IBM 7090 User Manual

Op Decr Tag Adr
15
TRA
00004
16
LDQ
00004
17 HTR 00012
Read location from address part of MQ
20 HTR 00000
This program may be easily modified to allow it to search memory for a specific
address rather than for an operation code. The only change necessary is'to enter
instruction ALS 00025 in location 5 and instruction ARS 00025 in location 6.
7.2.02 Voltage
Proper sequence for bringing up power is:
1. Press power on reset key on 7618.
2. Reset MG CB1 on 7608.
3. Press power on switch on 7618 or 7151.
Note:
Failure to follow this sequence may cause a blown fuse in the 48-volt supply.
High resistant fuses or bad fuse clips may cause a voltage drop across the fuse large
enough to cause intermittent system trouble. A voltage drop of 0.1 volt across a fuse
indicates a defective fuse, fuse holder, or connection.
It is possible to have a power supply circuit breaker in an SMS frame partially open
without mechanically tripping the breaker. This may cause one phase to be lost to the
SMS frame power supply. A quick check for this condition is to observe the 400-cycle
volt meter on the 7618. This condition (loss of one phase in some power supply) will
usually be indicated by a larger spread in the voltage reading of the three phases. The
normal readings should be recorded for future reference. This procedure is not 100
per cent effective, but will detect a large percentage of single-phased power supplies.
When installing engineering changes, a periodic check of resistance between -6 and
ground will catch wiring errors, where the shield is tied to the wrong pin. Although
normal resistance is low when using a low scale on the ohmmeter, a change of resist-
ance will be indicated if an error is made.
Blower Motors
All blower motors, PiN 598593, in the 7090 system are 1/30 horsepower, with
exception of memory, which uses a 1/8 horsepower motor, P /N 598594. These blower
motors all rotate clockwise when viewed from the hinged end of the gate.
7.2.03 Adjustment of C Pulse Set (Figure 7.2-1)
General operation of a shift cell is described in Sec·tion 3. The setting and timing
of the C pulse set line is very important.
1. Make sure that the oscilloscope being used has probe leads of the same length.
2. Synchronize the scope on +N pulse at 02A2C15F on Systems 02.05.11.1. This
pulse is an A1D1 pulse. Check the following pulses; they should be 182 + 15 - 45
nanoseconds in duration, and should repeat themselves every 2.18 microseconds.
174

IBM 7090 Specifications

General

Category	Mainframe Computer
Introduced	1959
Transistor-based	Yes
Word Length	36 bits
Add Time	4.8 microseconds
Memory	Core memory
Memory (words)	32, 768 words