How do port expanders work ?

[Mark Smith]

I'm a little hesitant to break mine open (pile of junk that it is mind), but what is the theory behind them ?  How do they work ?

Do devices on the expansions get put into slightly different memory localtions are do they all show up at once ?  What about power ?  they all powered at once ?  would the put a strain on the C128 ?

Mark

[Mangelore]

I'm a little hesitant to break mine open (pile of junk that it is mind), but what is the theory behind them ?  How do they work ?

Do devices on the expansions get put into slightly different memory localtions are do they all show up at once ?  What about power ?  they all powered at once ?  would the put a strain on the C128 ?

Mark

Hi Mark,

Well, it depends on the cartridge expander your using.

Most simple ones just interconnect the relevant pins between each slot except for power and then use a switch to enable/disable one cartridge at a time.

Other cartridge expanders allow you to select the IO line. There's two available on the expansion port IO1 & IO2 so you can map to either address $DExx or $DFxx. In theory, you can have more than one cartridges active as long as their address space doesn't conflict.

Oh, here's one I prepared earlier. Includes a fuse, LEDs, reset switch, DIP switches for various lines like GAME, EXROM, IO1, IO2, ROMH, ROML, +5V.... also allows swapping IO1 & IO2 lines on either the second or third slot via four jumpers.



ANyone want one?

[Golan Klinger]

Well, it depends on the cartridge expander your using.

Indeed. I've noticed that some expanders are compatible with some cartridges and not others. I recently acquired a Cardco Cardboard 5 and I'm still trying to figure out all the various features. The thing has more toggles and lights than the cockpit of a jumbo jet. It's quite terrifying. I've also managed to obtain a Skyles 2+1 (later sold as the CMD 2+1), I've got a Aprotek Aprospand on the way and I'm seriously considering buying a Navarone. I think it might be interesting to review them all and put up detailed pictures etc. There isn't very much information out there on these rather interesting devices.

BTW, your expander looks quite a bit like the Aprotek Aprospand.

ANyone want one?

You know I do.

I can't wait to try it out.

[airship]

My Aprospand* just has a slide switch that selects which of three carts is active and a reset button. Very lame, just useful for switching game carts.

How much you want for yours, Mangelore? They'd do well on eBay.

BTW, yours is seriously lacking in one feature - no flat connector at the end for an REU. Those things are unmanageable in a vertical slot.

Edit: * Mine is actually a Navarone.

[hydrophilic]

Good point airship.  Is there an REU with multiple cartridge slots?  

It seems like that would be ideal.  Didn't GeoRAM have a pass-through at the back?  Anyway, I was interested in something compatible with the 1750 and with multiple slots like Mangalore's.

[Golan Klinger]

None of the C= REUs have pass-through and neither does the CLD. I'll have to check the GeoRAM but I'm fairly certain it doesn't. I think airship was referring to something like the Skyles/CMD 2+1 which has two slots that point up like other cartridge port expanders and one that lays flat just like the 64/128's cartridge port. It's quite handy for having something like an IDE64 plugged in at the same time as Super Snapshot.

[nikoniko]

If the GeoRAM has a horizontal passthrough, that would be very sweet. You could then attach an REU to it and use the two together, employing the REU's DMA features to quickly move data between the GeoRAM page at $DE00-$DEFF and main memory. By doing so you could overcome one of the oft-mentioned disadvantages of the GeoRAM -- no DMA -- and shuffle pages between the GeoRAM and system memory at close to half the speed of the REU.

[Mangelore]

My Aprospand just has a slide switch that selects which of three carts is active and a reset button. Very lame, just useful for switching game carts.

How much you want for yours, Mangelore? They'd do well on eBay.

BTW, yours is seriously lacking in one feature - no flat connector at the end for an REU. Those things are unmanageable in a vertical slot.

Yes, I always thought that the Aprospand expanders were very basic with no option to use two or three cartridges at the same time.

I only made a small run of these expanders. My goal was to make one that actually works. So, I spent some time optimizing the track layout on the PCB. I've actually managed to place most tracks on the top layer of the PCB. This makes it very easy to solder all of the pins on the bottom layer for each cartridge socket connector.

What's a fair price for one of these expanders? Would US$ 29.00 be too much to ask?

BTW, it's easy to make a version with a flat connector at the end for an REU

[airship]

Sorry. Made an error. (Yes, I said it!)  My lame three-slot expander is the Navarone. Here's the Aprospand, which has individual on/off switches for each of FOUR ports.

