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1450 XLD motherboard build, assorted questions


Vandal968

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There might not be a HATABS handler. Interfacing the disk drive is a "physical layer" type of thing, whilst the DOS file handler is a "logical layer" type of thing.

 

In the same manner, IDE Plus 2 can be used that way - disabling the onboard SparaDos means that effectively you're supplying the DOS and the expansion device itself is just supplying the physical layer.

 

My guess is that the disk controller would either map to page $D1 automatically when it's PBI ID is enabled via $D1FF, or to either $D6/$D7 when activated, or could even be always present at $D6/$D7.

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Well, the handler ROM/Eprom does have a HATABS handler for the V: and T: devices and maps to the $D6xx area for the PBI, so I'll be able to exclude that part of the code and the rest should be for the floppy board interface...

 

One thing I'd like to do is change the Device ID of the floppy handler from Zero(0) to something else so I can also use the IDE Plus 2 on this :)

I'll look for a page $D1 reference in the code...

 

Jay

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I've read that the pbi disk drives on tghe 1450xld were problematic, although it would be great to actually have one!

 

Yep, I agree... If I can find the schematic of the prototype, I could use that as a starting point to make an interface that works :)

 

@Rybags

Looking further into the handler code last night, I found a few calls to the D1xx area. Time to read up on the PBI docs...

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  • 8 months later...
  • 2 months later...

Damn, and I was just thinking a few days ago to ask the guys who only posted partially completed pics of their build, if they wanted to sell theirs...

I have enough parts to build a second as I bought doubles of most everything from Digi-Key ;)

 

I'll wait and see if someone else posts one on eBay...

 

@Stephen, Way to go :thumbsup: :thumbsup: :thumbsup: and take your time building yours :) I took a month to build mine up, desoldering parts from a donor 1200xl and 800xl, cleaning leads, forming leads with the bend at the right position, etc...

 

There were two parts that Digi-key didn't have that Vandal968 posted in the parts list, but found a different part# to use. One was the relay for the modem and the other I forget at the moment. I have the extra parts still in their bag, so if you need part numbers, let me know :)

 

Jay

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I just made my orders from Digikey and Mouser (I had most of the chips from Best ages ago, when I first contemplated doing this). I made a start on my board (before vandal came up with his corrected and verified BOM), but got side tracked with real life, but now that we've got everything we need to do this properly, I'm hoping to get going on it again and have another working 1450 board someday soon.

 

I have a question:

zero ohm resister - this is basically just a wire isn't it?

 

EDIT: answered my own question... it's basically just a wire, but often in the form of a resister to allow automated board assembly. Can you buy these at Digikey?

Edited by Shawn Jefferson
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Digikey should have them, I used some from my donor 1200xl and 800xl, plus bought some extras at a local surplus store.

I'd use the zero ohm resistors instead of a wire for safety sake.

 

There are 8 RF / Ferrite beads used that I also took from the donor xl's...

 

Edit, searched Digikey and they do :)

http://www.digikey.com/product-detail/en/ZOR-25-B-52-0R/0.0QBK-ND/18794

Edited by AtariGeezer
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I was able to buy two of them (can't remember off the top of my head, but probably the same two that the OP bought as well), so I would need one of them burned for sure. I bought all the chips I needed from Best along with the schematics years ago... just didn't progress nearly as far as Vandal did. I'm hoping to get this thing built in the next couple of months.

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U11 (PAL-C) [PAL16R4] is the one that you probably need, the JED is posted in this thread.

One of the members here was kind enough to program a few of those for me. Later on I programmed a GAL to try with this program. paltogal.zip

 

Remember that the schematic that you bought isn't 100% correct. The voltage lines are swapped on one page and you need to swap 2 transistors on that same page...

 

I think I spent 2 weeks alone on just verifying the schematics :)

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I'm going by the BOM that Vandal posted. That should be enough to build the board out, right? It is the PAL16R4, I just received the chips in the mail today, so I will at some point need to get those burned. I may have the equipment to do that myself, need to double check.

 

I'm still missing the modem chip... will need to source that still. Might have to check ebay.

Edited by Shawn Jefferson
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Yep, the BOM is accurate for the most part, it does show the Q3 and Q8 reversal, but I'm not certain as to R141 as it gets quite hot. The 1400 schematics shows it as a 1K ohm, in vandals BOM he's using a 100 ohm. It also doesn't have a comment about the power rails coming from power plug being wrong on the printed schematic...

 

There are modem chips (74HC942) on ebay: http://rover.ebay.com/rover/1/711-53200-19255-0/1?icep_ff3=9&pub=5574883395&toolid=10001&campid=5336500554&customid=&icep_uq=74HC942&icep_sellerId=&icep_ex_kw=&icep_sortBy=12&icep_catId=&icep_minPrice=&icep_maxPrice=&ipn=psmain&icep_vectorid=229466&kwid=902099&mtid=824&kw=lg

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LOL - I also ordered one in case I ever get a board to populate. I never thought I would be buying a 300 baud modem in late 2012 :)

 

Isn't your board on the way yet? or is Bryan on the fence about letting his go?

 

I've bought a few 300 baud modems in the past 2 years; XM301's, 830's, 835's and a 1030 ;)

Probably will never use them, but they are nice to look at :)

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I also have a 1030 - I was horrified to see them being turned into cases for the SIO2SD, so I bought one a save it. I distinctly remember the first time I went online. It was 1987, and I was at my buddy's house (from whom I "borrowed" all of my games). He had a 1200XL, 1050, and 1030 modem at the time I just had a 400 and a 410. Good times :)

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Isn't your board on the way yet? or is Bryan on the fence about letting his go?

 

I've bought a few 300 baud modems in the past 2 years; XM301's, 830's, 835's and a 1030 ;)

Probably will never use them, but they are nice to look at :)

Yep, it's funny what we'll go and buy for a complete collection! I don't even remember what we actually used as a modem in the '80s, but I know it wasn't one of the Atari ones! I've got an 830, 1030, XM301 and SX212 now. Still looking for an 835, though ironically, I have Telelink I and II without having the 835.

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I also have a 1030 - I was horrified to see them being turned into cases for the SIO2SD, so I bought one a save it. I distinctly remember the first time I went online. It was 1987, and I was at my buddy's house (from whom I "borrowed" all of my games). He had a 1200XL, 1050, and 1030 modem at the time I just had a 400 and a 410. Good times :)

 

That's cool, I plan on keeping mine original too. When I was on Guam, a teacher that was in our user group had one, Thought they were pretty slick. I had a MPP 1000-C at the time. My first trans-continental dial-up connection went through a Sat-Link and the echo was terrible, sometimes I got lucky and got the underwater cable connection. It took 2 or 3 nights to connect to the S.P.A.C.E. BBS to download the AMIS BBS package so we could have an Atari Based BBS on the island. There was even a mention of it in A.N.A.L.O.G.'s "So you want to be a SysOp" article where they said "we even had calls as far away as Guam" :)

 

Yep, it's funny what we'll go and buy for a complete collection! I don't even remember what we actually used as a modem in the '80s, but I know it wasn't one of the Atari ones! I've got an 830, 1030, XM301 and SX212 now. Still looking for an 835, though ironically, I have Telelink I and II without having the 835.

 

LOL, yup... I forgot about the SX212's, have two of those too and even a Pocket Modem :)

From the 3 835's I have, 1 works and another is missing a case. Bought some parts to repair the 2 bad ones, but haven't gotten around to them yet...

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