New microdrive internal replacement

[Peter]

But: You simply can't implement some very "clever" stuff like the ZX Spectrum's "floating bus" or the ZX81 video circuitry with a 68008, at least not that I would know.

Funny, you just reminded me that the QIMSI interface actually implements a 68008 "floating bus". QIMSI and QL buses are kept separate by 470 ohm resistors on each data line. This is enough to allow the data lines to be properly driven by devices on each side of the bus without causing any outputs to be shorted low or high if driven at the same time. This allowed me to optionally have QL-SD plugged in and its "microdrive" card slots used by QIMSI. (Well not as clever as some of the ZX Spectrum wizardry, but still.)

Another effect is that this choice of resistors between the busses nicely re-shapes the FPGA signals for slower rise and fall times on the QL side, avoiding the crosstalk and ringing caused by "too fast" logic on the QL mainboard, e.g. seen with (S)GC.

[Popopo]

I hoped to be able to count to three The RP2040 development board, the board for the MDV area and the external board.

Oh, then should be count to 6, the mSD modue, the screen module and voltage regulator too. In fact, maybe some level-shifter also should be count as board.

Indeed, I find the QL mainboard not very clever and Sinclair style, compared to the ingenious Spectrum design. But for different reasons.
I wasn't advocating FPGA for microdrive emu. It is amazing what can be done with the cheap RP2040.
Side note: FPGA logic implements hardware, just as a PLD, there is no emulation as many think.

Side note: FPGA is a hardware emulator since it is not same than original. But... playing words and POVs.

Allow an internal solution, have a more compact board despite a larger card socket, a single board instead of three, and save costs for a machine soldered batch.
I was just sending feedback what I would like & buy. If you prefer the way it is right now, fine. It's a hobby after all, have fun! Nice video by the way!

Thank you

Of course not. E.g. think about using C68, SMSQ/E, many files open in parallel, long files...

No idea, I have not any of those solutions.
But ... perhaps this file limitation not need to be in this solution. Does it?

[Popopo]

You just need to add audio functionality now, so it sounds like a Microdrive.

I have a circuit for that. Hehe. (It's just an ATTiny85 which plays an audio sample whenever it's energised. On the vDrive I used the activity LED.)

Hi again
The new versions boards are today in final test (in some hours I'll check if they work).

Could you show me how you could add this "noise" to emulate original one?
I imagine how it is, since I have seen it in other projects. But, I could do a new version adding the footprint and lines to add it as option for everyone who would love it as close as original (With noise included).

If it is optional and there is the space, I could try it out.
Just ... perhaps could be even better you do it in your board and if it works and not introduce noise in other lines, then add it.
What do you think?

[stephen_usher]

All you need is an ATTiny85 and a way to switch its power on and off using an output from the Pico. In the case of the vDrive I used the activity LED power to switch a transistor. The speaker is directly connected to two of the pins on the ATTiny85.

[tofro]

Side note: FPGA is a hardware emulator since it is not same than original. But... playing words and POVs.

Just as much as a "NEC Z80" is a "hardware emulator" of a "Zilog Z80" because it's not the same than original?

[stephen_usher]

Side note: FPGA is a hardware emulator since it is not same than original. But... playing words and POVs.

Just as much as a "NEC Z80" is a "hardware emulator" of a "Zilog Z80" because it's not the same than original?

Well, if it were a "software defined processor" or used microcode to run the Z80 instructions on the ALU then it would sort of be. If it's merely a different hardware mask then not. No doubt Zilog changed the masks sometime during the production period as the IC technology changed and shrank.

[tofro]

Iwas actually not trying to start a discussion. This was rather meant as an trigger on how useless such a discussion would be

[Popopo]

All you need is an ATTiny85 and a way to switch its power on and off using an output from the Pico. In the case of the vDrive I used the activity LED power to switch a transistor. The speaker is directly connected to two of the pins on the ATTiny85.

Hum...
not so simple as I thought.
I think, Noel Llopis did something similar in the place of a LED, need to check it out.
Don't know... how much cost the ATTiny and other components... but remember, I have not vDrive.
So any solution must be independent of 3rd parties solutions

[Popopo]

Side note: FPGA is a hardware emulator since it is not same than original. But... playing words and POVs.

Just as much as a "NEC Z80" is a "hardware emulator" of a "Zilog Z80" because it's not the same than original?

Whatever your color is.
FPGAs solutions to synthesizes another IC is a emulation.
If it were exact as original, not revisions were needed.
Even if, in laboratory conditions it works, you cannot affirm that in other environment the behavior will be the same.
But... if you... YOU, synthesis a circuit same than it was in the fab... OK. Deal now with form factors, voltages levels, speeds, temps ranges, humity... etc etc... if you get the same and certify it... congrats.
I use FPGAs "almost" same than others solutions. FPGA is what it is and It is depending on its purpose.

Note: NEC version is ... that, a version from their own implementation from a FAB. Same than Cyrix86 is to Intel.
And please, that is not the place for such subjects.

[Popopo]

And all tests passed

So time to offer part of it to who want to try it out.
At any case... about the cost is something like...

Counting to buy materials by lots.

So... soon will opened a thread now for who want a board PCB or a mounted and tested version.
PLEASE!!!
READ the original document BEFORE request a kit.

I am not a shop, and I am not doing business so keep it in mind.
don't want misunderstanding