a2retro blog

Well…. the smoke test failed …. I could smell burning somethng ….. turns out I made a  very big mistake … when looking at the memory expansion connector in the IIc memory technical reference and the IIc technical reference, I thought the pinout was as if you were looking down on the the connector in the machine … what they are actually showing is the memory connector on the card facing up … needless to say I had every thing ass backwards … rather then go an rip every thing apart I have used some lead cables and a IDC 34 connector to fix things up for now …

So once I got the system booting again, I was able to successfully program the XC95108 with the jed file I programmed. Next I tried executing the diag code for the memory card @ c40a … it failed with an address error … so thats where I will start my investigations .. I will put the logic analyzer on the Apple side to start to make sure the CPLD is getting all the signals properly … then once I have determined that I will put the probes on the sram side to make sure the ram is reacting properly.

All the Uthernets are now out the door now … so hopefully I can get back to working on IIcmxp …

Wow, they went fast … I have already ordered 25 more modules and PCB’s - realisticaly it will take about 1 month before I am ready to sell again … so send me a email if you want to get on the notification list.

I have 3 prepaid orders to fill and then a supply of 28 cards available for sale. Anyone on my interrested parties list should have gotten a note from me.

Also I am half finished wiring up the 5v SRAM interface for the IIc. Hope to try that out in a few days.

If anyone knows of a PCB assembly house that will do microBGA or CP scale packages for a reasonable price then please drop me a line.

If you have been following along with my plans, you know that the IIcmxp consists of a 1MB  SRAM memory upgrade, SDcard storage and a communications module (I’d like to support both a wired and/or wireless option).  It’s hard to keep on track with a method for tackling this project as I find my self swinging from just working on one aspect of the project to trying of accommodate any of the 3 aspects .ie how they will coexist with one another. I think I have come to the conclusion to develop 3 separate projects and then figure out how to adapt them to live nicely together after the fact.
Which leads me to my next topic … as I stated before I think I have the SRAM down .. still needs to be tested as I have not wired up my original IIcmxp protoboard although i did make up a wiring map for it.  The SDcard is on the back burner at the moment .. still not sure if I want to use a co-processor (like Alex used)  or do it entirely in the CPLD .. which brings me to my 3rd aspect … communications options …

While I am still considering the option to use the approach like the SPI2CF project (again requiring that co-processor like Till used) … I also remembered that I bought the AirDrop-P from  Fred Eady. I never did get that going after buying it … so I brought it out of moth balls, dug up the latest code from the Yahoo group and got it working with my 802.11 infra in the basement including 128 bit wep.  Of course all the hard work was done for me but it took some tweaking to get things complied and runnings smoothly.

With that working I thought it would be a fun challenge to get the IIc to talk directly to the CF card for the purposes of i/o. While the A2 platform already has CF support from other vendors, these are (from what I know) all used in true -IDE mode and do not support cfio operations. I worked on some ABEL code that should let me talk to the cfio registers.

So how to test this ….. hmmm … I decided to take my IIc break out board that I used for /devsel testing and I added a few components to it … namely a CF socket and one of Justins XC95144XL CPLDs .. I decided to keep the XC9572XL already in use (wired) for /devsel, I will use the rest of the i/o in that cpld to do level trasnlation from 5v to 3.3v on any required remaining signals from the IIc (except D0..D7).  The XC95144Xl will be used for the CFCard logic and SDCard logic when I get there.

and this of course needs to be wire wrapped .. my next work item then is a wiring map for the CF interface .. once thats done then I will start porting some of Fred’s routines via cc65 and we will see where she goes from there …

In my search for CPLD breakout boards I met a new friend in Taiwan. His name is Justin. He is the manufacturer of some neat Xilinx breakout boards for the XC9572XL and XC95144XL CPLD’s.

He sent me some samples. These should come in very handy.

Full size picture - http://www.a2retrosystems.com/images/IIcmxp/CIMG4064.JPG

I spent some free time working on a breakout board for the Apple II bus. The idea here is that you plug the bottom end into the Apple II bus connector and then use the top card edge for header attachements or a card edge to ribbon cable connector. The middle holes would typically be used for a dual row header that one can use to tap into the Apple II bus signals with a logic analyzer.

While James Littlejohn of 8bitsystem.com has recently released the LittleProto II prototyping board for the Apple II (available from ReactiveMicro), sometimes there are things you want to do and a breadboard is not suitable for a variety of reasons.

As design exercise I plan to make some various breakout/adapter boards for myself. I want to learn how to panalize things, so I take advantage a single PCB run with multiple items if i need to.

I posted an offer on comp.sys.apple2 to make a run of these boards. The idea was the if enough people wanted a few each i would just run off a batch … seeing as no one has spoken up so far I will just continue you on with my panelization project and only make a handful for myself for the time being.

I have been following the OLPC movement for some time now. When I heard about the G1G1 (Give One Get One) program I decided I wanted to participate. I ordered mine the first day (Mid November if I remember correctly) and finally received delivery a few days ago.

It’s a pretty cool little system. It is taking me a little while to get used to the small display. I just installled opera which makes for a much nicher browsingn experience then then the built-in simple browser. I want to see kegs for linux running on this little beast as well as the Linux port of AppleWin. If your an Amiga fan at all the Amiga Forver emulator already runs on the device. The screen rez is a nice 1200 x 900 (200DPI) on a 7.5″ LCD.

 I will post a picture of kegs for linux running on it once I get it compiled and running.

Not much happened with the project over the Christmas holidays .. we had a sad event in our house … my Mother-inlaw passed away on Christmas Day … she wasn’t your stereo-typical Mother InLaw thats for sure. We are going to miss her greatly but now she is with those who have gone before  …

Plans now are to split the efforts on two fronts …

 a) wire up the original SRAM portion of the IIcmxp prototype. This is all 5-volt stuff - just to prove that it works - I am pretty confident it will. I plan to possibly detach the AVR/CPLD/CF portion and glue that onto the development board pictured before.

b) carrry on with the development board and decide/work out how I will do the SDCard interface. ie with or without a CPU helper. I have been reviewing Alex Freed’s AVR, Verilog and 6502 code from the  Pseudo Disk  project to see how it ticks and to determine if I can re-use any of it for this project ( the ProDOS block driver portion that is not the 140K disk image part) . The alternative is to add a SPI Master port in the CPLD and interface that directly to the 6502  .. the kicker here is that there are only 4 i/o addresses available in the memory interface  A0 & A1 (to keep it compatible with the original memoruy expandable IIc. The IIc+ added A2 and A3)

I want the i/o interface to be as transparent as possible so that the RAM interface works with all previous software that used it. I need to determine how to piggyback the flash (SDCard Interface over top of that) I have some ideas which I have been kicking around for a while. I will document those in my next post. I would certainly welcome any feedback on that info when posted.

 Over and out

 Glenn

Since the Apple IIc memory expansion port was not blessed with a /devsel signal, one must create ones own from address lines A4..A15 (inverted where required) and ph(zero). Pretty simple to do with a PAL or CPLD.

For testing purposes, I have added a flip-flop to the ouput of the equation so I could see this in action. The net result is that the LED toggles on or off every time a memory address is read/written to $c0c0-c0c3.

Making this little side board has been interesting and could come in handy for protoyping new ideas.

I did run into difficulties with one of the cables I made … it must have an intermittant short .. it worked for a while then started giving me grief….