While looking for other possible uses for the 3d-printed modified molex
carrier and matching pcb, I discovered the Epson PX-8, which has a z80
and runs cp/m, so, I would guess that means there is even already at
least some sort of body of code to use cp/m on a device like this. I
guess that doesn't actually mean much besides "expects a screen this
small" because all the actual hardware must be completely different. But
then again, you will already be having to make cp/m deal with the
hardware, so maybe existing software won't be so far off from working
after all.
The fact that the resulting machine will run cp/m (or any generic os)
definitely saves this idea from being interesting but inexplicable. It's
awesome.
...and please forgive me going off on a tangent now... that just made me
think of the opposite direction, instead of a generic os like cp/m, a
Model I/III mode. "Model 1 on a stick!"
No good answer for the screen though. Just not enough pixels to get
64x16 characters even with the "Tom Thumb" 3x6 font, so it would need a
screen hanging off the printer, serial, or bus ports.
Then again, a Model 1 mode could maybe work with a DVI.
Except then you have to live with the character generator in the dvi and
couldn't fully replicate the model 1 character set. Mostly no problem
since the m1 has fewer characters and mostly just the basics, but the
block graphics are different. M1 has glyphs made of 6 squares per cell.
DVI has ones made of 4 squares. But hmm, dvi has 80x25 cells, M1 has
only 64x16... so dvi has more total "pixels" at 160x50 than M1 at
128x48, so you could map a purely graphics M1 image onto a dvi. Where
text and graphics are mixed, no good answer, just have to pick a closest
matching glyph by overall appearance.
Then again... given a generic os like cp/m, maybe it can simply run a
model 1 emulator as an application. Especially since this one would have
5 to 8 mhz to work with, to emulate a machine that only ran at 1.8 mhz.
--
bkw
On 7/11/19 10:30 AM, Stephen Adolph wrote:
Motivated by 2 things
1) discovery of the NSC800 Z80 processor that is 80C85 like
2) continuing to work in the direcition of CP/M
3) and recalling that there are 5MHz 80C85 parts out there..
I started to work on a dual CPU card for M100 that enables a couple of
things;
- standard 2.5MHz 80C85 operation (default)
- switchable clock for 80C85, supporting 5MHz
- switchable CPU enabling NSC800 at 2.5 MHz.
Board is done and heading to the fab. VHDL is mostly done.
I don't expect this board will be wildly popular but maybe it has some
interest Double speed M100 seems interesting on it's own, let alone
being able to support Z80 CP/M applications.
Any interest?
I have purchased material to make 5 of these.
A few more comments.
- to install this board you need to remove the 80C85. that's some
effort to do
- to run at 5MHz you need to upgrade the 81C55 to a 5MHz version.
That's also some effort.
- NSC800 runs about 5$ on ebay.
- fast 80C85 can be had for under 5$.
- fast 81C55 can be had for under 5$.
- to run at 5MHz you might also find you need a faster main ROM, and
faster RAM. TBD on that; will advise after I do some testing.
