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+60k Installation
by Ramos/Samar

+60k is a simple RAM expansion created in Poland by Mr.Fiz/Samar. 60 kbytes of extra memory is not that much, but that's enough for simple applications. You can ask if there's any sense of installing such a hardware, when there are many other RAM expansions with more extra memory, for example REU. Not everyone has access to REU, but I think that all of us know someone who is experienced in electronics (or probably some of you are able to install +60k by yourself). What can I tell you? It will be a good thing. It should especially please coders and swappers, as this expansion is mainly directed to these professions. There is also +60k version for C128, which was firstly invented by Mr.Fiz, later developed by YTM/Elysium.

OK. Let's start with installing the +60k in your computer. The scheme can be found on the magazine's disk. There are also "+60k Turbo Assembler" and "+60k Backup Copy" added for your pleasure. The expansion is to be installed inside the C-64, but there's only one little problem with it: you have to own the new C-64 board. +60k can't be installed on the old board.

After installation we have two banks of memory. One of them is a standard memory, the second one is an extra memory $1000-$ffff. You may ask why not $0000-$ffff? Well, this is caused by the fact that coder has to have some memory in order to be able to switch between banks. That's why we have 60 kbytes of RAM at our disposal, and not 64 kbytes. To illustrate it, I'll give you an example. If a program which is running, let's say, at $2341 would like to switch RAM into the second bank (means our extra memory), a coder would have to copy the whole program into the expansion, so that processor won't hold up after switching. And now if you have your procedure to bank switching at $0900, there's no problem with that. You just switch between two banks $1000-$ffff without causing any conflict with a program that is already running. One important defect of this expansion is the fact that in an extra memory VIC can't see RAM. So if you want to see the picture which is for example located at $2000, you have to copy it into a standard memory and then show it. I heard this problem had been solved by Soci/Singular, and I hope that he will share it with us one day.

Now we can go straight to the process of installation... In case you're not experienced in electronics, you should ask someone for help. First you should prepare a soldering iron, a few conductors, one switcher and the following parts: IC 74LS00, IC 74LS02, IC 74LS139, IC 74LS174, 2x IC 4464 (additional RAM), and IC sockets 2x with 14 pins, 2x with 16 pins and 2x with 18 pins. If you want you can build your +60k on a circuit board.

When you have it, we can start installing the expansion... Firstly unscrew your C64, and find the 101 Resistor on the main field. Remove it using any tools. Put IC parts (7400, 7402, etc.) on the separate field (look at picture file added to this issue of magazine). Get the VIC out and connect its pic 10 to pin 12 of 74139 dice. Then connect "female" pin 10 from VIC Base to pin 15 of 74139 dice. You have to follow the same steps connecting IC's 4464, but there you have to conect pin 16 of this dice with pin 4 of 74139 dice.

On the picture (find it on the disk), there is a little mistake! The 4464 dices have 20 pins there, but in fact they have 18 pins! So pin number 16 is the third one from right side, OK?! That's all about the installation process of +60k RAM expansion. Check out the installation picture file and some extra tools for this expansion that you should find on the disk together with "Attitude #6".

We can move between RAM banks using the memory location $D100. When having value $00 there, we are using the "standard" C-64 memory, value $80 means that in the area $1000-$FFFF we're using our RAM expansion bank.

Except for some useful tools, there have been released some digi samples for +60k (by Kosa and Soci). The RAM expansion is also used by Warlock's collection "The Orbital Petrol" and Polish disk magazine "Newspaper".

The +60k is owned by quite a few people in Czech Republic, Hungary but mainly in Poland. I hope that after reading this article the amount of sceners owning the +60k will grow bigger in the other foreign countries, so that we could set the new standard of developing our releases!

Exclusively for "Attitude" by...

(English translation by CACTUS/OXYRON)

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