On 2/11/2012 2:29 AM, Baltissen, GJPAA (Ruud) wrote: > Hallo Jim, > > >> But, I was afraid such constant cycling of the MOTOR line >> with a datasette present might cause it's own issues. > - The older CBMs have two cassette ports with each their own motor line, > so no problem here. > - How many people use still their cassette recorder (CR)? Unplugging the > RTC for those rare moments they use it shouldn't be a problem, IMHO. I would tend to agree, but I am trying to be as compatible as possible. > - But for those people which use it regurlary, make a RTC with an edge > connector to plug the CR in and add a switch to disable the motor line > for the time you don't need the CR. Disadvantage: more expensive. Well, if I use WRITE and SENSE, I don't need the switch (except on 264 series). Yes, I have a passthrough, but it's a passive passthrough, I simply pass WRITE to the RTC SCK line, and hooked SDA to the SENSE line. > - Even a step further: make a pcb for inside the C=. First advantage: > you can directly tap the motor signal at TTL level. And. if needed, let > the owner add a switch to disable the motor line. This can be done by > desoldering one pin of the transistor and wire the pin and the hole to a > switch. Advantages: even less expensive (no connector(s) needed) and no > removal needed during transport. One can even use a bigger (rechargeble) > battery. :-) If I went to all of the trouble to do something inside, there are SO many other and better options for hooking this thing into the memory map. I know I'm mentioning this to the wrong crowd, but the majority of people who still own these units would rather do anything than open up their 30+ year old machine. Full disclosure: Many products require a source of 5VDC from the machine, and the cassette port is an ideal location. Such pigtails requires a small PCB to create the passthrough portion. When I initially designed the cassette passthrough PCB, it bothered me that it was mainly a waste of PCB space. So, extended it just a tiny bit, mainly to make it easier to grab onto for removal, and added a DIP14 footprint matching a ATTINY24/44/84 uC, a simple voltage divider for the motor line, and some jumpers for READ/WRITE/SENSE. I didn't have any expectations for use, but it seemed better than leaving the PCB plain. Now, I need to make a new order, and thought I might add an RTC, because it's a simpler idea (no uC programming needed, just install an RTC and write some 6502 code). It's a through-hole design, and parts can be sourced easily, so I thought it would make a neat DIY project. Anyway, that's why it's external. Jim > > -- Jim Brain email@example.com www.jbrain.com Message was sent through the cbm-hackers mailing listReceived on 2012-02-11 18:00:03
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