48k Atari 400 upgrades available

[Jeffrey Worley]

I'm launching a small project to make 48k boards for the 400.  The build is not trivial, so my work will make your work a heck of a lot easier.  I am modifying the ram boards for you, which is more than 9/10ths of the work.  The work remaining for you is to run four short wires on the bottom of your 400's motherboard, easily removed to return the machine to stock configuration.  I will let the boards go for $75.00 each with the trade-in of your 16k board, or, you can remove your 16k board and send it to me and I will modify it.  Anyone with basic soldering skills and a screwdriver can make the necessary wire runs on the motherboard.

 

The modification I'm following is the Crowell/Davies version, as it is the simplest for the user to install, being entirely confined to a plug-in ram board modification but for the four wires on the motherboard, which run from the cartridge port to the ram slot on the bottom of the motherboard.  The boards have either 64k or 256k of dram onboard, of which 48k is addressable as stock, Atari memory, just like the 800 fully-loaded.  The pictured on is using 256k drams, as I have more of them and they are all new. 

 

Please contact me if you would like one of these and I'll earmark one for you.  I have a limited number of ram cards of my own to modify, so your trade-ins are really necessary to keep the boards coming.

 

Best,

 

Jeff

[Paul Westphal]

FYI - The UNO Cart - WILL WORK - on Atari 400's that are upgraded with the official Atari 48k kit. I have tested this on 4 machines. It would be cool if yours did as well.

 

Paul

[Jeffrey Worley]

6 hours ago, Paul Westphal said:

FYI - The UNO Cart - WILL WORK - on Atari 400's that are upgraded with the official Atari 48k kit. I have tested this on 4 machines. It would be cool if yours did as well.

 

Paul

I'd be surprised if it didn't.  It works just like a 48k 800.

 

The Side2 also works on the 48k 400, as does Spartados X and any other warez that will work on a fully-loaded 800.  The only thing the 400 is lacking to be a full-blown 800 is the memory, which this board provides.

 

As with the 800 with 48k the 48k 400 can use Spartados X in the Side2, but there is not enough memory on either machine to load the Side.sys driver, so for these machines, SIO-based hard disks are the way to go.  The Side Loader however DOES work peachy with the onboard CF/SD card so you can load games and software out of the CF slot no problem, it is only using the CF slot as a hard disk in DOS that is any issue.

 

Best,

 

Jeff

[BillC]

1 hour ago, Jeffrey Worley said:

The only thing the 400 is lacking to be a full-blown 800 is the memory

Also missing the rarely used right cartridge slot and, more important, the DIN5 monitor port.

[StickJock]

And not to overlook the obvious... the keyboard!  ?

 

Starting to sound like a Monty Python skit!

No one expects the Spanish Inquisition!

Our chief weapon is surprise, fear and surprise; two chief weapons, fear, surprise, and ruthless efficiency! Er, among our chief weapons are: fear, surprise, ruthless efficiency, and near fanatical devotion to the Pope!

Um, I'll come in again...

[+DrVenkman]

Regarding the UNO Cart in a 48K 400 or a stock 48K 800 ... from testing my own UNO in two of my own machines, the UNO Menu loads up but the SD card contents do not appear. So "works" is a pretty tenuous thing in my personal experience. To be fair, my 48K 400 was done by a prior owner decades ago using what appears to be a version of the Claus B. mod. The 800 I tested it with was dead-stock. You mileage may vary. 

[BillC]

There were a couple of aftermarket 400 keyboards available as well as the AKI(Atari Keyboard Interface) BITD, I also modified a 1200XL keyboard to connect externally to a 400 as well. These days the TK-II is available to connect a PS2 keyboard.

[ClausB]

The Uno cart problem might be due to the pull down resistors on the RAM deselect lines. On the 800 they are 680 Ohm where on the XLs they are 1K. IIRC replacing those fixes the problem.

[Jeffrey Worley]

7 hours ago, ClausB said:

The Uno cart problem might be due to the pull down resistors on the RAM deselect lines. On the 800 they are 680 Ohm where on the XLs they are 1K. IIRC replacing those fixes the problem.

Could this be why I have a couple of 800's that do not see the CF slot on the Side2.  SDX boots up and the side.sys loader loads (800 with 512k upgrade), everything is fine, but "No Media".  Same with a different 800 with 48k.  Side.sys can't load of course, but in Side loader mode it should see media and does not.  The rest of my 800's all see the card in Side Loader mode, and if I throw a ram upgrade in them, SDX can see them too.

 

Best,

 

Jeff

[Faicuai]

13 hours ago, BillC said:

Also missing the rarely used right cartridge slot and, more important, the DIN5 monitor port.

Well, more realistically, the list of items missing on the 400:

 

1. Right-cart port.

2. Personality Card-slot (and presumably dual floating-buses present on the 800 with it?)

3. RAM-expansion slots.

4. Special Slot/3 slot with support for I/O-driven expansions (e.g. BITD 80-col cards, etc,)

5. Power-board with Y/C, Composite video interfaces and sound...

 

But even with the above list, the little 400 seems to have PHI2 enabled on pin-S of its cart-port whereas the 800 has RASTIME, instead, reason for which some things do not work on the 800 as they are supposed to...

