Editing IBM 1620 (section)

===Disk drives===
[[File:BRL64-IBM 1311 DiskDrives.jpg|thumb|IBM 1311 Disk Drives{{snd}} Model 2 (Slave) & Model 3 (Master), attached to an IBM 1620 II]]
The [[IBM 1311|1311]] Disk drive controls.

* Module light – This light shows the drive number. When it lights the drive is ready for access.
* Compare-Disable key-switch – When this (Master only) switch is in the ON position and the Write Address button is pressed a full track write may be performed without comparing addresses. Used to format disk packs.
* Select Lock light – When this (Master only) lights one or more of the drives has malfunctioned. No disk access can be performed.
* Write Address button/light – This (Master only) key controls writing sector addresses. Pressing it toggles this enable and turns its light on/off.
* Enable-Disable toggle-switch – This switch enables or disables access to the drive. If this switch is disabled on the Master, all drives are disabled regardless of the state of their own switches. Also controls the disk usage time meter(s).
* Start Stop button – Pressing this key starts or stops the disk drive motor. The motor must be stopped to open the lid and change disk packs.
{| class="wikitable"
|-
!Bootstrap procedure
!Notes
|-
|Press ''Insert''
|Unlocks typewriter keyboard and shifts into numeric mode.
|-
|Type 3400032007013600032007024902402<br/>x<br/>y1963611300102
|x{{snd}} Specifies source of Monitor control cards: 1=typewriter, 3=paper tape, 5=cards<br/>y{{snd}} Specifies disk drive on which Monitor resides: 1, 3, 5, 7<br/>02402 is the address of the entry point of the Monitor program.
|-
|Press ''Release''
|Locks typewriter keyboard.
|-
|Press ''Start''
|Begin execution.
|}

{| class="wikitable"
|-
!Restart procedure
!Notes
|-
|Press ''Insert''
|Unlocks typewriter keyboard and shifts into numeric mode.
|-
|Type 490225<sup>FLG</sup>6<br/>&nbsp;
|02256̅ is the address of the location containing the address of the restart point of the Monitor program.<br/>Note: this procedure assumes the Monitor is already loaded in memory
|-
|Press ''Release''
|Locks typewriter keyboard.
|-
|Press ''Start''
|Begin execution.
|}