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Posted By

crock
on 2016-04-10
06:35:44

Who has a broken 1551?

I asked the question on the c16/+4 FB page but didn't get any response. Does anyone here have broken 1551's?

I have two, which are failed due to the 6523T in the paddle or the 6525 in the drive, causing 'DEVICE NOT PRESENT' errors when trying to access it. These chips are virtually impossible to obtain, but their functionality is fairly easy to reproduce so Jim Brain is prototyping a replacement if there's sufficient interest?

Posted By

siz
on 2016-04-10
10:38:46

Re: Who has a broken 1551?

Fortunately both of my 1551s are fully working.

There is a project from our BSz who created a "1551-II", a modified 1541-II drive which can be switched to 1551 mode. BSz created his own TCBM bus implementation without the actual 6525 and 6523T ICs.
You can read about his project in his blog here: http://hup.hu/node/120659 and here: http://hup.hu/node/121506. (Unfortunately it's in Hungarian but perhaps worth checking anyway)

Posted By

Patrick
on 2016-04-10
12:43:06

Re: Who has a broken 1551?

I have a broken 1551 drive and i don't know what is wrong. If you have something that will fix it, i'm in!

Posted By

George
on 2016-04-11
04:24:22

Re: Who has a broken 1551?

I have a broken one too. It would be nice to restore it. But i use a sd2iec.

Posted By

Chicken
on 2016-04-11
11:36:55

Re: Who has a broken 1551?

If the price is reasonable, count me in. Not just to support the project but because it's usually the "unfixable" (lack of replacement parts) issue with 1551 drives.

Btw, forum64 might be a good place to get more feedback. Most 1551 drives have been sold in Germany and there are a couple of users on that forum who might have a 1551 but neither follow this forum nor that FB page.

siz: BSZ'S project was featured here, too. I remember being absolutely amazed =) I always wondered if this would ever go beyond "prototype" or "one of a kind", i. e. if he would offer to sell this. Could you ask him about that? Even with sd2iec around, there are still some people who like real disk drives.
I know, this is definitely more complicated than the SIDCARD due to the changes in the drive and in the plus/4. Nevertheless, if he could roughly estimate how many boards he would have to make (that is "sell") for what price and which modifications the user would have to perform himself, that would be great.

Posted By

MMS
on 2016-04-12
15:36:49

Re: Who has a broken 1551?

wow, that project... I went through the page, and I dropped my jaw.
Well, I think in the last 2 years I spent 1/10 of the effort to the RS232 mouse project he put in that 1551 hacking... Respect.

OFF
(BTW, anyone is in to do a optimize a RS232 mouse driver? Maybe a competition?

The HW part is definitely ready, the documentation in 50-60%, but I am struggling to compress the resident driver made by BSZGG (good for some BASIC prg testing) into the space available on zero page, just to speed things up and do not disturb programs).
The code is 327 bytes long, and the longest available free space is 191 bytes (tape buffer) and 141 bytes is in the Speech area. I know, if you add them together, then almost there (and the Y coordinates also use 2 bytes, though 1 would be is enough), but hell, I do not want to load the driver in two parts.

)

CORR: if the resident driver is on zero page and the the X, Y coordinates stored there too (not at $5000), then 54 bytes could be saved VS original size, but still the code 274 bytes long.

Posted By

crock
on 2016-04-13
01:41:05

Re: Who has a broken 1551?

Thanks for the feedback gents.

Patrick, George - I wrote a small basic program to test the 1551 cartridge paddle if you want to try it. It checks that the registers in the 6523T can be read and written to at the correct locations. Then, when the DDR's are set as inputs, that they are being pulled up by the drive when powered on.

http://inchocks.co.uk/commodore/1551/1551test.prg

This should be good enough to determine that the PLA and the 6523T are in good working order. Feedback welcome.

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