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Author Topic: Whats going on with this A500?  (Read 4293 times)

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Offline gunniTopic starter

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Whats going on with this A500?
« on: August 23, 2011, 04:15:25 PM »
Since my girlfriend managed to acquire a box of various commodore goodies a while back I haven't had much time to really investigate other than getting one A500 up and running and doing a bit of gaming and testing out the 3 C64s (2 dead one working but I'll get back to that later).
Today I decided to get the (hideously yellowed) other A500 out of its box to see if it was working and came across a curious switch next to the joystick 1 port. I popped in a workbench disk and switched on, all went well so I decided I would try to boot up after flicking the switch to see what happened. Nothing happened... the insert disk screen was there and the floppy drive was doing nothing.
Even more curious I opened it up and even through the shielding I could see there were "extra bits".
Anyway... can anyone give me a clue to what is going on with this frankenstein A500?






Sorry about the pic quality by the way... any suggestions to the wiring on this memory expansion? The yellow wire has no wire exposed so I don't think its been connected anywhere and the other 2 have been connected together...



Also, with regard to the C64's - the 2 non functioning ones seem to have chips missing although I can't tell if it would be the same chip or not as one is a 64C. Can anyone point me to someplace that might help me identify the missing chips?
Thanks!
 

Offline gunniTopic starter

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Re: Whats going on with this A500?
« Reply #1 on: August 23, 2011, 06:18:03 PM »
thanks guys, I'll open them up again a bit later and have a look :)

the mystery components in the A500 are a Roctec RM2MC 2Mbyte Expansion board and daughterboards, although I'm pretty damn sure the wires on the expansion card itself should not be loose like that
 

Offline gunniTopic starter

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Re: Whats going on with this A500?
« Reply #2 on: August 23, 2011, 07:15:28 PM »
missing C64 chips: from C64C - U9, from breadbin C64 - U18
 

Offline gunniTopic starter

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Re: Whats going on with this A500?
« Reply #3 on: August 23, 2011, 09:29:44 PM »
yup, that one exactly Franko
thanks for your help :)
 

Offline gunniTopic starter

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Re: Whats going on with this A500?
« Reply #4 on: August 24, 2011, 05:29:41 PM »
Quote from: Rob;655921
The SID chips may have been removed to use on dual SID boards.  Have you looked inside the working one yet?

I opened up the working one today... and its missing the SID chip too!
I assumed the missing chips were the reason for the others not working, apparently not!

Further investigation with the A500 reveals the switch previously mentioned is wired to the "EVEN CIA" chip. With the switch in one position the Amiga boots up fine but appears to have only 512K RAM, in the other position the floppy drive refuses to operate. Any ideas anyone?