M-1114 MulDivIns Jun61

This document consists of two parts, indicated by different memorandum numbers:

Part 1: Permanent Memorandum M-1114 (Page 1 of 5)

• Date: June 29, 1961
• From: Ben Gurley
• To: PDP Distribution List
• Subject: Specifications for the Multiply and Divide Instructions in the Type 10 Multiply/Divide Option.

The memorandum details two instructions:

1. Multiply (MUL Y, Operation Code 54):

   • Execution Time: 14 to 25 microseconds.
   • Function: Multiplies the contents of the Accumulator (AC) and the Y register.
   • Result: The product is stored in the AC and IO registers. The product's sign is found in AC0 and IO17. The 34-bit magnitude is in AC1 through IO16.
   • Unaffected: The contents of the Y register (C(Y)).

2. Divide (DIV Y, Operation Code 56):

   • Execution Time: 30 to 40 microseconds (or 12 microseconds if an overflow occurs).
   • Inputs: The dividend is expected in the AC and IO registers (IO17 is ignored). The divisor is the contents of the Y register (C(Y)).
   • Result: Upon completion, the AC holds the quotient, and the IO register holds the remainder. The remainder's sign matches the dividend's sign.
   • Overflow Handling: If an overflow occurs, the division does not take place. The AC and IO registers remain unchanged, and an overflow indicator is set.
   • Unaffected: The contents of the Y register (C(Y)).

Part 2: M-1116 (Pages 2-5 of 5) These pages list various components by "Type" (likely part numbers or model identifiers) and their corresponding "Quantity." The lists are categorized by different system modules or functions, including:

• Central Processor
• 4096 Word Memory Module
• Reader, Punch, Typewriter
• Multiply & Divide Type 10
• Sequence Break System Type 20
• Jump Field Type 14
• High Speed Channel Control
• Tape Control Types 52, 50, and 51
• 32-Channel Sequence Break System