VIC-20 Multicart

[gklinger]

That joke reminds me of a humourous saying amongst hardware technicians. "If it isn't on fire, it's a software problem."

Sorry about the OT silliness.

[Jeff-20]

I wish people would count to 10 before they posted.

This is the new rule. The "Friendly Computer" should have a friendly community.

[PaulQ]

To be honest, this is the friendliest internet community I've come across. That's probably why I'm hanging out here now. If this is as heated as it gets, there is nothing to worry about.

I think if we all inject some humor when things start to get heated, that will help to keep things friendly. Nothing like a good (or bad) joke to diffuse a tense situation.

[eslapion]

Sorry, I realized I'd forgotten to make the mental flip between acitve high and active low logic about an hour after I wrote this bit. It wouldn't work as written. Rather than shifting around AND gates, what's needed is ORs (negative logic ANDs) on the latch enable inputs of the 373's to tie the new latch in with the logic from the /BLK selects. Either diode ORs can be used, or an OR logic package introduced while keeping the rest of the circuit as-is.

In spite of the error, I think the idea is clear here. It's possible to do without the 273 and the power up reset circuit without adding a lot of other stuff to make up for the loss. With the proper choice of gates for the other logic, there won't need to be any more ICs added to make up for the 273 going away. I'd come up with better now, but it's late and I'm tired.

The only thing that bugs me is these 8 resistors but otherwise this seems functional.

Concerning the missing OR gate (and that's why I originally mentioned an LS32) that could be easy. On the ultimate expander, I need 5 AND gates but I only get 4 out of an LS08. I make a 5th one using 2 diodes and a 10k resistor. In this configuration:


In this specific case, I had to use expensive pair of 1N6263 diodes with very low voltage drop because any voltage above 0.7v runs the risk of not being properly seen as a 0.

However, with an OR gate, anything above 2.5v can successfully be seen as a one and so the voltage drop of the diode is much less critical.


A 1N6263 costs 0.50$ each. A 1n4148 costs only 0.06$ each and 2 could make for a cheap extra OR DRL gate. At 4ns, the reverse recovery time of a 1N4148 is much slower than that of a 1N6263 but it is still much faster than the requirements for this application.

I must also admit, it is much less expensive than an extra LS373.

Still, a picture of the exact schematic you have in mind would be appreciated.

As for the 2 inverter latch, I suppose a small capacitor and resistor at the right place will ensure it has the desired state at powerup and the very first access to IO3 will switch it's state.

[Centallica]

To be honest, this is the friendliest internet community I've come across. That's probably why I'm hanging out here now. If this is as heated as it gets, there is nothing to worry about.

I think if we all inject some humor when things start to get heated, that will help to keep things friendly. Nothing like a good (or bad) joke to diffuse a tense situation.

Yes, very true here it's mostly tame...Rec Games Pinball is a "Troll's Heaven" lately There was a thread that just came up with a racist remark that I was going to fire back at but I don't want to "feed the trolls" as this is what they're looking for "attention"

Humour is great...hope there's lots next Saturday Night

Brian

[Jeff-20]

To be honest, this is the friendliest internet community I've come across. That's probably why I'm hanging out here now. If this is as heated as it gets, there is nothing to worry about.

I think the size (number of members) of the forum makes a BIG difference. I feel like Digital Press is too big of a community (I feel overwhelmed and read only 1%), and SegaXtreme is too small (lots of inside jokes). No disrespect to either community. Both are great, but Denial has reached a comfortable, friendly size for me.

[ral-clan]

Denial is the only online forum I have stuck around on and enjoyed. I can only cope with one forum (I also post occassionaly on Amiga.org but am more of a lurker there). Any more and I'd be on the internet 24 hours a day (I already spend too much time checking the forums).

[eslapion]

Schema: Your feedback would be welcome here...

Saundby: Would you care to give us a picture of the corrections you had in mind? This would help if you feel your suggestion is worth implemeting.

[Schema]

I'm a bit out of my depth on this particular issue, but I agree a schematic would be very helpful for everyone to evaluate saundby's idea.

We also need some breadboarding / prototype boards to really try the ideas out, I think. Are we at that stage yet?

If both approaches work equally well, then another criteria is which is cheaper/easier to manufacture.

I'm willing to put up the money to get these made, so I'd like the design to be the simplest it can be as well has have it checked by many people

[KilrPilr]

I too will cough up some dough to make the boards and whatnot. Please remember though that I have approx 50 8meg eproms and the programmer to program them.

Here is the newest version of the cartridge images for the multicart. I also updated Leif's master list and made a totals text for the lot here.

Leif, could you go through the master list in my zip file there (especially page 2) and finish it off. Thanks

Hopefully Mayhem can dump his Mobile attack and frogman carts soon and Joqi can add his unheard of Vic carts to the lot as well.

http://members.shaw.ca/vic20/VicCartRoms.zip

Please download and double check or tripple check and let me know if you have any images not present.

[eslapion]

We also need some breadboarding / prototype boards to really try the ideas out, I think. Are we at that stage yet?

I am not sure but I believe I did mention I plugged an LS373 on a prototyping board with a vectorboard and wires going to the VIC's expansion port.

I used it to control 8 LEDs by poking to 40959. That's how I realized there was a consistency problem with the startup latching.

If both approaches work equally well, then another criteria is which is cheaper/easier to manufacture.

