16-03-2024, 10:44 PM
Time for another update.
Large changes have been made in regards to the second processor.
I had planned to have an M68k softcore processor as the second process to handle the SDcard floppy disk emulation
be able to run in M68K mode for CP/M68K etc.
On evaluation, the performance of the core once timing had been met for the FPGA design was not as good as I was wanting.
So, to plan B :
As part of the design of the new SODimm module with the Lattice FPGA, I also included the option of loading a MC68SZ328 Dragonball
processor which can run up to 66Mhz, and so, I've committed to using this as the second processor.
I had some teething problems getting this going though - it would run some code & then go off it's tree. It turned out, after a couple of
weeks of debug, that I had swapped 2 data pins (D14 & D15) on the pinout of the processor. Once this was found and fixed, code started
running nicely.
I now have the Dragonball running simple boot code located in block ram in the FPGA. That Boot code initializes the chip selects and
memory regions for the onboard memories, then loads run time boot code (for the floppy emulation, Boot file manager, OS etc.) from the FPGA
configuration flash (convenient place to store the M68K boot code).
Additionally, it loads the Z80 boot rom image from the configuration flash and programs the 'Boot RAM' (normally the Microbee
boot rom) on the main board before handing control to the Z80 (in the case of booting into Z80 mode).
I designed the board to have RAM in place of the normal Boot ROM so that you can optionally load different boot Roms in place of the
standard included boot rom image. For example, if you wanted to load a standard BN56 ROM image instead, you can do that, or
perhaps even boot straight tape basic loaded in place of the normal boot rom.
Another major decision has been made as well.
The name of the Classic Plus, and the [256] TC Plus will be changing prior to release.
On reflection regarding these names, it makes the models sound like they are normal Premium series machines
with a few extra bits tacked on, which in reality is far from the case.
There is so much more to these new models than these names suggest, and more even that I am yet to
release details on, so they deserve to be known as new models in their own right.
There will be a launch day and the new names will be revealed at that time.
That day is getting closer.
I thought I would also mention about the long development time on this project, and while there has been quite a number
of setbacks in the design phase, there has also been other things holding it back.
In rebuilding the brand I have had to make sure there is diversification of income streams, and not just rely on one (retro-computing).
Additionally to traditional Microbee product offerings, there are 2 other areas that Microbee relies on and that is Design services (from
concept to prototype, and small production), and Surface Mount & Through hole assembly services. Over the last 6 - 8 years, the SMD
loading part of the business has been something that has been grown significantly and we are now doing 600+ boards a month
through our pick and place machine.
The benefit of this is that with this growth, development of Microbee product is now easier to allocate time to, but it has taken quite
a lot of time and effort to be at this point.
When I look back at the date on the prototype Classic Plus boards (2016) I do get quite disappointed that it has taken this long, and that
there has not been significant Microbee Product releases in all that time, however, I am pleased in the position that Microbee is now in
and poised for further growth this year.
More updates on the new models coming in the next weeks.
As always, thank you all for your continued interest and support.
Large changes have been made in regards to the second processor.
I had planned to have an M68k softcore processor as the second process to handle the SDcard floppy disk emulation
be able to run in M68K mode for CP/M68K etc.
On evaluation, the performance of the core once timing had been met for the FPGA design was not as good as I was wanting.
So, to plan B :
As part of the design of the new SODimm module with the Lattice FPGA, I also included the option of loading a MC68SZ328 Dragonball
processor which can run up to 66Mhz, and so, I've committed to using this as the second processor.
I had some teething problems getting this going though - it would run some code & then go off it's tree. It turned out, after a couple of
weeks of debug, that I had swapped 2 data pins (D14 & D15) on the pinout of the processor. Once this was found and fixed, code started
running nicely.
I now have the Dragonball running simple boot code located in block ram in the FPGA. That Boot code initializes the chip selects and
memory regions for the onboard memories, then loads run time boot code (for the floppy emulation, Boot file manager, OS etc.) from the FPGA
configuration flash (convenient place to store the M68K boot code).
Additionally, it loads the Z80 boot rom image from the configuration flash and programs the 'Boot RAM' (normally the Microbee
boot rom) on the main board before handing control to the Z80 (in the case of booting into Z80 mode).
I designed the board to have RAM in place of the normal Boot ROM so that you can optionally load different boot Roms in place of the
standard included boot rom image. For example, if you wanted to load a standard BN56 ROM image instead, you can do that, or
perhaps even boot straight tape basic loaded in place of the normal boot rom.
Another major decision has been made as well.
The name of the Classic Plus, and the [256] TC Plus will be changing prior to release.
On reflection regarding these names, it makes the models sound like they are normal Premium series machines
with a few extra bits tacked on, which in reality is far from the case.
There is so much more to these new models than these names suggest, and more even that I am yet to
release details on, so they deserve to be known as new models in their own right.
There will be a launch day and the new names will be revealed at that time.
That day is getting closer.
I thought I would also mention about the long development time on this project, and while there has been quite a number
of setbacks in the design phase, there has also been other things holding it back.
In rebuilding the brand I have had to make sure there is diversification of income streams, and not just rely on one (retro-computing).
Additionally to traditional Microbee product offerings, there are 2 other areas that Microbee relies on and that is Design services (from
concept to prototype, and small production), and Surface Mount & Through hole assembly services. Over the last 6 - 8 years, the SMD
loading part of the business has been something that has been grown significantly and we are now doing 600+ boards a month
through our pick and place machine.
The benefit of this is that with this growth, development of Microbee product is now easier to allocate time to, but it has taken quite
a lot of time and effort to be at this point.
When I look back at the date on the prototype Classic Plus boards (2016) I do get quite disappointed that it has taken this long, and that
there has not been significant Microbee Product releases in all that time, however, I am pleased in the position that Microbee is now in
and poised for further growth this year.
More updates on the new models coming in the next weeks.
As always, thank you all for your continued interest and support.