 

[Faicuai]

48 minutes ago, Jeffrey Worley said:

Could this be why I have a couple of 800's that do not see the CF slot on the Side2.  SDX boots up and the side.sys loader loads (800 with 512k upgrade), everything is fine, but "No Media".  Same with a different 800 with 48k.  Side.sys can't load of course, but in Side loader mode it should see media and does not.  The rest of my 800's all see the card in Side Loader mode, and if I throw a ram upgrade in them, SDX can see them too.

 

Best,

 

Jeff

That or... RASTIME instead of PHI2 on pin-S of 800's cart port?

 

I have the exact same same issue on my 800-test bed with SIDE2... but not at all on my Incognito production unit... but I never replaced RASTIME on the latter... just a couple of resistors during Incognito's install...

 

...And on other stock 800s that I have tested, SIDE-2 has worked well (!?)

 

[Jeffrey Worley]

14 hours ago, BillC said:

Also missing the rarely used right cartridge slot and, more important, the DIN5 monitor port.

And a partridge in a a pear tree..... :-)

[Jeffrey Worley]

3 hours ago, Faicuai said:

That or... RASTIME instead of PHI2 on pin-S of 800's cart port?

 

I have the exact same same issue on my 800-test bed with SIDE2... but not at all on my Incognito production unit... but I never replaced RASTIME on the latter... just a couple of resistors during Incognito's install...

 

...And on other stock 800s that I have tested, SIDE-2 has worked well (!?)

 

Here''s the fix:  You need to cut rastime and insert phi2 on the left cart slot.  Funny, but I must have had 800's that had this done at the factory or otherwise, as it is only recently I noticed this problem.  Just found and did this fix and -- boomshakalaka!

 

NOTE! NOTE! NOTE!

 

The picture below appears to have an arrow pointing to a trace to cut.  This is not the trace to cut.  The trace the arrow indicating to cut is the trace the ARROW IS CUTTING (overlaying).  So, the yellow arrow is NOT AN ARROW.  It is a yellow slice this trace mark.

 

<SNIP>

 

"Then connect pin "A" and pin "S" on the "right" cartridge slot together as shown with the yellow wire. Then cut the RAS trace at the location marked on the right."

 

 

<SNIP>

 

https://www.wudsn.com/index.php/productions-atari800/tools/thecart/atari-800-fix

 

Best,

 

Jeff

Edited July 4, 2020 by Jeffrey Worley
Clarity

[Faicuai]

31 minutes ago, Jeffrey Worley said:

Here''s the fix:  You need to cut rastime and insert phi2 on the left cart slot.  Funny, but I must have had 800's that had this done at the factory or otherwise, as it is only recently I noticed this problem.  Just found and did this fix and -- boomshakalaka!

 

NOTE! NOTE! NOTE!

 

The picture below appears to have an arrow pointing to a trace to cut.  This is not the trace to cut.  The trace the arrow indicating to cut is the trace the ARROW IS CUTTING (overlaying).  So, the yellow arrow is NOT AN ARROW.  It is a yellow slice this trace mark.

 

<SNIP>

 

"Then connect pin "A" and pin "S" on the "right" cartridge slot together as shown with the yellow wire. Then cut the RAS trace at the location marked on the right."

 

 

<SNIP>

 

https://www.wudsn.com/index.php/productions-atari800/tools/thecart/atari-800-fix

 

Best,

 

Jeff

What I could never figure out is WHY, in principle. Atari engineers decided to provision RASTIME on both cart-ports, and PHI2 only on the right-one...'

 

I do agree I can't either explain why some of the 800s I have tested work well with my SIDE/1 and SIDE/2 carts, and others don't... I have to bring Pin-S on left-cart under the ScopeMeter, and see what the hell is going on (between these MoBos...)

[_The Doctor__]

Dual floating bus was great, now imagine separate antic access on top of this with it's own memory, utilize the rom/ram/os bit to flip up to antic's own ram ! ah where things were going... but didn't...

[Faicuai]

15 hours ago, ClausB said:

The Uno cart problem might be due to the pull down resistors on the RAM deselect lines. On the 800 they are 680 Ohm where on the XLs they are 1K. IIRC replacing those fixes the problem.

Very interesting.

 

If you refer to resistors for RD4 and RD5 lines of Left-cart port, well, lo-and-behold those were precisely the ones I replaced with 1200+ Ohms ones during Incognito install... And on that unit, SIDE 1/2 works like a charm (with stock RASTIME provisioned on pin S, instead of alternate PHI2...)

 

If that if the case, I would strongly suggest proceeding with such replacement first (which will pave they way for a future Incognito install anyway), besides being fully reversible at any time we wish, as opposed to PHI2-mod is NOT, which is essentially a one-way ticket once that trace is cut...