Editing IBM 1620 (section)

==Models I and II consoles==
While the ''Lower console'' for both the Model 1<ref name=ModOne.1620>{{cite web
   |url=https://www.bitsavers.org/pdf/ibm/1620/A26-5706-3_IBM_1620_CPU_Model_1_Jul65.pdf
   |title=IBM 1620 Central Processing Unit, Model 1
   |page=28
   |access-date=2017-12-18
   |archive-url=https://web.archive.org/web/20171009212302/http://www.bitsavers.org/pdf/ibm/1620/A26-5706-3_IBM_1620_CPU_Model_1_Jul65.pdf
   |archive-date=2017-10-09
   |url-status=dead
   }}</ref> and the Model 2<ref name=ModTwo.1620>{{cite web
   |url=https://www.bitsavers.org/pdf/ibm/1620/A26-5781-2_IBM_1620_CPU_Model_2_Nov65.pdf
   |title=IBM 1620 Central Processing Unit, Model 2
   |page=71
   |access-date=2017-12-18
   |archive-url=https://web.archive.org/web/20190525180847/http://bitsavers.org/pdf/ibm/1620/A26-5781-2_IBM_1620_CPU_Model_2_Nov65.pdf
   |archive-date=2019-05-25
   |url-status=dead
   }}</ref> IBM 1620 systems had the same lamps and switches, the ''Upper console'' of the pair were partly different.

===Upper console===
{| class="wikitable" border="1"
! class="unsortable"|'''Model I''' (Upper console)
| class="unsortable"|#Lamps
! class="unsortable"|'''Model II''' (Upper console)
| class="unsortable"|#Lamps
|-
| Instruction and Execute Cycle 
| 60
| Control Gates 
| 60
|-
| Control Gates
| 35
| Input-Output 
| 35
|-
| Input-Output
| 15
| Inst & Exec Cycle
| 15
|}

The balance of the ''Upper console'' was the same on both models:

* Operation Register{{snd}} 25 lamps
* Memory Buffer Register{{snd}} 30 lamps
* Memory Address Register{{snd}} 25 lamps
* Memory Address Register Display Selector – Rotary switch, 12 positions

===Lower console===
* Emergency Off Pull{{snd}} Pull switch
* Check Condition status lamps/switches{{snd}} 15 lamps & 5 toggle switches
* Program Switches{{snd}} 4 toggle switches
* Console operator lights/switches{{snd}} 13 lights, 1 power switch, and 12 buttons

===Console typewriter===
The ''Model I'' console typewriter was a modified [[IBM Electric typewriter|Model B1]], interfaced by a set of relays, and it typed at only 10 characters per second.

There were a set of instructions that wrote to the typewriter, or read from it.  The general '''RN''' (read numeric) and '''WN''' (write numeric) instructions had assembly language mnemonics that supplied the "device" code in the second address field, and the control code in the low-order digit of the second address field.

* '''WNTY''': '''W'''rite '''N'''umeric '''TY'''pewriter: each memory location contained a 6-bit character in the range of 000000 to 001001; with this instruction, each memory location was rendered as one of the characters "0" through "9".
* '''WATY''': '''W'''rite '''A'''lphanumeric '''TY'''pewriter: each pair of memory locations contained two 6-bit digits that appeared on the typewriter as one of the 64 characters that could appear.  
* '''RNTY''': '''R'''ead '''N'''umeric '''TY'''pewriter: read a numeric value from the typewriter keyboard
* '''RATY''': '''R'''ead '''A'''lphanumeric '''TY'''pewriter: read a character from the keyboard and store as a two-digit alphanumeric character
* '''TBTY''': '''T'''a'''B''' '''TY'''pewriter.  Tabs had to be set manually, so this instruction was rarely used.
* '''RCTY''': '''R'''eturn '''C'''arriage '''TY'''pewriter: Caused the typewriter to do what we now call a CR/LF sequence.

To simplify input and output, there were two instructions:
* '''TNS''': '''T'''ransmit '''N'''umeric '''S'''trip: Converts a two-digit alphanumeric representation of "0" to "9" to a single-digit representation
* '''TNF''': '''T'''ransmit '''N'''umeric '''F'''ill: Converts a single-digit representation of digits to a sequence to two-digit alphanumeric sequence that represented "0" through "9"

The ''Model II'' used a modified [[IBM Selectric typewriter|Selectric]] typewriter, which could type at 15.5&nbsp;cps{{snd}} a 55% improvement.