I'm willing to put up the money to get these made, so I'd like the design to be the simplest it can be as well has have it checked by many people

I think Saundby's approach may be cheaper but the dual chip approach should be easier and quicker to solder.

There is also the big question, do you guys want to go for surface mount or use good old through-hole technology?

[saundby]

You're headed the correct way with the diode gates and ideas on the latch. I burned up the time I have to post for now on Bagnall's Commodore book, unfortunately, no time to draw up anything now. I've had a project get hot over the weekend so I'll only be stopping by at "break times" when I can over the next week or so.

If you want to move ahead on a short schedule, and the board is working well for you with the current circuit, and the price of the extra 8xlatch isn't a huge problem you might want to move into testing it with as many systems as you can. One of the things you may want to do is look at different 6502s as much as you can. The clocking in the Vic is pretty predictable compared to a lot of other 6502 systems, but you'll want to make sure that the change from, say, an early MOS 6502 to a later one, or changes between Rockwell, Synertek, and WDC (especially) don't break your latch's gating. I don't want to seem to harp on timing, but the phase 2 clock's purpose is to gate data into and out of the 6502 (phase one drives the insides of the 6502.) While the other signals can work for moving data, the data's only guaranteed to stay good for 11nS after the fall of the phase 2 clock, or thereabouts--going from memory, no time to chase manuals now. Often the other signals outlast the data depending on your particular 6502.

If I get a chance to draw up an alternate layout, I'll do it and post it. But don't count on much from me for the next week. When I'm not on my real work, I'll probably be letting steam run out my ears while reading the Bagnall book and avoiding electrons for a short while before donning the harness again. Oh, and maybe I'll sleep a little, too. That sounds nice...

-Mark

[Schema]

I am not sure but I believe I did mention I plugged an LS373 on a prototyping board with a vectorboard and wires going to the VIC's expansion port. I used it to control 8 LEDs by poking to 40959. That's how I realized there was a consistency problem with the startup latching.

Yes, I remember that. That's great, but I'll be happiest once I see (or hear about) some code running from Cell 0 in a ROM.

I think Saundby's approach may be cheaper but the dual chip approach should be easier and quicker to solder. There is also the big question, do you guys want to go for surface mount or use good old through-hole technology?

I think it would be worth having them populated by the board design place, or elsewhere if you know a board manufacturer who could do that. I don't see any reason to have you hand-make each one, unless you really enjoy it (which you may!) or unless the cost is totally unreasonable. We haven't discussed numbers, but I think 100 units with a selling price of $50 should be the target.

With that in mind, how does that affect the choice of surface mount vs. through-hole?

If you want to move ahead on a short schedule, and the board is working well for you

Well, there's no real rush on this, to be honest, we're just pushing ahead because we've got so much momentum going.

In terms of deadline, it would be great if we had something to demo in time for the C4 Expo in May. Even a prototype board would be fine. eslapion have you thought of going? I'll probably be there.

[eslapion]

I think it would be worth having them populated by the board design place, or elsewhere if you know a board manufacturer who could do that. I don't see any reason to have you hand-make each one, unless you really enjoy it (which you may!) or unless the cost is totally unreasonable. We haven't discussed numbers, but I think 100 units with a selling price of $50 should be the target.

With that in mind, how does that affect the choice of surface mount vs. through-hole?

I know a couple of places that will do the complete job of making the board and populating it... minimum quantity is 2000 units...

In other words, there is no way you can get only 100 units done like that... AFAIK... and therefore it will have to be done by hand.

Now you know how it affects the choice of surface mount vs. through-hole

In terms of deadline, it would be great if we had something to demo in time for the C4 Expo in May. Even a prototype board would be fine. eslapion have you thought of going? I'll probably be there.

I am not afraid to say that because of a small incident that occured back in 1991, I have a criminal record. I was awarded a pardon by the government of canada many years ago. Since the US does not recognise the canadian pardon, I would have to pay 700$ US for a security investigation. Since I have been diagnosed with Asperger Syndrome, I was told by an experienced security expert that it is almost guaranteed that I would be denied entry in the US.

Since trying to be allowed into the US would essentially result in a denial, that amounts to a donation of 700$ to people who essentially do everything they can to cause stigma and destroy my freedom.

In solidarity for the 3 million canadians who have a criminal record and are also persecuted by the US administration in this manner, I refuse to spend money for something like that.

...welcome to the Maher Arar era...

[PaulQ]

Hey, I don't have a criminal record, and I don't really like to visit the states either. I have my own border story to share.

Back in 1997, I was offered a job with an American company as a computer programmer. I was supposed to be able to work there under the NAFTA agreement. Under NAFTA, I would have had to have a certain amount of experience in the industry before I would qualify. Since I worked a summer at EDS and continued on with a work study program while I studied afterwards, I figured that counted as industry experience. So did the lawyers at the company that wanted to hire me. However, the border official decided he was suddenly some kind of authority on my trade, and determined that I didn't have enough experience, and my pre-graduation experience did not count. The border official was judge, jury, and executioner; as well, he was a complete buffoon who treated me and my spouse as criminals. He warned us to not to try to cross the border at another location because I was now in their "System." Since there was nothing left to lose, I told him what I really thought of him and his country (words which do not belong in a "Friendly" forum) effectively burning that bridge, and headed back to Canada.

I think they're a bunch of assclowns trying to compensate for the fact that they've pissed off the rest of the world, and people like you and me end up becoming the victims. As such, I have no desire to visit any destination in the US anymore.