Beech (BBC Micro Emulator ) 0.5

Some major fixes to the sound output.

• ENVELOPE decay and SOUND volumes use a 2dB step instead of a linear ramp, matching the real SN76489 chip.
• Music 500/5000 should be much improved*, thanks to a discussion on stardot.org.uk which hoglet messaged me about literally years ago. Thanks for that and sorry for the extremely long wait until I dealt with it.

Usage, requirements, and other info at the original post: https://darrenizzard.com/index.php/2015/08/24/beech-a-bbc-micro-emulator/

* I’m aware that the Music 500/5000 output is still missing the four-pole filter at the output stage. My reading of the schematic doesn’t match how recordings sound, and while I know the b-em emulator has two filters built-in, I didn’t want to reuse those coefficients without knowing where they came from (or indeed without permission!).

I don’t have a real device to check but if anyone could send me a good-quality photo of the board, it’d be much appreciated. The bits I’d like to see is are the four capacitors around each TL072, clear enough to read their markings. That’s C21-C24 on the right channel, C15-C18 on the left. Also the issue number silk-screened on the PCB.