A couple of days ago I received a Plus One from Dave H. Many thanks for this! After opening it up and having a good look at the schematic, I thought it might be possible to hook at 99p MMC interface directly up to the printer port.
The first issue with this is there is no +5V present, but that's easily fixed with a wire: There are several unconnected pins on the printer port (21..26). I chose pin 26 as this is typically connects to an input on the printer. Which means if you want to occasionally connect a printer than nothing bad should happen. If I had a 100mA PPTC resettable fuse to hand then I would have probably included that as well.
The following connections were then used between the Elk and the SD Card interface:
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Electron SD Card 2 GND ===> GND (Black) 3 PD0 ===> MOSI (Grey) 5 PD1 ===> SCLK (White) 10 GND ===> CS (Blue) 19 ACK <=== MISO (Purple) 26 +5V ===> +5V (Red)
https://github.com/hoglet67/MMFS/blob/m ... kPlus1.asm
The only part of this that's really new is the subroutines starting with P1_ that do the bit banging of the clock and data. The rest is pretty much the same as for the user port.
And here it is working: Speedwise, this will be a bit slower than MMFS connected to an EUP, but honestly it's not too bad at all.
If anyone wants to build one, then you need the latest release of MMFS (currently 1.30), and the build you need is in the "E" directory.