"New" SD interface

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jdavis6809
ROM Dongle
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Re: "New" SD interface

Postby jdavis6809 » Mon Dec 02, 2019 11:46 am

hello,

going into production ?

regards

john


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Dave
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Re: "New" SD interface

Postby Dave » Mon Dec 02, 2019 6:16 pm

Another lovely card by Tetroid. :D


Silvester
Trump Card
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Location: UK

Re: "New" SD interface

Postby Silvester » Mon Dec 09, 2019 12:39 pm

I notice that you didn't use a trimmer capacitor with the PCF8583 crystal ?

I built a Minerva Mk2 last year from discrete 74xx logic. Without a trimmer capacitor my PCF8583 clock ran very fast. With QL powered up it was 3 minutes fast per hour!, but only reducing to 20 seconds fast per hour when on battery.

I solved the 3min/hour problem by putting 220pF capacitor across PCF8583 pins 4 & 8 (noisy QL hardware). With a 30pF trimmer between pins 1 & 8 I was able reduce RTC error to less than 1 second a day :-)

I notice from a photo of real Minerva MK2 that they also used a trimmer.

BTW I thought I had a faulty NETwork until I realised if you initialise all RTC ram locations to 0, the NET number gets set to 0 upon each reset (should default to 1). This stops the TK2 network fileserver from working (SuperBASIC NET command disallows setting NET 0, but Minerva MK2 does, oops).


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