After a year of waiting, it’s time for ORCONF. If you are not familiar with ORCONF, then allow me to encourage you to examine their web-page, and look over the abstracts of the presentations that will be given this year. Looks like it will be quite the lineup.
This year, I’ll be giving two presentations.
8-bit byte-level access across the 32-bit bus.
Prior to this redesign, the ZipCPU was one of a few rare 32-bit byte machines.
Now, the ZipCPU fully supports 8-bit bytes instead of the 32-bit bytes it supported before.
This required a bit of instruction set redesign. Opcodes were re-ordered. Rotate left
ROLand population count
POPCinstructions have been removed. The load and store instructions have been renamed load word
LWand store word
SWinstructions. Four basic instructions have been added as well: load half-word
LH, store halfword
SH, load byte
LBand store byte
A compressed instruction set (CIS).
The ZipCPU has always had a CIS, although it was previously mis-named as a Very Long Instruction Word (VLIW) set of instructions–which it never really was. The CIS instruction set allows you to integrate pairs of 16-bit instructions together with the 32-bit instructions. It provides some increased code density as a result.
Nearly the same number of LUTs
Despite all of these changes, the number of LUTs used by the ZipCPU remains roughly the same.
Placing a CPU into a new environment can be a daunting task. Components need to be selected, resources allocated, addresses given, interrupts assigned, and peripherals configured–not only in the HDL code, but also for all of the software support. The problem with this approach to designing hardware is that it works very well for one-off solutions, but not as well for quickly creating generic solutions to new problems. This is where AutoFPGA comes in.
Given a set of components, AutoFPGA builds the boiler plate files, the top level and main design files, the Wishbone interconnect, and the software header files necessary for software support within that design. As a result, I can reconfigure a project with new hardware in a matter of minutes, rather than the days it took before.
When I get back, I’ll post about my experiences and thoughts. When the presentation video’s are posted on youtube, I intend to post those links here as well.
For the kingdom ofheaven is as a man travelling into a far country, who called his own servants, and delivered unto them his goods. (Matt 25:14)