Errors in the specification

[TecTrixer]

• The way syscalls work and which codes they use are not specified
• Where do the print syscalls get their value from?
• The hash function is not specified
• Which instruction is being executed first?
• Is memory initialized with 0 by default?
• Which byte corresponds to which register? (00 <-> A, ...)?
• Do load and store work in a little endian or big endian way? If an int from address x is loaded is x+3 the highest or the lowest byte?
• Technically push / pop is not fully specified (does it decrease the stack pointer)?
• The calling convention is defined for a programming language, not for an instruction set, only the way call and ret work should be specified
• How does the parameter mode register address and relative address work? Specifically how many bytes do they take?
• Can the constant parameter modes be used for writable parameters? Is this undefined behaviour, should the cpu panic?
• Push and pop, when do they increase/decrease S?
• better describe how lw works
• does loading into smaller registers overwrite the top bits?
• revise ld register something regarding the size of the operation
• specify how many bytes should be read from memory using absoluteaddressing, relativeaddressing, ...
• when setting the lower bits of R with operations such as inc, will the upper bits get replaced by zero or do they stay untouched
• what happens to R when using the mod instruction
• do the print and println syscalls read the string upwards or downwards?
• what happens with the R register with the floating point operations
• are set, clear, toggle and test 0 or 1 indexed
• what does test do? does it set the i'th bit in r on success or the 0'th bit?
• more explicitly define the random number generator, it is not said anywhere that the top 16 bits are being taken and not the bottom 16 bits

[vypxl]

Please make checkboxes

[TecTrixer]

done

[vypxl]

To the calling convention thing, I think it's reasonable to define a standard way to do things, I added a comment that it is just a convention. A convention just helps with code reusability.

[vypxl]

Please have a look, I updated the spec.

[TecTrixer]

lgtm 👍