BKW - is it worth it? Haha - that's an interesting thought process right
there. This is what I do to entertain myself so value of time and parts is
subjective. I'm gonna buy ten times the needed parts, build several
revisions of something and proudly display them all!
If we are gonna go explore "is it worth it" I think it's important to look
at one of the reasons why getting our hands on a NDP was so difficult to
begin with. What exactly are we going todo with them once we have them?
That's a question for Future Brian though, not me since Current Brian
doesn't yet have one.
I like the practical approach of adding U8 to your design. Woz would
approve. In the world of solving problems that no one has by creating
features no one needs I do wonder how this is going to perform when data
needs to span both banks or needs to be copied from one bank to another.
More of a playing with it than an actual situation that needs to be
addressed.
Don't know if you play with any of the Epson hardware or not but I recently
got my hands on an Epson PX-8 128K "smart memory" expansion board. It's got
a whole Z80 in it that acts as the MMU. The system can then treat it as
just an I/O addressable device and it handles everything else. But what do
you get for a computer that has 3 processors already? Another processor for
memory!
The C64 had the GEORAM 512K memory expander and they use to make two
registers in the upper memory address space to expand the address space
available to the 6510. If you read from those address spaces on the
computer they would return random values but when the decode logic did it's
thing it would pull index from those two memory spaces.
Just neat stuff all the way around, but what you were talking about
recently has me curious, we should be able to access known memory locations
on the MiniNDP with some ML calls in basic pretty easily. Then be able to
bootstrap RAM.COM. I saw Paul G. write a few things about it and even make
reference to the idea that read-rom (or whatever the .co was) could be
loaded with some modification.. We should be able to send an I/O READ
command and peek at the address location we want. This seems like a fun
thing to play with.
But thanks for making a NDP I didn't have to pay tons for and fits in my
pocket!
Brian
On Wed, Dec 13, 2023 at 5:55 PM Brian K. White <b.kenyo...@gmail.com> wrote:
> Is it worth trying to come up with some surgery bodge procedure to
> upgrade a 256K unit to 512?
>
> It's a very small change and although there is an added part and it's
> tiny and not easy to solder wires to, it's probably actually possible to
> cut a few traces and add the new part with fine wire-wrap wire and glue
> it all down.
>
> I think the new part (LVC1G79) can even be soldered to the board pretty
> much right where it is on the new board instead of dead-bug, because two
> of the pins are VBUS & GND, and they are on opposite corners of the
> package, and both are available on the pcb in the right spots already
> just by scratching the soldermask pretty much right where the part goes
> on the now board. Angled a little but hey whatever. So that not only
> connects 2 of the 5 pins, it mounts the part as if there were a footprint.
>
> Two more pins have short easy bodge wire runs to nearby exposed pins
> with no need to cut any traces or anything. Those are /BLOCK and
> BUS_A10. Pin 1 goes over to connector pin 16 and pin 2 goes over to U4
> pin 14. Just add the wires to existing exposed legs, no cutting traces
> or lifting legs.
>
> That just leaves pin 4 A18, which needs a trace cut on the back side of
> the board, and a wire run from pin 4 to sram pin 6. The trace to cut is
> the one that ends with a via right in the D in NODE on the back side,
> it's a thin trace that runs down towards the connector, and transitions
> to a fat trace before going under the connector. Break the thin section,
> do not break the fat section.
>
> And actually since we're not soldering to a footprint, you can buy a
> larger package version of the part so the lags are a easy to solder
> wires to. It's available in SOT-23-5/SOT-753/SC-74A which should be dead
> easy.
>
> Ok well I guess I just did the thing I was asking if it was worth doing.
>
>
> But, it's probably not much worse or maybe even easier to just
> transplant all the parts from a built 256k to a new 512k board. That's
> what I did. I didn't bother with the caps or resistors but all the chips
> I desoldered with chipquick, cleaned the low-melt off with wick, and
> soldered to the new board.
>
> In one sense it's silly to spend that much time on parts that add up to
> a couple bucks, your time is worth more, but on the other hand if you
> didn't buy 100 of each part and you've built a few along the way
> developing... it's hard to look at a board full of parts and just toss
> it rather than scavenge the parts. The math does not justify it at all
> since I'm not broke, plus the chipquick and kimwipes and flux-off isn't
> free, but I just can not make myself not scavenge those parts!
>
> My REX Classic is on revision 30 or so by now, and I have 3 or 4 rexs
> that have had their chips transplanted like 10 times, and so far
> everything has seemed to survive all that accumulated solder hot time
> and ultrasonic cleaner time. Everything is still working anyway.
>
> --
> bkw
>
>
> On 12/13/23 16:34, Brian Brindle wrote:
> > Haha - Glad you like it Joshua if I do happen to make more or improve on
> > this one I'll let you know. I don't exactly have ADD but what I do seem
> > to have is the inability to control what my current interests are and
> > recently it's been playing with CP/M on the M100, PX-8 and building up a
> > CP/M emulation environment on the TanPi. That was going great till I
> > managed to get my hands on one of the MiniNDPs Brian K White made and
> > now I'm all about his recent 512K upgrade. Never thought I'd get to play
> > with an NDP so this is exciting stuff.
> >
> > I have a WP-2 and have tried to use the TanPi on it, but usually ended
> > up frustrated with the lack of needed keys. When doing unixy stuff
> > having pipes, curly braces, back ticks etc are handy. The M100 seems to
> > have everything I need, although you do have to know to hit shift GRPH -
> > to do a pipe and GRPH ( for { etc.
> >
> > I like ROM-View 80 but for me it's not enough of a payoff to have to
> > reconfigure the local terminal settings to accommodate the new layout.
> > The way I use the TanPi is primarily for content creation and syncing. I
> > will write documents either with a real editor or just by typing cat >
> > file.txt and typing away with CTRL-C to stop. Then sync the files with
> > my local storage or the cloud when I have WiFi. If I need to do
> > something really heavy I'll use an external screen or my VNC session
> > with my phone.
> >
> > A lot of times when I'm at home I will ssh into my TanPi from my desktop
> > and can drag/drop files over SSH, use the real keyboard and monitor for
> > stuff and it's quite handy.
> >
> > It's a fun toy.
> >
> > Brian
> >
> >
> >
> > On Wed, Dec 13, 2023 at 1:29 PM Joshua O'Keefe <maj...@nachomountain.com
> > <mailto:maj...@nachomountain.com>> wrote:
> >
> > > On Dec 13, 2023, at 6:22 AM, Brian Brindle <bbrin...@gmail.com
> > <mailto:bbrin...@gmail.com>> wrote:
> > > My whole setup is a total kludge / hack that I never expected to
> > use long term. I was just doing a POC and built the whole thing in
> > about 10 minutes with stuff I had laying around but here we are
> > almost five years later...
> >
> > Brian, you may consider this rig a kludge, but I'm jealous and think
> > it's gorgeous. Using the T as a portable terminal with a perfectly
> > capable tiny Linux box cleverly attached is a great hack. I wish I
> > had one of these! A 9-pin WP-2 version—what with the 80-column
> > display—would be amazing.
> >
> > Now that I think about it, have you tried using either one of the
> > 80-column software setups, like ROM-View 80 or Ultrascreen100? It
> > might make for an even more pleasant terminal experience.
> >
> > Gosh, I'm tempted to ask if you'd slap another one together in your
> > copious free time!
> >
>
> --
> bkw
>
>
