Technical memory question

Boray · Post by **Boray** » Sat Jul 17, 2004 4:41 am

I have a vic-1020 expansion box which gives my vic-20
six cartridge slots. Now let's say I have two 16K carts
with switches. On cart A I have selected block 1 and 2.
On cart B I have selected block 3 and 5 and totally I
will have 32kb of expansion ram. So far so good. But now
I want to plug in my Hesmon cartridge as well (that uses
block 5). Can I then just unselect block 5 on ram cart B
and then get 24kb of ram together with Hesmon? In other
words: If you just select one block on a 16K ram cart, will
the computer/expansion box then recognize the cart as
an 8K cart instead? And is this allowed?

/Anders

Leeeeee · Post by **Leeeeee** » Sat Jul 17, 2004 5:55 pm

Is the select on the RAM cart an either of two or a enable one of type? I.e. are there four on/off switches for each 8K bank labeled 1, 2, 3, & 5 or are there two switches for each 8K bank labeled 1-3 and 2-5 ?

If it's the first, four on/off switches per 8K bank, then yes it will work [1].

Lee.

[1] Usual disclaimers apply. 8^)=

Boray · Post by **Boray** » Sun Jul 18, 2004 10:31 am

Thanks! There are 4 switches for every bank...! So the computer just ignores the memory if none of the switches is selected then? So theoretically, I would be able to fill up all six slots with carts where no block is selected then without any danger? ...I mean, the memory chips are still connected to the computer even if no block is selected...

/Anders

Leeeeee · Post by **Leeeeee** » Sun Jul 18, 2004 6:03 pm

It should be ok like that. The reason I say should and not will be ok is that it really needs a pull up resistor in the cart to ensure that any lines not selected stay inactive (logic 1). Some carts don't bother with this resistor, including carts I have, and I've never had trouble but a friend did have occasional crashes with such a cart in place until we modified it.

Tha fact that the chips are still connected won't matter as long as there are no conflicts between carts.

Lee.

Boray · Post by **Boray** » Mon Jul 19, 2004 2:54 pm

So the worst that can happen is that the hardware gets confused then? No risk of damaging anything then?

/Anders

Post by **Jeff-20** » Mon Jul 19, 2004 9:58 pm

I have a 6 slot HES hardware... the buttons seem to indicate that I can select more that one slot at a time... I have yet to play around with it.

I have a switch able 16 ram cart... what could I do with the HES hardware?

carlsson · Post by **carlsson** » Tue Jul 20, 2004 12:12 am

I have a "dumb" three slot expansion board, and more than once, I have plugged in both my memory expansion and a game cartridge without either taking obvious damage. I even configured the memory to map all blocks 1,2,3,5 and since I place it "before" the game cartridge, VIC sees the expansion RAM rather than ROM.

Although not recommended to do, I even run-time reconfigure the switches so the RAM blocks (in particular block 5) are not available anymore. I suppose this could damage something, but not yet... instead I get Basic access to PEEKing and SAVEing the ROM data from the cartridge without having to modify the actual cartridge.

Boray · Post by **Boray** » Tue Jul 20, 2004 8:36 am

Maybe I am a bit TOO careful...

Jeff, that would probably be exactly the same thing as a vic-1010 or vic-1020, but with buttons for extra control over it. Mine has no buttons at all... So everything I plug in will be mounted into memory.

/Anders

Leeeeee · Post by **Leeeeee** » Tue Jul 20, 2004 10:53 am

So the worst that can happen is that the hardware gets confused then? No risk of damaging anything then?

There is always risk, but probably less than swapping carts each time.

Lee.

Boray · Post by **Boray** » Wed Jul 21, 2004 10:30 am

Hmmm.... My brother told me about a guy that always swapped carts with the power on and then started them with a reset button, so I guess these computers are pretty robust.

Thanks!
/Anders

carlsson · Post by **carlsson** » Thu Jul 22, 2004 12:30 am

Maybe that guy was lucky to have carts equipped with the pull-up resistor for extra safety. When it comes to damaging the cart, I think dropping it to the floor may cause more damage than hot-plugging? A friend of my brother had a couple of VIC-20 cartridges, of which his copy of Road Race (IIRC) was totally garbled up graphics wise due to inproper handling.

Boray · Post by **Boray** » Thu Jul 22, 2004 10:13 am

Another memory question... Does memory circuits get more "sticky" with age? Because 17 years ago when I loaded cart images into my memory cart, I could just switch the power off and on and then load another game. But now, I have to wait several minutes with the power off, or else the computer won't start again. Like it's still remembering the autostarting parts of the game.... So now I have to unplug the cart, change the switches so that I use other memory for block 5, and then it starts again....

/Anders

Leeeeee · Post by **Leeeeee** » Thu Jul 22, 2004 11:26 am

Some CMOS RAM can hold it's data with less than 1V on the supply lines, it may be this that's making it appear 'sticky'.

A quicker option would be to switch block 5 off, reset, switch block 5 on. If this is too fiddly as is then wire an external switch, on short leads, across the block 5 switch and leave that 'off', then use the external switch.

Lee.

Boray · Post by **Boray** » Sun Jul 25, 2004 7:48 am

I just equiped my ram cart with an external block 5 switch and it works great! Thank you Lee!!! But why does the leeds need to be short? I forgot about that so now it is about 30cm. Maybe I should make it shorter then...?

/Anders

Leeeeee · Post by **Leeeeee** » Sun Jul 25, 2004 9:47 am

All wires act as antennas and will radiate any signals on them, they can also pick up outside interference. The shorter the wire the less it will do this.

30cm is ok but I wouldn't go much longer.

Lee.