1064 replacement possible?

[Mazzspeed]

The guy I bought my 600XL off offered me a 1064 for $200.00 AU.

 

I turned him down as I planned on an internal 64k upgrade all along. I could have bought it and flipped it for some good $$, but I don't believe in that.

 

Hopefully someone picked up a great bargain and is enjoying it.

[+kheller2]

On 6/13/2021 at 8:27 PM, bob1200xl said:

Wouldn't a 1064 do what you need? Are there problems with just using a 1064?

 

I am guessing that the 1064 just kills the 16K chips and slides in 64K.

 

Bob

 

While the 1064 does have 64k, the upper 48 are mapped and the internal 16 still used.  That’s the funkyness of that LS32 chip on the 600.  The 1064 also has one. I’m not sure why they just didn’t kill the onboard  unless that isn’t possible with that chip. 

[+tf_hh]

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

What I'm wondering is if it might be possible to have something similar to @tf_hh's 576K upgrade, but connected to the PBI slot.  In all use cases, it would disable internal RAM regardless of size and provide 64K of base memory with 512K of extended RAM that could be paged in and out as necessary.  This way, there's only a single device needed for external RAM upgrades.  Should help with pricing as well as compatibility.

 

When there´s some demand, it´s no problem the create an external version of the 576 KB expansion for a good price. But Steve has to make the case

 

[+DrVenkman]

17 minutes ago, tf_hh said:

 

When there´s some demand, it´s no problem the create an external version of the 576 KB expansion for a good price. But Steve has to make the case

 

Paging @Mr Robot …  

[+ZuluGula]

I personally would prefer Hammond case instead of 3D printed one.

https://www.hawkusa.com/manufacturers/hammond-mfg/enclosures/plastic-enclosure-box/1551lbk?gclid=EAIaIQobChMIib3VwI-a8QIVm3NvBB0YhwEZEAQYAiABEgKFYfD_BwE

Like one used in @ctirad RAM320XL.

 

[+mytek]

4 hours ago, ZuluGula said:

I personally would prefer Hammond case instead of 3D printed one.

https://www.hawkusa.com/manufacturers/hammond-mfg/enclosures/plastic-enclosure-box/1551lbk?gclid=EAIaIQobChMIib3VwI-a8QIVm3NvBB0YhwEZEAQYAiABEgKFYfD_BwE

Like one used in @ctirad RAM320XL.

 

Not too sure I like the looks of the cut-out hole and the intrusion on one of the mounting securing screws .  This is usually the problem with that approach, especially for the less mechanically inclined, thus making a 3D printed version much better for the masses.

[Mathy]

Hello x=usr(1536)

 

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

I understand the points that you're raising here.  However, there's something I'm not totally clear on:

If I'm following correctly, what you would like is a PBI-attached 64K memory expansion with PBI passthrough - like a 1064, but in a smaller form factor.  From there, subsequent memory upgrades could be attached to the PBI port of that device to expand beyond the stock 64K.  Is this correct?

 

Yes

 

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

Tell me if this sounds correct: what you are essentially describing is a 64K 'shim' upgrade that would sit between the 600XL and a Universal memory upgrade offering considerably more memory that would work on an 800XL (or, presumably, an XE with ECI port).  That shim upgrade wouldn't be required for any machine other than the 600XL.  Am I headed in the right direction?

 

Yes

 

Sincerely

 

Mathy

 

[Mathy]

Hello manterola, guys

 

21 hours ago, manterola said:

I would love to see and have that: an tf_hh 576K expansion but external (PBI), with pass-thru (with the option to disable XRAM, and just provide the Std.64K)

 

On a 800XL that would switch the internal 64kB off.  Not sure if it could/would do the same in an XE.  Either way, you "loose" 64kB, either internal or external.  That would bug the hell out of me.  With a small redesigned 1064, you could basically turn the 600XL into an 800XL.  Eliminating the need for two different external memory expansions, one for the 600XL and another for the 800XL.

 

Sincerely

 

Mathy

 

[Mathy]

Hello Bob, guys

 

20 hours ago, bob1200xl said:

I can see this as a cable on the PBI (like the MIO) and the memory module as a tidy 'bump' on the cable.

 

Way back when I used my BlackBox a lot, I used the MIO extender board to create a flexible connection between my XE's and the BlackBox.  That way, if I somehow moved the XE, the connection would hold.  Plus it gave me more room between the BB and the XE.  An redesigned 1064 could be just a short board, no(t much) wider than the PBI connector, that plugs directly into the 600XL, maybe with two rubber feet, with a passthrough on the back.

 

Sincerely

 

Mathy

 

[+x=usr(1536)]

29 minutes ago, Mathy said:

On a 800XL that would switch the internal 64kB off.  Not sure if it could/would do the same in an XE.  Either way, you "loose" 64kB, either internal or external.  That would bug the hell out of me.

I understand what you mean by this, but with a 1064 you still lose 16K ?

 

Being serious, though, any memory attached to the PBI will effectively disable the on-board memory, at least from my understanding of how the PBI works.  If this is correct, then there's no way around it - you have to replace the base memory regardless.  You're not really losing anything by going the PBI route since it wouldn't have been available in that case anyway.

29 minutes ago, Mathy said:

With a small redesigned 1064, you could basically turn the 600XL into an 800XL.  Eliminating the need for two different external memory expansions, one for the 600XL and another for the 800XL.

