About+this+group

The [|Hercules Emulator] : //"//**//Hercules//** //is an open source software implementation of the mainframe System/370 and ESA/390 architectures, in addition to the new 64-bit z/Architecture. Hercules runs under Linux, Windows (98, NT, 2000, and XP), Solaris, FreeBSD, and Mac OS X (10.3 and later)."

This wiki is about programming the Hercules 390 emulator, i.e. a "mainframe" computer, using assembler, and machine language instructions.

"Bare metal", means that no Operating System, will be used. Only the "bare" machine.

The primary focus is on I/O programming, using the channel mechanism, the SIO type instructions for the S/370, and the SSCH instruction for the ESA/390, ESAME. (Hercules can emulate all three types of architectures)

The main reference manuals are the Principles of Operation, for each architecture.

Any other technical subjects related to Hercules / mainframe programming, are welcome

As of this writing ( May 16 / 2010), Hercules supports three distinct architectures :

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 * 1) // S/370 - - [|Principles of Operation (1975)] //
 * 2) ESA/390 [| Principles of Operation]
 * 3) ESAME / zArch  [|Principles of Operation] [|Reference Card]

// The "core" instructions in ESA/390, and ESAME are backward compatible to S/370 //

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The I/O instructions / mechanism is different for S/370 compared to (ESA/390 and ESAME).