Sunday 23 December 2012

Tape loading

So, something I've been meaning to test ever since I designed this board back in March and got them made up in April is the tape input. So here is Rampage running on the emulator and loaded from real tape:

Since the first prototype, I've been pretty busy and not had much chance to work on the emulator and whenever I did get a chance I was stuck because the flash chip on the board didn't seem to work properly. There's a bunch of reason why it might not work - it might be dodgy soldering, although I reworked all the soldering on the FPGA pins and flash chip pins a number of times, and testing it with my scope suggests it should work. It could be the chip itself which is dead (2 of the 3 boards seem to have dead flash) or it could even just be because I forgot pull-up resistors. Reading the datasheet, these don't seem to be required, but who knows...

Anyway, the other day, I knocked up a small daughter board with a flash chip from a different manufacturer and that all seems to work fine, so I'm able to carry on with the testing I could have been doing 6 months ago!

Here's a close up of the board taken with a decent camera rather than my camera phone and also the emulator running 1943 (also loaded from tape):

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