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Re: Games we never had
Posted: Sat Nov 22, 2014 8:00 am
by sixxie
The implication is that the address above the last tested good one is 16389: (32768 - 24871) + 8492
Try:
Code: Select all
POKE 16389,255
PRINT PEEK(16389)
POKE 16389,0
PRINT PEEK(16389)
That should hopefully isolate which bit has the fault, which could suggest a single RAM chip to replace.
Re: Games we never had
Posted: Sat Nov 22, 2014 9:37 am
by Commodore
Thanks sixxie and zephyr.
I shall certainly try those, and report back.
At the risk of sounding a bit thick; should I put line numbers with those commands?
The Dragon is a new system to me. I noticed that ? is short for print, the same as CBM Basic V2.0 (also by Microsoft), does that also extend to things like POKE being P shift O? etc etc. I only ask as I haven't yet had a chance to try it, and I have to pack the Dragon away after each time I've used it, so it's not set up at the moment.
I might try it later or tomorrow.
Re: Games we never had
Posted: Sun Nov 23, 2014 12:31 am
by Commodore
I tried the commands as described Sixxie.
The first PEEK returned 253, the second PEEK returned 0. So it looks like something is wrong then I think.
I worked out that the CBM basic P shift O etc doesn't work on the Dragon. Is there a way of shortening the commands? I know Acorn equipment used the first letters and then . For example O. L. was OLD LIST.
Is there a hope that this Dragon 32 could be fixed?
Re: Games we never had
Posted: Sun Nov 23, 2014 9:02 am
by sixxie
So it's possible that the only bad RAM chip is that handling bit 1 - IC7 according to the schematics.
If you check what's on your board and can source an equivalent replacement, you might be able to fix it.
Re: Games we never had
Posted: Sun Nov 23, 2014 9:42 am
by Commodore
OK< thanks sixxie. That's great.
Re: Games we never had
Posted: Sun Nov 23, 2014 1:38 pm
by zephyr
Commodore wrote:Still nothing will load. It gets so far through the process and then the cursor freezes, the .wav file ends, and the screen does not change.
I tried Chuckie Egg, Airball and Frogger.
I think I have found the problem though - BAD RAM.
When I type ?MEM, I get 8492, which is rather lower than I was expecting, just about 8K.
I thought I'd try this as it was reminiscent of when a 48K Spectrum I had suddenly decided it would be a 16K Spectrum. The good news is the Spectrum was fixed, I don't suppose a Dragon is quite such an easy proposition. Shame if that is the case.
It would be good if anybody could confirm my diagnosis, and maybe suggest a Dragon Doctor.
Just a quick post to let everyone know that the above topic of the broken Dragon 32 has now been continued in
this thread.
Re: Games we never had
Posted: Sun Nov 23, 2014 11:17 pm
by Commodore
Thanks Zephyr, and apologies for the confusion caused by absentmindedly posting on the wrong thread!