DEC Opcodes1.9 - App Store

Dec Opcodes - DEC Architecture Reference

Before the microprocessor, there was DEC. The minicomputers built by Digital Equipment Corporation didn't just advance computing - they defined it. Unix was born on a PDP-7. Spacewar! ran on a PDP-1. The field of Artificial Intelligence was born on the PDP-10. The VAX powered universities and research labs worldwide for a generation.

DecOpcodes puts the complete instruction sets of these legendary machines in your pocket.

Five iconic architectures covered: PDP-1 (1960) . PDP-8 (1965) . PDP-10 (1966) . PDP-11 (1970) . VAX (1977)

For every instruction:

. Full description of what the instruction does
. Octal and hex encoding
. Flags affected
. Addressing modes, word count, and cycle counts
. Assembly code examples and implementation notes

But there is a lot more than just dry opcodes:

. Complete system specifications and register architecture
. Historical context and cultural impact
. Archival photographs - front panels, system cabinets, and more
. Notable installations and the systems they powered
. Architecture variants and successors
. Interactive lessons on assembly language and console operations (ideal if you have an PiDP emulator)

Built for exploration:

. Search across all systems instantly
. A simple assembler for PDP-1, -8 and -11 code
. Filter by instruction category
. Sort alphabetically or by category
. Favorite instructions for quick reference

Beautifully designed:

. System-specific accent colours
. Five themes including Terminal green and Blinkenlights orange
. Full Dark Mode support

From the 18-bit simplicity of the PDP-1 to the 32-bit sophistication of the VAX, DecOpcodes is a fascinating and interactive journey through the machines that made modern computing possible.

All features are free and unlocked. If you like the app you can always leave a nice review or tip the developer!

Version History What's New in v1.9

• DEC Glossary - Searchable guide to 45+ terms across buses, memory, storage, I/O, processors, software, and DEC culture
• PDP-11 instructions added - MFPI, MFPD, MTPI, MTPD (previous-space memory access) and SPL (set priority level)
• Memory Maps corrected - Separate PDP-11/45 (256KB) and PDP-11/70 (4MB) layouts; KW11-L and KW11-P clocks added to I/O page; byte units for PDP-11 and VAX
• Official DEC handbooks linked - Architecture Handbook PDFs from bitsavers for all five systems in Programming Resources
• System landing page setting - Choose whether tapping a system opens the instruction list or the system info page
• PiDP-8 Quick Start expanded - OS/8 first commands, paper tape bootstrap sequence, Spacewar! controls, TSS/8 multi-user login, USB storage guide
• PDP-1 toggle programs fixed - Correct memory addresses and proper ADD-based counting loop
• Dynamic Type support - All sidebar and card text now scales with your preferred font size
• Accessibility improved - Better VoiceOver labels and touch targets throughout
• Faster launch - Removed artificial splash screen delay 1.9 Jul 10 Hello DEC fans! In this update, I added a Glossary, so you can stop dropping DEC-terms into casual conversation. I also updated the PiDP-1 and PiDP-8 sections with some more useful little facts and tips. 1.8 May 26 PDP-11 lessons, and a lot of PiDP simulation hardware help! 1.7 Apr 28 Thanks for your support! This update includes:

• New lessons on programming the PDP-11 in assembly language
• More historical documents and photos
• A list of real world locations to see real PDP computers 1.6 Apr 14 Improved the PDP-1 lessons, and added new PDP-8 lesson. Highlighted notes for users of the PiDP-1 and PiDP-8.
Soon you'll be ready to apply for that engineering job you always wanted (in 1960). 1.5 Apr 6 Added a PDP-1 programming course! Handy if you have a PiDP-1! 1.4 Mar 26 Improved PDP-1 mnemonics.
Added memory maps for computer systems.
Missing PDP-10 instructions added. A lot of them. 1.3 Mar 19 Updated PDP-1 mnemonics for IOT and PDP-1D.
Fixed crashing bug when running app on an Apple Silicon Mac. 1.2 Mar 19 * Corrected some opcode details. 
* Updated the example code windows - with PDP-1, PDP-8 and PDP-11 you can copy the example code over to the Scratchpad where it's sort-of assembled. You can tap on an instruction in the Scratchpad for more information. 1.1 Mar 18 1.0 Mar 13