Wanted: ICD RAMBO XL Schematic

[TZJB]

15 hours ago, ClausB said:

https://forums.atariage.com/topic/259893-atari-dos-20-disk-drives/?do=findComment&comment=4679021

Thanks Claus. This explains it perfectly.

14 hours ago, kheller2 said:

Under DOS 2.5 there is a setup/configuration utility you can run that will configured the amount of drives/buffers and ram disks.

Thanks. I normally use MyDOS or Sparta but as they already have good RAMdisk handlers I thought that I would try DOS2. It looks like I need to POKE 1802 with 15 for four drives to work and explains the Error 160 that I received.

[TZJB]

On 10/25/2022 at 6:22 PM, ClausB said:

It patches whatever OS is in ROM after copying it to the underlying RAM. It overwrites the international character set at CC00.

Hi @ClausB, just to confirm that your RAMdisk QMEGXLS4.OBJ is now working in my 800XL RamboXL with OS rev.2 - the original 800XL OS ROM,  and OS rev.4 - the XEGS OS ROM, together with DOS 2.0s or DOS 2.5 configured for 4 drives. @kheller2 is correct as DOS 2.5 has a SETUP.COM to do this configuration whereas DOS 2.0s needs to have a POKE 1802,15 in BASIC and saved back to the disk. The DOS 2.5 RAMDISK.COM has to be renamed to stop it loading otherwise QMEGXLS4.OBJ freezes up rather than over-write RAMDISK.COM. Thanks for your help in this matter.

[hueyjones70]

I have a 1200xl that has been modified to have the 800XL OS ROM and internal BASIC. If I install the RAMBO, do I follow the 1200XL instructions or the 800XL instructions?

[+kheller2]

14 minutes ago, hueyjones70 said:

I have a 1200xl that has been modified to have the 800XL OS ROM and internal BASIC. If I install the RAMBO, do I follow the 1200XL instructions or the 800XL instructions?

I believe you follow the 1200XL. The OS doesn't play role, the version of Antic and the memory decoder does.  But a picture would be helpful showing the differences.  RAMBO needs access to A7 which has to be done differently on the 1200XL (on the 800XL RAMBO picks this up directly from replacing the LS158, the 1200XL has this on another LS158).

[+kheller2]

On 6/9/2022 at 7:00 PM, mytek said:

RAMBO XL-II Ready for Production

 

Assembled Board TOP (I used HCT chips, but the original 74LS chips can be used as well)

 

Assembled Board BOTTOM

 

Installed in 1200XL with Sophia Rev C

 

 

Buy Bare PCB from OSH Park (minimum order of 3 pieces for $16.75, which includes free international shipping)

 

 

Buy LINK

Schematic: RAMBO_XL-II_V1.1_schema.pdf

Gerbers: RAMBO_XL-II_gerbers.zip

Manual: RamboXLManual.pdf

 

Sorry no BOM, but between the PCB silkscreen and the schematic it should be pretty easy to figure out what is needed.

 

Here's a LINK to the double pin header strip used for piggybacking.

 

 

@mytek  Is version 1.1 the latest/correct schematic?  I'm a bit tired tonight, but noticed it says it plugs into U7 for the 1200XL, don't you mean U10?  And for J1, why would PIN13(U10)- A13 be fed into U7's lifted pin 3? That would make A0 and A13 fed to RA0. There is probably some overlapping decoding going on that I'm just not sussing. 

 

[+mytek]

3 hours ago, kheller2 said:

@mytek  Is version 1.1 the latest/correct schematic?  I'm a bit tired tonight, but noticed it says it plugs into U7 for the 1200XL, don't you mean U10?  And for J1, why would PIN13(U10)- A13 be fed into U7's lifted pin 3? That would make A0 and A13 fed to RA0. There is probably some overlapping decoding going on that I'm just not sussing.

You are correct on it being U10 for the 1200XL.

 

 

And yes it appears that my schematic called it out incorrectly as U7, with Version 1.1 being the last schematic version.

 

Best to reference the ICD manual since this board is a clone of theirs: RamboXLManual.pdf

 

I never put this project on my AtariBits website, and perhaps never will since it was really just something I made for my own use. I figured sharing it here on AtariAge was probably sufficient for anyone that wanted to build one themselves. There were bound to be a few typos in in the docs I whipped up.

