Commodore plus/4 + JiffyDOS + SD2IEC

I wanted a modern storeage for my favourite plus/4 a long time ago where I can store a lot of stuff on some kind of flash based solution. Based on a topic on plus/4 World I've decided to get an SD2IEC.

The chosen device runs SD2IEC firmware with a look matching the 264 series (black color, 264-er sticker, powered from the tape port of the 264 series). The guy who makes it can be contacted directly from that topic. He is very helpful (for example I asked for the possibility of flashing the firmware directly from the SD card - this is disabled by default - and he made a custom firmware for me and sent it in e-mail along with the schematic and the manual. I also got the manual in printed form with the device too).

SD2IEC supports JiffyDOS protocol which speeds up the standard serial bus operations a lot. Fortunately it is also available for the plus/4-re from Jim Brain's store.

I got everything and tried it out: it does not work. JiffyDOS works more or lessz (at least the computer starts up) but my only device supporting JiffyDOS is the SD2IEC and it does not work. After several hours of trying this and that I took out a C116 and tried that: the device works. :O

In the end I came to the conclusion (and TLC confirmed that it's possible) that I soldered LEDs on the serial bus lines about 20 years ago to see their state (it was handful for debugging serial I/O) and it corrupts the timings.

Yesterday I tried: desoldered the LEDs from the bus: everything works perfectly. It loads quickly with JiffyDOS (I just have to make sure that I remove the .PRG extensions when saving to the SD card). The JiffyDOS is a bit strange becaue the LOAD command defaults to drive number 10 (that's the SD2IEC) - the first device on the bus but DLOAD tries to use drive number 8 resulting in ?DEVICE NOT PRESENT ERRORs. But DIRECTORY defaults to 10 too. It's strange but I can get used to it. The thing causing some pain is the fact that JiffyDOS turns off the screen while loading. :( Okay, it's understandable becaue on plus/4 (I mean the whole 264 series) you can get stable clock only two ways: by turning off the screen to eliminate TED badlines you will get stable double clock or switching to fixed single clock using TED's $FF13 register but that is half the speed of course.

I have had similar problems with this macine earlier. I've tested Krill's cool loader and it always lost the connection when using a 1571 drive until Krill slowed down the timings a bit.

And I have had the same problem with IEC-ATA too. Probably it's working now?

Now I'm glad as everything just works fine. The only thing left is to make my own loader to work with the SD2IEC (in KERNAL fallback mode). :)