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PicoCPC
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[[Rodrik Studio ]] announced its PicoCPC expansion card, which was is created with the help of [[FreddyV ]] (the author of the [https://github.com/FreddyVRetro/ISA-PicoMEM PicoMEM ISA card for IBM PC]).
[[File:PicoCPC proto2proto.jpegjpg|600px]] [[File:Modular PicoCPC.jpg|600px]]
<br> == Architecture == The PicoCPC use a Pico2, connected via multiplexor. This let enough pin to add an I2S DAC, MicroSD and some more control signals. The Final PicoCPC board will be really different, with soldered RP2350BDirectly soldered. No 5V pin go to the pico. We use some 1 buffer, 1 level shifter, 3 multiplexers. We write to the CPC with 3.3V, we use 5V to the CPC only to drive some signal like A15 for C3 memory mode and IOReq to disable intern floppy. We prefer to have somerthing between the Pico and the CPC, as even if 5V work now, there is no guarantee that the boards will work after some years of intensive usage.It is really better to be carefull.
The board can decode any I/O port and of course RAM/ROM cycles. As it use a Pico2, its RAM is doubled vs Pico1 and it can access a 8MB PSRAM as well.
There is no external ROM, so the microntroller access the emulated RAM/ROM and USB/MicroUSB MicroSD at the same time: Direct write from the uSD to the CPC emulated RAM at 3MB/s (For example).
The PicoCPC is clocked at 375Mhz [https://www.cpcwiki.eu/forum/amstrad-cpc-hardware/picocpc/msg248409/#msg248409 Source]366Mhz. So it is not as powerful as the [[RSF3]] clocked at 480Mhz. But it is more powerful than the [[M4 Board]] clocked at 168Mhz. [https://www.spinpoint.org/2015/10/23/cortex-m4-board/ Source] <br> === Multiplexers === The "Secret" of the PicoMEM/PicoCPC is its multiplexers. [https://www.cpcwiki.eu/forum/amstrad-cpc-hardware/picocpc/msg249997/#msg249997 Source]It allow to limint the number of I/O needed and act as a Voltage converter at the same time. The Pi Pico allow to have multiple PIO core, plus the main core working together in parallel,so the PIO manage the Multiplexer, reconstruct the Address, while CPU core detect and manage the Control signals, Read in advance the High part of the address to jupt to the correct code.(IO MEM Read or Write, Bank number)So, when the Main core is in the correct code section, it can read directly the full Address from the PIO. The PicoCPC use only 12 I/O to manage all the address, Data and Control signals. We can add 2 pin only to control the multiplexer.Then, the CPC bus is "manipulated" Via ROMDIS, RAMDIS, RD, A15, IOREQ (Pico Output) With this way to do, it is possible to be almost as fast with multiplexing that without.
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* Reset button
C3 mode to arrive in the next hardware release(update 09/04/2025: C3 mode works perfectly fine). And much more for the final hardware release: vocal synthesizer, cpr cartridges, usbmouse, wifi, nfc, ...
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== News ==
It’s still far from being finished, but it’s progressing well. What’s still missing: *"Elle est encore loin d'être terminéeLoading and unloading ROMs from BASIC *Copying files between SD and floppy disk *Saving files to SD (for now, the Pico can only read and launch) *Formatting floppy disks *Displays on the I2C screen during the Wizard *All the sound part *All the Wi-Fi part *All the NFC part Prototype 2 will require a major change on the I/O side but should normally open up more possibilities, like the C3 memory mode on 464/664, switching to 512KB of extended memory, and sound. At the moment, I’m aiming for June as a tentative date. Even if the code isn’t finished, mais avance bienthe hardware should be."
*"le prototype 2 va nécessiter un gros changement coté When it works on all CPCs, including the Plus models, and the hardware is more or less final, I’m aiming for June."*"The features will evolve; I/O mais ouvrira normalement plus de possibilités comme le mode mémoire C3 sur 464/664wrote that in the description. The next big thing will be sound—voice synthesizer—but also a second AY chip and maybe some other quirky stuff like Adlib. Then Wi-Fi and NFC."*"I plan to add Wi-Fi later if possible, le passage à 512ko de mémoire étendue et le sonand also USB, which is simpler than micro SD for transferring things."*"I can even say it’s very likely that Plus cartridges will be emulated soon."*"Wi-Fi is planned for the longer term; the separate Wi-Fi module for Pico2 isn’t available yet."*"There are too many boards, often too expensive, hard to find, and with different features. The idea is that the PicoCPC should cost half the price of a DDI5."*"I didn't check the price of DDI-5, but this one will be around 70€."*"I will have a distributor in UK, so no problem."*"When the board is ready, I will open-source both ROMs, the PicoCPC and the Wizard."*"It’s coming along, but it’ll take a few more months. The final board will be pretty high-tech with 4 layers, etc., and some surprises like connectivity features."*"There will be a case around it to make it look like a peripheral from back in the day."*"The HDD part isn’t great; binaries that load other binaries won’t work. In the end, I could only put a few games on it."
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== Links ==
* [https://youtu.be/jfOszwaVW7w PicoCPC project presentation - 16/01/2025]
* [https://youtu.be/ysX8sibAoNk PicoCPC project update - 07/03/2025]