diff options
| -rw-r--r-- | internals.rst | 41 |
1 files changed, 24 insertions, 17 deletions
diff --git a/internals.rst b/internals.rst index f9bfee4..d11dbce 100644 --- a/internals.rst +++ b/internals.rst @@ -38,21 +38,28 @@ only. A few internal registers like instruction counter, condition flag for branching, several segment and status registers and a stack pointer exist. The CISC instruction set was specifically designed for the high-level language -ELAN. It includes arithmetic operations for ELAN’s primitive datatypes such as -signed and unsigned integer as well as float (REAL) and operations for -bytestrings (TEXT) and dataspaces. However the machine itself does not enforce -datatypes at runtime. The usual control flow operations are accompanied by -ELAN-specific call and return instructions. Special instructions for terminal -and archive disk I/O, exception-like error handling and inter-process -communication (IPC) are available. - -The 54 primary instructions can be encoded with two bytes. They consist of a -6 bit opcode and one short operand. Whenever the latter is longer than 10 bit a -long encoding using two bytes plus operands is used. This format also encodes -42 secondary/special instructions. - -Read more instruction encoding details in chapter two of [kernel83]_ and the -ELAN package `eumel coder`_. - -.. _eumel coder: system/eumel-coder/1.8.1/src/eumel%20coder%201.8.1.html +ELAN. +It includes arithmetic operations for ELAN’s primitive datatypes such as signed +and unsigned integer as well as float (REAL) and operations for bytestrings +(TEXT) and dataspaces. +However the machine itself does not tag data and therefore doesn’t enforce +types at runtime. +The usual control flow operations are accompanied by ELAN-specific call and +return instructions. +Special instructions for terminal and archive disk I/O, exception-like error +handling and inter-process communication (IPC) are available. + +Some of the 31 primary instructions can be encoded with just two bytes. +They consist of a 6 bit opcode and one short operand. +Whenever the latter uses more than 10 bit a long encoding consisting of two +bytes opcode plus operands is used. +This format also encodes 127 secondary and six special instructions. + +Details can be found in chapter two of [kernel83]_, the ELAN package `eumel +coder`_, `this debugger’s sources and documentation`__ and a reimplementation +of the EUMEL0 virtual machine, EUMuLator_. + +.. _eumel coder: src/system/eumel-coder/1.8.1/src/eumel%20coder%201.8.1.html +.. _EUMuLator: https://github.com/PromyLOPh/EUMuLator +__ src/devel/debugger/1.8.2/src/DEBUGGER.ELA.html |