I would love to see someone give a "guided tour" though all the parts of the CPU, and step through some assembly to see how the things works.
I can see from the picture there are distinct areas, and large arrays of gates that might be memory or adders or I don;t know. It would be amazing to see an add interaction actually wire up some memory to some gate and see the result propagate through the CPU.
EDIT: The Art of Electronics has an accompanying book called the Student Manual, which will walk you through the process of (eventually) building a small computer.
> Credit goes to ... Lee Smith for spotting the variable record format used to encode the file (an artifact of the VMS on Acorn's VAX that at first appeared to be widespread corruption of the file),
These days, thanks to Unix and C I suppose, a file is just a collection of bytes. That wasn't always the case. Consider Pascal, where a file is a file of something (records, integers, etc).
So, on VMS, you had streaming files (just a collection of bytes) but also RMS -- Record Management System -- files, which were files of records. There were fixed length records (the record size was probably stored in the file metadata) and variable size records (record size was stored inline, as a byte or word prefix before the record). You might think you're just writing data to a file, but you're writing records (the OS adds the prefix for variable records or 0-pads for fixed length). Then when reading, you might request xx bytes but it will only read one record at a time. (Kind of like how fgets() will stop reading when it finds a newline or a tcp socket will stop reading when it finds a PUSH.)
There are advantages and disadvantages to this but if you're dealing with a VMS RMS file, you need to be aware or it will look corrupted.
Maybe it's simulating an entire OS run - if I leave it on for a few years it will finish zeroing the RAM and start booting :)
For those who would like a bit more detail about the feature of this CPU: http://everything2.com/title/ARM1
One thing I was curious to know is whether the ARM1 had a hardware multiply instruction, whether they could fit that in this tiny CPU. It does not.
There’s a block diagram for the ARM2 in this document: http://www.riscos.com/support/developers/asm/cpu.html I believe the ARM was much the same, with the exception of fewer banked registers & no integer multiplier, so the dedicated could probably trace the paths and make some guesses about where each block is located.
I know it seems like the state-machines of VIC-II are fully documented, but perhaps there could be even more tricks undiscovered?