 

EDIT: Your link also had a good picture of my 1200XL install that does a very good job of showing what goes where. Here's a copy of it for those that possibly missed it...

[Dopeyman06]

@mytek

 

Just to confirm in creating one of these boards, I would need everything that's listed in your BOM? As for R1, I read a little further down this topic and you confirmed that it requires a 33Ω resister that @x=usr(1536) asked. But which one of these 2 is the correct one?  690507 or 661141?

 

Also, I would need 2 of these 74LS158 chips, correct?

 

And to put everything into my 800XL, I would go through ICD's RamboXL manual, right?

 

Edited May 20, 2023 by Dopeyman06

[Beeblebrox]

@Dopeyman06

 

FYI there is a slimmer version available with SMD equivilent Chips and discussions for an even smaller pcb, all here:

 

Also don't make the mistake I made and naively try to install one in and 800XLF, (an 800XL with a Freddie chip), as not compatible.

 

For Mytek's current design pcb below here is the BOM and a few images of an install:

 

 

C1 is a 100nf (0.1uf) ceramic axial capacitor

R1 is a 33ohm 1/4w 5% carbon film resistor (where I think you can use 1/8w as well)

 

You'll need to socket the 800XL's 74LS158 (U27) chip for the Rambo XL board to plug into.

 

The top connector headers are all 2.54mm pitch right angle ones

The main header strip connector is 2.54mm Pitch Male to male Pin Header Connector (where depending on whether you have round socket or a dual wipe socket for the 158 chip on your 800XL board you'll need to get the right one to fit).

 

Instead of LS logic chips I believe you can use HCT equivilents.

 

Remember to get the little jumpers for the j2 and j3 headers also.

 

Plus you'll need to socket the 800XL's 74LS158 (U27) chip for the Rambo XL board to plug into.

 

Here's how it all connects, taken from here:https://www.ebay.co.uk/itm/266062316837 among other sources

 

 

 

 

 

Edited May 20, 2023 by Beeblebrox

[+x=usr(1536)]

4 hours ago, Dopeyman06 said:

I read a little further down this topic and you confirmed that it requires a 33Ω resister that @x=usr(1536) asked. But which one of these 2 is the correct one?  690507 or 661141?

690507.

4 hours ago, Beeblebrox said:

R1 is a 33ohm 1/4w 5% carbon film resistor (where I think you can use 1/8w as well)

Just confirming that I used the 1/4W resistor and had no issues.

[Beeblebrox]

@x=usr(1536) just out of interest did you source LS versions of the chips or did you use HCT versions? 

[TZJB]

4 hours ago, Dopeyman06 said:

Also, I would need 2 of these 74LS158 chips, correct?

 

You would only need one as the removed U27 74LS158 can be reused in the RamboXL.

[+x=usr(1536)]

2 minutes ago, Beeblebrox said:

@x=usr(1536) just out of interest did you source LS versions of the chips or did you use HCT versions? 

LS versions.  Since they were what was specced originally, I figured that it was probably worth sticking with them.

 

Not opposed to the HCTs by any means, but working to the baseline before trying tweaks seemed like the best approach.

[Beeblebrox]

28 minutes ago, x=usr(1536) said:

LS versions.  Since they were what was specced originally, I figured that it was probably worth sticking with them.

 

Not opposed to the HCTs by any means, but working to the baseline before trying tweaks seemed like the best approach.

Sure. Makes sense. I struggled to find LS versions. Aside having ls158s handy, the hct versions were the only ones I could find for the 153, 139 and 393 chips. In the end I went with hct versions across the board rather than mix them up.

Edited May 20, 2023 by Beeblebrox

[reifsnyderb]

When it comes to using LS chips, F chips, HCT chips, etc., if there isn't aren't any timing issues to worry about, I just go with whatever is cheaper.  Many times the F chips are cheaper.

[+mytek]

7 hours ago, Beeblebrox said:

Instead of LS logic chips I believe you can use HCT equivilents.

