Re: CBM 610 troubleshooting

From: Christian Dirks <Toast_r_at_IdeaLine.info>
Date: Sat, 26 Jan 2013 23:12:25 +0100
Message-ID: <510454C9.4000803@IdeaLine.info>
Am 24.01.2013 22:40, schrieb Christian Dirks:
> The IEEE bus handshake lines are controlled by the 6525 at U2,
> only the data lines are controlled by the 6526 at U1.
> So U2 may be bad.
>
> I did some tests on a working CBM610:
> It will start up with the PLA removed, but it will not be useable, 
> since there will be no DRAM accessible.
> It will start up with the 6526 removed. (No IEEE bus)
> It will start up with the 6551 removed. (No RS-232)
> It will start up with the SID removed. (No sound)
> It will start up with the 6845 removed. (No video)
> It will start up with the char-rom removed. (Video not readable)
> It will start up to the TIM monitor with the Basic ROMs removed.
> It will NOT start up with the 6525 at U28 removed.
> It SHOULD start up with the 6525 at U2 removed with no IEEE bus. Since 
> this one is soldered in, I did not test it.
After testing this with a CBM710, I am to correct myself:
It will NOT start up with the 6525 at U2 removed.

> Without the Basic ROMs and PLA, TIM will work fine in bank 15. CTRL-G 
> will ring the bell. The IEEE bus will work. (.L "$",08)

Christian

-- 
Christian Dirks
Toast_r@Idealine.info



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