Hi All;
Dave, I had really been hoping that I would hear from You soon.. You have a way at getting down to the Meat of the problem..
"" If you want - I can suggest a few tests for you? "" YES, PLease..
"" I have had a quick look at the schematics - and I can't see why any of the MMU registers should increment on a deposit. ""
It is not that the Registers are Incrementing, I have Not tried to access any of the Registers at all..
I am trying to access the Lower 24K of memory, just as though I didn't have a Memory Management set of Boards plugged in to the machine..
I turn on the Machine, with the MMU it requires the DC low and AC low to be pulsed.. Whereas with out the MMU it most of the time does not require this..
I set all the switches to '0' and do a Load address, I then do an Examine.. And it show in the Data Led's all Ones..
I just noticed something.. I have turned it off and am letting it set..
When I first turn on the machine, it shows address of '177776.. and Data is '000000.. I press 'Load Address' and all the led's go out (off)..
I depress 'Examine' , address remains at '000000 and Data is '177777..
De-pressing 'Examine does not increment the Address Led's..
But, Depressing the 'Deposit switch' will increment the Address Led's..
Now if I depress AC and DC low and then press the 'Load address switch' it show Data of '000000,
I can then press 'Examine twice and the Address led Increments to '000002, as it should, repressing 'Examine clears the Address Leds and the Data Leds. and it will NOT Increment the address Led's any more..
But, If I was to switch back to the SBJ Board, the Address Led's would Increment with each pressing of the Examine Switch..
I hope that this is clearer than it was previously..
"" You also should consider adding some debounced switches as well with some patching leads to replace some of your on/off switches. Some signals may be clock lines - and will object to being switched on and off with unbounded switches - this may cause undesirable effects when you are testing and "lead you up the garden path" as a result. ""
It's mainly that I am running out of room on the Board, for much more additions, I know of a change that I would like to make, but there isn't room on the Board to do so and that is to change the ground switches to have drives on them so the Ground signal is not a 'Hard' Ground..
And I knew that there would be things that I would discover that I would need to change, it's a work in progress..
THANK YOU Marty