 

36 minutes ago, reifsnyderb said:

When it comes to using LS chips, F chips, HCT chips, etc., if there isn't aren't any timing issues to worry about, I just go with whatever is cheaper.  Many times the F chips are cheaper.

I had issues on a 1200XL install when I used HCT instead of the LS chips as designated on the silk screen, and they were both TI branded chips. I didn't delve too deeply into the reason why, because the LS equivalents are still easily gotten (Jameco, Digi-Key, Mouser and of course eBay are all viable sources). The savings in power that HCT would bring in this case is not an issue for so few chips.

 

Somewhere in this thread the explanation of what happened with HCT chips is mentioned. I just don't recall exactly what the deal was, but I do believe it would only affect certain applications.

 

Found it...

 

The game mentioned that was having problem might be the only one. So for those that have used HCT chips it doesn't look like a deal breaker.

[Dopeyman06]

12 hours ago, x=usr(1536) said:

690507.

Just confirming that I used the 1/4W resistor and had no issues.

Thank you for the confirmation 

[_The Doctor__]

playing it safe stick with 74F

[Dopeyman06]

Another couple of questions...  Would these be the RAM CHIPS that would replace the 64k RAM chips?

 

Also, I placed a PCB order from JLCPCP. Their minimum order is for 5 boards. So can someone confirm that I have all the right components to fill all 5 boards?

 

Greatly appreciated!!

 

Edited May 29, 2023 by Dopeyman06

[TZJB]

3 hours ago, Dopeyman06 said:

Another couple of questions...  Would these be the RAM CHIPS that would replace the 64k RAM chips?

 

Also, I placed a PCB order from JLCPCP. Their minimum order is for 5 boards. So can someone confirm that I have all the right components to fill all 5 boards?

 

Greatly appreciated!!

 

 

The DRAM chips that you linked to seem okay but they are not brand specific. From the alternatives available, the Vishay 41256 cost slightly less and are faster, the NEC 41256 cost slightly more. I would be tempted to choose the NEC 41256.

 

Looking at the other parts, you probably need a bent 3 pin header which you can make from the 26 pin headers. You probably don't need 5 of them either. You only need one 40 piece 30cm jumper wire as you only require 25 pieces for 5 boards. You can put the money saved towards extra 74LS158, as the use of the existing 74LS158 isn't mandatory, and you may want both 74LS158 to look the same. It's good to have a spare. The rest look to be correct.

Edited May 29, 2023 by TZJB

[Dopeyman06]

18 hours ago, TZJB said:

 

The DRAM chips that you linked to seem okay but they are not brand specific. From the alternatives available, the Vishay 41256 cost slightly less and are faster, the NEC 41256 cost slightly more. I would be tempted to choose the NEC 41256.

 

Looking at the other parts, you probably need a bent 3 pin header which you can make from the 26 pin headers. You probably don't need 5 of them either. You only need one 40 piece 30cm jumper wire as you only require 25 pieces for 5 boards. You can put the money saved towards extra 74LS158, as the use of the existing 74LS158 isn't mandatory, and you may want both 74LS158 to look the same. It's good to have a spare. The rest look to be correct.

Thank you very much for this confirmation and advice!!!

 

[Dopeyman06]

Hello again. Another confirmation please. 

 

Will these 256k chips work with the Rambo?

 

[TZJB]

I can't find a datasheet for the Mostek MK4128. The others all seem to have the correct specs for 256Kb 1 bit DRAM.

[Dopeyman06]

6 minutes ago, TZJB said:

I can't find a datasheet for the Mostek MK4128. The others all seem to have the correct specs for 256Kb 1 bit DRAM.

I was leaning towards the same conclusion. Thank you for the confirmation. 

 

Also, I'm thinking (because of the label) that the Mostek chips are 128k and not 256k.  

[TZJB]

2 hours ago, Dopeyman06 said:

I was leaning towards the same conclusion. Thank you for the confirmation. 

 

Also, I'm thinking (because of the label) that the Mostek chips are 128k and not 256k.  

From what I can gather without the datasheet, the MK4128 is 2x 4164 in one chip.

[ClausB]

Or perhaps the 4128 is a 41256 with bad bits on one half, so only 128Kb are useful. This was common practice in early days of new DRAM chips, when yields were low.