[Oberon] Project Oberon on current 'off-the-shelf' hardware

Paul Reed paulreed at paddedcell.com
Mon May 31 02:49:45 CEST 2021

Hi Pablo,

> There is no pattern difference at startup with slide switch 0 off or
> on.

Sorry, I should have been clearer, this switch is only read once, at 
startup, so if you are changing it you have to press PROG to get a cold 
start or BTN3 to get a warm start, and then see the effect of the 
position of the slide switch.

But from the very methodical reports of all combinations that you 
already sent, it seems the standalone PROM BootLoad.Mod program is 
working fine.

So the next thing to try would be either:

1. Hardware route: check the SPI signals to the SD-Card to see if it's 
responding, in particular is MISO (data out from the SD-card) changing 
at all or just staying high, e.g. with oscilloscope or logic analyser;

2. Software route: check using a real operating system that provides raw 
SD-card access in a straightforward way (ie not Windows) that at byte 
offset 10000400 (hex) into the disk you have 8D A3 1E 9B 
(FileDir.DirMark) and at 10000800 you have xx xx 00 E7 (jump to Modules 
body of the inner core).

Chris kindly passed on that you have made progress with your Nexys 4 
setup; if you are using the same SD card and it works on that, then 2. 
is proved so you are probably looking at a hardware issue.


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