M0UAW's Blog

If you've any interest in reverse engineering old code, Ghidra does a pretty good job of it though it does seem rather massive overkill to run it against <400 bytes of assembler.  I hope nobody objects to this, I've tried and tried to locate schematics and information on this oddball radio but even the people I've managed to track down from Garex/AKD don't seem to have it.   If you own this code and object to my posting it here, please contact me, I *will* remove it but also bear in mind reverse engineering is legal.     This is the code from the AKD: LAB_fc00 XREF[1]: fffe(*) fc00 8e 00 1f LDS #0x1f fc03 86 2d LDAA #0x2d fc05 97 20 STAA DAT_0020 = FFh fc07 86 00 LDAA #0x0 fc09 97 22 STAA DAT_0022 ...

Per previous post, my unusal/1st gen AKD Some notes:   Processor: MC6802 PLL NJ88C30, PLL Reference Oscillator 10MHz, Ref Osc divisor = 400, channel spacing = 25KHz On RX VCO runs at RX Frequency - 1st IF (10.7MHz) TX VCO runs at TX Frequency.  EPROM 27C128 Mapped to $E000-$FFFF (mostly unused, No code before FC00, only 1K used)   It seems to be a very simple design where the various 'peripheral' parts are memory mapped using a 74LS138 3-8 Decoder, it's not fully decoded so any write which addresses A13, A14, A15 or any combination will enable an output on the 'LS138   CP is the clock pulse for the 4024 Binary counter which generates the 1750 Toneburst  CLK is the PLL Clock Latch is the PLL Latch signal FPSEL and FP14 are related to the front panel, not sure how that works yet OE is the EPROM Select  And some NOR logic:   'FP' signals are related to the front panel, the front panel connector:   Amazingly, the entire operating code for the rad...