Looks like the last Navarone on eBay went for $37 + $9 shipping, while the current one is up to $15.50 + shipping with 6 hours to go.

The last Aprospand took in AU$31 + shipping, and the one for sale right now is up to $13.99 + $9 shpg. with 3 days left.

Neither has the features of yours, so $29 for one certainly sounds like it would go over. But I'd definitely want the flat connector at the end for the REU. That's a must-have feature to me.

[Mark Smith]

Mine is an Aprospand .. quite sucky I'm afraid ... even if carts are switched off they can stop other carts from working .. the more usual result is the C128 not booting up at all.

[RobertB]

Didn't GeoRAM have a pass-through at the back?

Unfortunately, no.

Truly,
Robert Bernardo
Fresno Commodore User Group
http://videocam.net.au/fcug
The Other Group of Amigoids
http://www.calweb.com/~rabel1/

[Mangelore]

Here's a nicer photo of the expander.



And here's the version with two vertical and one horizontal slot!



I managed to retrofit a standard socket using some header pins. However, there's a bit of work require so I'll be charging US$5.00 more for this version.  There's no point trying to connect a right angle version socket as it ends up sitting on top of the board and is too high for the REU to plug straight it.

Time to update the website

[Golan Klinger]

Very nice.

[airship]

Hey! That's a hack of your own hack! Cool! :cool:

[Mangelore]

strandedinnz had asked me to test the following cartridge combo with my expander:
MMC64, RetroReplay and REU.

Unfortunately, this combo was a no go.

I then tested it using a few other port expanders I had but it still was a no go.

So by process of elimination I figured out that it's the Retro Replay causing the problem.
It must be doing something to the C64 expansion port signals when not powered.

Nothing I can do about it at this point in time. This would require a fair bit of investigating and I suspect the solution would require a number of ICs like tristate buffers placed on the data/address lines etc...

While certain lines like IO1, IO2, EXROM, GAME, ROMH, ROML can be isolated by cartridge expanders, all other lines are interconnected.
I suspect that the Retro Replay hardware is forcing some of these signals into a high or low state when powered off.

If you want the MMC and Retro Replay to play ball at the same time, the only option is to have the Retro Replay plugged into the MMC64 and then plug the MMC64 into a C64/128 without an expander.

Cheers
Fotios

[Mangelore]

strandedinnz had asked me to test the following cartridge combo with my expander:
MMC64, RetroReplay and REU.

Unfortunately, this combo was a no go.

I then tested it using a few other port expanders I had but it still was a no go.

Hi guys,

Just a quick update to let you guys know that I found an easy solution. You need to always have the +5V line enabled on the slot with the Retro Replay cartridge even when it's not used. This allows other cartridges on the expander to function when the Retro Replay is disabled.

Cheers
Fotios

[airship]

Ah! The DDA (Don't Do Anything) chip needs power to perform its function. Makes perfect sense.

[airship]

I know one comes up for sale with fair regularity, but can anyone explain why there are suddenly THREE Aprospands listed on eBay on the same day from three DIFFERENT sellers?

Joe: "Well, Moe, I think I'll go ahead and list that Aprospand I've had for 22 years on eBay tomorrow."

Moe:"Great idea! I think I'll list mine, too!"

Joe:"Doesn't your cousin Schmoe have one? Give him a call and see if he wants to sell his! The more, the merrier!"

[Andrew Wiskow]

Airship, if you're trying to find rhyme or reason to eBay, then you're wasting your time!  

-Andrew

[Golan Klinger]

The reason there are so many Aprospands on eBay at the present time is because a few impatient and poorly informed parties got into a bidding war over this one. When people saw it sell for $96 they immediately put their expanders hoping to cash in. The Aprospand is the most common cartridge port expander out there and is worth about $15-$25 and what's really funny is that because so many people are trying to cash in, there are more on eBay now than ever before which is driving the price below what they might have otherwise sold them for.

Collectors will continue to go after original hardware but those who need functionality are way better off buying a cleverly designed, well made and totally new cartridge port expander from Mangelore. The same can be said for all of his devices.

[Mangelore]

Collectors will continue to go after original hardware but those who need functionality are way better off buying a cleverly designed, well made and totally new cartridge port expander from Mangelore.

I wonder if my cartridge expander will be a collectors item in 10+ years?

[RobertB]

Heh, when our club has an Aprosand, we sell it for a couple of dollars.

Truly,
Robert Bernardo
Fresno Commodore User Group
http://videocam.net.au/fcug
The Other Group of Amigoids
http://www.calweb.com/~rabel1/