is stepped (incremented) by
the same control line that sets it (clocked sequence
counter select -- KH351).
Sequence Stats
The sequence stats, in combination with the sequence
counter, control the operations performed in se-
quence counter mode.
FLT Op Reg
The FLT op reg controls most main store mode
operations by decoding the SDR parity bits. It also
controls many ROS mode operations after being set
by the microorder SCAN * E, 00 (or 10) in combi-
nation with the emit field bits. Instructions decoded
by the FLT op reg are shown on Figure 10. This
register, used with general purpose stats 0-3, forms
the scan/log decoder (Figure 11).
Scan/Log Decoder
The scan/log decoder is composed of the FLT op
reg and general purpose stats 0-3 (Figure 11). This
decoder controls the operations performed during a
scan-out or logout. Figure 12 shows the data and
storage locations used during a log or scan-out op-
eration. Figure 13 is a log/scan-out logic diagram.
ROS Kernels
ROS kernels are special maintenance routines (con-
sisting of one or many microinstructions in ROS)
that are used by FLT's, progressive scan, error
logouts, and the diagnose instruction, etc. Figure
14 is a listing of the ROS kernels. Figure 15 is the
ROS kernels flowchart.
Scan-In
The scan-in kernel (maintenance routine) takes up to
l 1 words from storage, putting them into various
CPU counters, registers, and stats. These words,
in consecutive storage locations, may be started
from any desired address. The scan-in kernel is
used by FLT's and progressive scan, and may also
Input Value
SDR (0,1,2)
Fint *PH
Second *PH
{Input Volue Minus lj
Seq Ctr Indicators (4,2, l) Seq Ctr Bit
(l '~ Comp! of Input)
(2's Compl of Input) (line Nomes on KH341)
I 1
1
Seq Ctr
_J_=·-~ ---L---~~- ~- _J ____ ~~------- __ JiL ___ __.._~~ ___
0
__ _,
2 = l I Off i Off I On l
l = 0 On j Off 2 On 2
0 = 0 , On Off 4 On 4
2 = 0
1=1
O=O
2=0
l = 0
0 = l
2 = l
l = 0
O=I
2=0
l = l
0 = 1
----r---------+-
On On l Off I
Off Off 2 On 2
On ____ _,_ ___ O_ff _____ _,__ __ 4_0_n ____ -+-_4~---6---<
Off Off 1 On 1
Off Cn 2 Off 2
~ 00 40n
On On 1011
On On 2011
Off Off 4 On
Off Off l On
~ 00 20n
Off On 40ff
On
Off
Off
Off
Off
Off
On
Off
On
Off
On
On
1 OFF
2 On
4 Off
1 On
2 OFF
4 Off
l
2
4
l
2
4
I
2
4
l
2
4
FIGURE 9. SEQUENCE COUNTER LOGIC CHART
Maintenance Features (3/71) 21

IBM System/360 2050 Specifications

General

Brand	IBM
Model	System/360 2050
Category	Computer Hardware
Language	English