| Posted By
vigsa (HUN)
on 2008-12-26
09:37:52
|  Missing BASIC ???
Hi,
I've just got a "new" PLUS4 for XMAS. I was wery happy to get one after so many years. Unfurtunately it doesn't work. When I switch it on, the blue frame and a the white screen appears, and the cursor is in left-top of the screen. But no welcome message, and no "ready". When I press "Run Stop" and reset, I can reach the assembly interpreter. Everything works (typing, listing memory, etc) but when I want to exit to BASIC (with X) then it stops working.  Can somebody help me, please?
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Posted By
Rachy
on 2008-12-27
03:04:54
| Re: Missing BASIC ???
As it seems the initialization procedure stopped somewhere, you might try to remove the chips which are in sockets clean the socket and push them back again.
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Posted By
vigsa (HUN)
on 2008-12-27
12:13:59
| Re: Missing BASIC ??? -> Buggy BASIC ROM?
First of all, thanx for the tipps. The motherboard and the chips/sockets are now clean, but the problem still exist. I Found a new sympthom: when I list the contents of memory at the address of 8000 it does not seems to me allright. It changes! (M 8000, D 8000) For example: M 8000 : F0 F0 F8 F0 F0 FC F0 FF. After 3 sec, M800 : F0 F0 F0 F0 F0 FC F0 FD. I tried other memory addresses, but only 8000 and above are changing. When I look at the code (D 8000) it is not like a healthy program.
Any other idea?
Question #2: Basic should start with G 8000, isn't it?
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Posted By
Rachy
on 2008-12-28
03:13:31
| Re: Missing BASIC ???
That content for address $8000 is wrong. As it seems either the BASIC ROM chip or the 3-plus-1 chip is broken. You might try to remove the 3-plus-1 chip, which is useless anyway.
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Posted By
vigsa (HUN)
on 2008-12-28
19:21:44
| Re: Missing BASIC ???
Sorry, but which one is the 3-plus-1 chip?
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Posted By
Rachy
on 2008-12-30
04:46:58
| Re: Missing BASIC ???
I have removed them from my Plus/4 a long time ago, so I don't know the exact chip ID numbers, but the two which marked on the motherboard as U25 and U26.
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