How do you use a multi-slot expander (motherboard)?

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Boray
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Post by Boray »

I suggest you do as vic user describes. Use the 16K as it is and change the switch inside the 8k cart to either block 3 (to get more basic memory) or to block 5 (to be able to play cartridge image files).

The 3K ram doesn't add anything to the basic memory if you have 8k or more put in... Because it has another position in the memory map. But you can use it for ML and pokeing etc...

/Anders
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carlsson
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Post by carlsson »

Heh. I used to use the lathering steel wool too, and we've had the discussion on this forum before. It was here that I learned about the pencil eraser, and I've recently tried it and was amazed how good the result can be. Of course, in the case of a bad solder joint or worn out contact, no matter of cleaning will solve it.

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My 32K memory, which I believe is the same make as Stonan's 32K Rampack but without case. The patch cable is to help the green capacitor (?) to reach through to bottom side of the cartridge.
Anders Carlsson

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ral-clan
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Post by ral-clan »

Leeeeee wrote:Never ever do this with dry steel wool, if you must use steel wool use the type with detergent and use it wet.
Okay thanks for the tip. I wonder....the Mr. Clean "Magic Eraser" (at type of sponge with built in cleaning solution), seems to do wonders for the plastic cases of old computers. I've used it on old VIC-20s and my Amiga and it takes off dirt nothing else will touch....in fact, it made my Amiga look like it was brand new, out of the box again.

I wonder how it would work for cleaning contacts.
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ral-clan
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Post by ral-clan »

I have a couple monster third-party memory expanders as well. Only problem is they all have a mass of DIP switches and I don't have the manual. I have one in a huge black case with four switches labelled "SPECIAL CARTRIDGE" by AUDIO COMPUTERS and by playing around with it I've managed to get 28K on my VIC.

The other is a bare circuit board labelled 16K RAM/ROM EXPANDER and it has about 10 DIP SWITCHES on it!!!! Daunting. I haven't been able to get it to do anything yet.
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Post by carlsson »

Heh, how funny. I also recently acquired a huge black "SPECIAL CARTRIDGE" by Audio computers, but the card inside only has one switch. If you look closely, do the holes for the four switches look like hand made? I think this was a type of common case sold with many bare cards. This is the card inside:

http://sleepingelephant.com/v-web/bulle ... =7552#7552

Maybe you want to open the case (four small screws, I unfortunately dropped one on the floor and couldn't find it afterwards) and see what is inside.

10 DIP switches sounds like an odd number, maybe it is 2*4 to configure each block of 8K to a memory position?
Anders Carlsson

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ral-clan
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Post by ral-clan »

carlsson wrote:Heh, how funny. I also recently acquired a huge black "SPECIAL CARTRIDGE" by Audio computers, but the card inside only has one switch. If you look closely, do the holes for the four switches look like hand made?

10 DIP switches sounds like an odd number, maybe it is 2*4 to configure each block of 8K to a memory position?
Hi, as I recall the hole didn't look hand made, but I will double check and disassemble it when I get home. While I am at it I will disassemble my very early VIC-20 to see the production date sticker.

Might not have been 10 dip switches on the other one, but it definitely was more than 2*4....more like one pair and another set of six, or another set of eight. I will take pictures and post them here.
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ral-clan
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Post by ral-clan »

carlsson wrote:Heh, how funny. I also recently acquired a huge black "SPECIAL CARTRIDGE" by Audio computers, but the card inside only has one switch.
Okay, I opened up my SPECIAL CARTRIDGE:

Image

Here is the back where you can see there are FOUR swiches :o :

Image

Guess, what! Inside it's just like yours. I guess I can get 32K RAM, but I don't know how to set it properly :? . I've only managed to get a totaly of 28K on my VIC by playing around with the switches:

Image

As for making a pass-thru slot...look what is silk-screened on the board: LABEL THIS SIDE. There is a place where another chip can be soldered on (to the right in the photo) marked X-ROM and in small print 8K J1. Why would you want to add another 8K to a 32K cartridge (unless that's the missing 8K and that's why I can only get 28K at the moment)? Or perhaps it's for a ROM chip...in which case, how would that work?

Image
10 DIP switches sounds like an odd number, maybe it is 2*4 to configure each block of 8K to a memory position?
Well here is a picture of the other RAM expander I have. It has 10 switches (well, really 2 and 8 )....what would they be for and why so many??? The board has no manufacturer label, but is marked 16K RAM/ROM EXPANSION.

Image

SO many questions! Can anyone clear up the mysteries?

