6502.org

after making one of these basic units myself with just the board and few extra bit, I thought I`d try the Ram add on too.
It`s not going well for some Utterly Unknown reason (to me anyway).
I`m using the Same Ram chip (I bought 2 of them), the wiring has been checked 3 times by me on 2 different days and also someone else and it`s correct.
I`v followed the instructions perfectly, on 2 different days and get the same results (it not working).

in effect, what I get is the Initial screen with the options, I press `C`, the Memory Size? comes up quite slowly, like a visible one letter as a time action.
Pressing Enter again will skip the cursor to the next line and then it does Nothing at all?
not the expected Terminal Width prompt or anything, it just sits there (and will sit there overnight too, I tested it).
So there IS a problem here, I just can`t figure it out, I`v also tried pulling the CPU clk down to half a MHz to see if that`s the problem, it seems not.
pulling the RAM chip out leads to a Fail at the start, there`s nothing as all Visible on the monitor just fast scrolling nonsense, so Something works with the chip.

any ideas guys?

Hi.
Please can you eMail me your VHDL (eMail address can be found on the link at the bottom of the web page) and I'll check it on mine and get back to you.

Several others have built it so the wiring on the page should be fine.

Regards.

Grant.

Hi YT2095.

I have replied to your issue via eMail. There was an error in your top level VHDL (and need to check the display VHDL changes as it shouldn't have compiled OK). With the fix it all works fine for me.

Regards.

Grant

Thanks!

I made that code change and indeed the Screen is now in 80 mode and looks Much better.
I did actually send you the wrong file(s) though, but it doesn`t make much difference as both have the "Memory Size" problem, it`s just that One is the RAM only mod.
Everything compiled just fine after making that change, but I still have that problem?

it all works well until I press C, and then the "Memory size" prompt gets spelled out letter at a time, and then when I press Enter, the cursor drops to the next line, vanishes and it just hangs from there on in.
the same happens if I enter a value such as 8192 for example.

the fact that it`s working at all, and even in the higher res, would suggest that the RAM is wired up correctly (or at least for the address areas used), so this has really got me beat!

Hi.
I'll see if I can eMail you later a zip of the complete project that is working on mine (80 column, extended RAM) so that you can double-check if there is a VHDL issue somewhere. I'll use the published code and changes on my page.

Very odd because it is OK for myself and others.

Anyway, try the project files that I will send and let me know.

Regards.

Grant

Hi YT2095.
I have eMailed you the complete set of files (as uploaded), updated with the changes to use external RAM and also 80 columns.

Please let me know how you get on - definitely works for me (and others).

Regards.

Grant

Hi YT2095.
As Grant knows I've tried many configurations of the UK101 and the "pick and mix" and they all work well. I've built a good few home made projects like this and when it doesn't work it has allways been my fault. It's amazing how many times I can check something only to find the fault is right in front of me. This might be obvious but check that power is on the ram chip by continuity not voltage. Check that there is no short on side by side pins. If you have a scope check that the address and data lines are toggling. The higher end address lines sometimes are stable if there is a crash but usually toggle on a reset. It's normal for data lines to look "dirty" but address lines usually look clean. I remember fault finding on a board with CMOS logic. It would work for hours then fail. I tried changing chips still the same. It turned out to be no power connected to a logic chip. The chip was effectivly self powering as long as the logic had some highs. Keep all lines as short as possible. My very last option would be component replacement. Its allways usefull if you have something to test the ram chip on. Good luck I'm sure you will get it working if you persevere.

Graeme

Well, this is sort of embarrassing really.
Turns out it wasn`t the code or any mistake there (apart from that one line mentioned above), but rather a Hardware problem.
the New code you sent also did exactly the same thing too.
here`s my incarnation of the same circuit:

http://s1130.photobucket.com/user/YT209 ... sort=3&o=0

after Much rechecking of the wiring it still is wired up perfectly, no shorts either, About ready to nailgun it to the wall, I thought I`d check the track side with the magnifying glass just in case my wife was right and I do need glasses.
I use a Drill bit to cut the tracks (always have done), but This time some weren`t totally cut (about 5 in total), making each one a little Antenna of sorts that ran the full length of the board, and some even side by side.
after I corrected that, it fired up 1`st time and worked perfectly.

needless to say we`r booked in next week at the opticians!

Thanks for all your help!

Brill.
Glad it's working for you

All the best.

Grant

Hi.
[Already posted this message elsewhere, but including it here in case you didn't know]

I have given up with the existing web hosting - they banned me because they said I was getting too many hits and instead of throttling as they used to, they now just say I violated their T&Cs and take me down !!
So, I have now purchased my own domain (searle.wales) and put my files on a different hosting server.
Since I now have my own domain I can then put my files anywhere and move them if needed without affecting any posts such as this.

I may move some folders around a bit, so please always go to the starting page (http://searle.wales or http://www.searle.wales) and you will always get to me wherever I have moved to.

My pledge is to keep my pages online (since 1997!) so if they go offline for any reason don't worry - they will be back.

Have fun!

Grant

Thanks for keeping it alive.
A valuable resource like no other.

Indeed! I was missing it; thanks for putting it online again.