Hello, can someone please tell me the correct configuration for the 2001-8 1977 memory banks setup or link me to a site that has this configuration setup ?
It seems that when i swop just one RAM i get a lower or higher amount of free memory.
I want to get the standard 7167 but when i swop with an other 2001-8 mainboard i can get 6143 or at some point even more then 7167 !
When i take out the two RAMs on the highest bank it even drops to 3200K, by only taking out the last two RAMs.
So what is the correct setup from bank 1 to 8 as some RAMs have other numbers on them.
M experience with swapping PET RAM has been problematic. There may be a more technically satisfying answer, but I believe the problem is the related to years of residue/corrosion on the sockets themselves. You may want to try seating/removing/reseating an old chip over and over again to scratch of the grime.
Also a chemical "boardwash" spray may help, although I can not recommend any because I have always feared causing damage to those old cold solder joints.
I am sure someone else will have a more knowledgable solution, but those are my thoughts.
There are four different board versions used in the pet2001-8.
In two versions the 6550 ram is used, the other two versions the 2114 is used.
I'm guessing you will have a pet with 6550 ram in it, because unfortunately it's quite common that these fail.
The 6550 ram is far less reliable that the 2114 ram.
Normally these 6550 ram are quite hard to come by, fortunately for you someone is selling a lot of them on ebay right now!
H Donni, thank you for your reply and the mention of the RAMs on Ebay, i will sure try. What i do not understand is that it makes a differents when i swap a 6550-2778 with a 6550-1978 RAM, i will get a higher or lower free mem amount. And i see 4 different 6550-**** on the banks ! (also on my other PET i used to swop the RAMs around).
Can you or someone explain the different numbers and what they do with the free amount, as it is changing when i replace 2278 with for example with a 1978 or other number. BUT......not always, so there is someting going on with the specific numbers on specific banks.
I must say i was yesterday VERY LUCKY in my swop attemps and finaly did get 7167 Bytes free
Even when i connect a Expandapet memoryboard it starts up with 31743 Bytes free so thats working great to !! (no need to address the extra mem with the SYS command, strait from the start it gets the 31743 free)
So at last i can start playing.......... )
Those four numbers like -2778 you mentioned are just the production date(week 27, 1978).
Like I mentioned before, the 6550 ram is not very reliable so it's likely that you have more than one defective 6550 ram each giving a different memory count.
An easy way to test each ram separately is to swop it with the video ram.
If you turn the pet on again and the picture is garbled or the characters you type in do not correspond with what's on the display, you have a defective one!
Hallo Donni, grappig dat wij via Canada over dit geval zitten te mailen, maar het lijkt mij beter om in Engels verder te gaan zodat iedereen er iets aan heeft, en bedankt voor je input
Hi Donni, ok, this is clear about the numbers on the RAMs....
Am i correct when you talk about the video RAMs it are the two 6550 RAMs in the middle to the end of the mainbord ?
I have an other PET 2001-8 with a screen full of numbers on the startup so one or both video 6550 RAMs are defective, richt ?
CBdicX wrote:
Am i correct when you talk about the video RAMs it are the two 6550 RAMs in the middle to the end of the mainbord ?
Yes
CBdicX wrote:
I have an other PET 2001-8 with a screen full of numbers on the startup so one or both video 6550 RAMs are defective, richt ?
And No.
If you have a screen full of characters on startup and the pet does not respond to commands, it's likely one or more rom's are defective.
These rom's are not easy to come by, so a while ago I took the trouble of designing and building an adaptor to replace the ram and rom in a pet2001-8.
Picture:
A German guy is selling something similar.
Check it out: http://x1541.de/
The rams are in pairs, top and bottom being one pair.
so if you remove a chip from the lowest pair you will drop memory down to the lowest working pair.
Use a Ink eraser on the pins of the ram to clean them, gently of course.
this is like a fine sandpaper and will remove any corrosion.