Very intriguing cartridges.
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Post by Leeeeee »

I guess I can get 32K RAM, but I don't know how to set it properly :? . I've only managed to get a totaly of 28K on my VIC by playing around with the switches:
You won't get 32K free for BASIC as this cart can't fill the 3K hole in the first 8K block in the Vic. For that you'll need a 3K expander as well.
Why would you want to add another 8K to a 32K cartridge (unless that's the missing 8K and that's why I can only get 28K at the moment)? Or perhaps it's for a ROM chip...in which case, how would that work?
It's for a ROM chip. This board can be used in a number of different configurations including with a pass through socket and a 4K/8K ROM probably addressed at $A000
It has 10 switches (well, really 2 and 8 )....what would they be for and why so many??? The board has no manufacturer label, but is marked 16K RAM/ROM EXPANSION.
I think the clue is in ROM/RAM. The eight switches allow you to enable both 8K blocks for each of the four block addresses. I would guess the two other switches are to enable writing to each of the 8K blocks. If you put ROM in them you wouldn't want them to be write enabled as that may damage the ROMs or the Vic.
Can anyone clear up the mysteries?
I could give you a 100% definite answer, but you'd have to send me your carts. 8^)=

Lee.
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Post by carlsson »

I would play around a little. That black 32K System (Audio Computers?) appears to have been delivered as a kit, and the owner decided which kind of switches to solder to it. We have to look where the traces from the switch block go, but my single switch is mounted as this:

Code: Select all

   ___
  |   |
 _|A a|  1 2 3 4
|_|B b|  SW-BLK
  |C c|  5 6 7 8
  |___|
A-2, a-1, B-6, c-5. The other pins on the switch are not connected.

The functionality is that BLK2 is always available, and the switch toggles BLK1. I don't quite understand how it is possible. Your board has four DIP switches, so I would believe every switch toggles that memory block on or off. If all four switches are in position on, you should have 24K expansion + 8K RAM in BLK5 ($A000, 40960). It should be easy to determine.

I suppose an installed ROM will either override the last block of RAM, or only be active when the RAM in BLK5 is toggled off. I realize if I would get two more RAM chips from somewhere, I need to alter the switch or at least shorten the switch block to enable it?

I agree with Lee on that other 16K board. You could try to toggle either of the supposed write protect switches and see if it still accepts POKE.
Anders Carlsson

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Post by Guest »

carlsson wrote:Maybe you want to open the case (four small screws, I unfortunately dropped one on the floor and couldn't find it afterwards)
Heh. I made one last dive on the floor, and next to the rear desk leg, the lost screw lay. I guess not even my vacuum cleaner was able to suck it up.
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Schlowski
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Post by Schlowski »

Funny thing is that I own such a card too :-)

But mine has no switches! Just opened it and saw that switch 3 is shortened and that the 2 RAMs in the upper left corner are missing. effectively I have a 16k RAM cartridge with blocks 2+3 hardwired.

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ral-clan
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Post by ral-clan »

Okay I found an Ebay auction for another SPECIAL cartridge, and the seller tells a little about its features:
It is not a genuine Commodore accessory, but was made in the UK by Audio Computers specifically for the VIC 20. It is different from the standard 16K RAM Cartridge in that it can be further expanded to take;

an additional expansion slot, so that other cartridges can be used on the VIC20 with this one in place
a Machine Code Monitor ROM chip (added directly to circuit board)
an additional 16k RAM to take the cartridge to 32k (the maximum supported by the VIC 20)
Details of the further enhancements are included.

Also has a switch to turn the cartridge off, so the cartridge does not need to be removed if you wish to run a program which will only run on an unexpanded VIC20.
The link is here: http://tinyurl.com/9w8td
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Post by carlsson »

Ok, so out of four identical memory expansions, two have one switch on the left side, one has four DIPs on the back side and one has no switches at all. I must say Schlowski's unit appears least practical, almost like it was custom made for playing Scott Adams' adventures or used in combination with a standard 8K expansion and an expander board.

The comment about a machine code monitor made me curious. I suppose it would look something like this:

Image
That is a C64 Kernel ROM by the way, and no, I didn't solder it to the board and I didn't test it on my VIC.

Anyway, if Lee picks up that one on eBay UK, he can investigate further and tell us the options! :-)
Anders Carlsson

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Schlowski
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Post by Schlowski »

Just to complete the image gallery:

Image

Björg
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Post by carlsson »

Wow, you have the resistor and capacitor installed just right to the ROM slot. Brent does too, but it's not on mine. On the other hand, I have the resistor just below the RAM chips. I wonder which differences it makes. Your board is 16K, but in the low row. Isn't it blocks 3+5 (switch 3 and 4) that are hard wired on your board, making it suitable for 16K cartridge images?
Anders Carlsson

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