I'm not sure that I understand how this doesn't create two memory expansions: one to bring the 600XL up to 64K, and another to work with both the 600XL and 800XL ?‍♂️

[Mathy]

Hello x=usr(1536)

 

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

I understand what you mean by this, but with a 1064 you still lose 16K ?

 

I know.  There's no way around that, unless you are willing to do an internal upgrade of the 600XL to 64kB.  But that's not what this discussion is about.  The redesigned 1064 would be a solution for those who do not want to do an internal upgrade.

 

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

Being serious, though, any memory attached to the PBI will effectively disable the on-board memory, at least from my understanding of how the PBI works.

 

The methode mostly used at the moment is that all expanded memory in the computer is disabled.  Not main memory.

 

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

I'm not sure that I understand how this doesn't create two memory expansions: one to bring the 600XL up to 64K, and another to work with both the 600XL and 800XL ?‍♂️

 

Yes, but the one that brings the 600XL to 64kB would be very small and can be used with every external upgrade that can be used on the 800XL.  Meaning you only need one person to redesign the 1064.

 

Let's say a couple of people all design their own external memory extensions, for instance:

 

- Person A

- Person B

- Person C

 

If these people would want their external memory upgrades to work with both the 600XL and the 800XL, they would have to make two versions of that external memory upgrade.

 

With the redesigned 1064, they would only need to develop one version that you could plug into the 600XL (with the redesigned 1064) as well as the 800XL.  (But not at the same time, of course.  :-) )

 

Sincerely

 

Mathy

 

Edited June 15, 2021 by Mathy

[+x=usr(1536)]

11 hours ago, kheller2 said:

While the 1064 does have 64k, the upper 48 are mapped and the internal 16 still used.  That’s the funkyness of that LS32 chip on the 600.  The 1064 also has one. I’m not sure why they just didn’t kill the onboard  unless that isn’t possible with that chip. 

I'm not 100% certain that this is correct - my understanding is that RAM on the PBI bus will disable internal RAM, which means that all 64K on-board the 1064 will be used.

 

Please tell me if the following makes sense or not; I'll freely admit that I'm not always the sharpest marble when it comes to the deeper workings of hardware.

 

The 600XL - by default - can address 64K of RAM, but only use 16K of it.  This is why it is necessary to modify (with jumper wires) the 74LS158 and 74LS51 that handle memory multiplexing on a machine receiving an internal 64K upgrade: yanking the 16K RAM ICs and replacing them with 64K RAM ICs will work, but you'll still only be able to use 16K of RAM.

 

WRT the 1064's internals, I'm using this picture for reference:

 

 

The two columns of ICs on the left appear to be for address multiplexing, while the two columns on the right are the RAM.

 

If the 600XL was internally-capable of using all 64K without modification, the entire addressing section on the 1064 would be unnecessary, as would two of the 4864s in the RAM section.  However, that would also make the 1064 a redundant peripheral, since the upgrade it provides would be able to be done internally from the start just by replacing the 16K RAM ICs with 64K RAM ICs.

 

The 1064 appears to be (effectively) replacing the 600XL's on-board RAM and multiplexing logic with its own.  In a way, it's as though it was grafting the equivalent of that section of an 800XL onto the 600XL, which is kinda nifty.

 

If I'm wrong on any of this, I'll happily accept corrections.  Like I said, I'm not the world's smartest hardware inner-workings guy.

[Mathy]

Hello x=usr(1536)

 

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

WRT the 1064's internals, I'm using this picture for reference:

 

You can also use the original schematics which you can find on my Docs page.  That is if you can read them.

 

Sincerely

 

Mathy

 

[+kheller2]

 

[+x=usr(1536)]

57 minutes ago, Mathy said:

I know.  There's no way around that, unless you are willing to do an internal upgrade of the 600XL to 64kB.  But that's not what this discussion is about.  The redesigned 1064 would be a solution for those who do not want to do an internal upgrade.

We're on the same page about that

58 minutes ago, Mathy said:

Yes, but the one that brings the 600XL to 64kB would be very small and can be used with every external upgrade that can be used on the 800XL.  Meaning you only need one person to redesign the 1064.

 

Let's say a couple of people all design their own external memory extensions, for instance:

 

- Person A

- Person B

- Person C

 

If these people would want their external memory upgrades to work with both the 600XL and the 800XL, they would have to make two versions of that external memory upgrade.

 

With the redesigned 1064, they would only need to develop one version that you could plug into the 600XL (with the redesigned 1064) as well as the 800XL.  (But not at the same time, of course. ? )

Understood.  I'm just not seeing the advantage to having a separate upgrade specific to the 600XL when a single box could do it all.

 

We're in agreement on the idea, just not the approach ?

[+bob1200xl]

So, looking at the schematic:

 

you don't need

 

74ALS245

 

2x 74ALS137

 

8x 4164

 

the rest of the ICs

 

 

What do you need:

 

64K SRAM  (probably easier to find larger chips...)   32 pins

 

CPLD     20 pins

 

Bob

 

[+Larry]

Would it be possible to make a "universal" 600XL/800XL upgrade that one could jumper to select?  That would seem to be what Ctirad attempted with the RAM 800XL. (Which was quite popular, BTW.)

[+tf_hh]

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

I'm not 100% certain that this is correct - my understanding is that RAM on the PBI bus will disable internal RAM, which means that all 64K on-board the 1064 will be used.

 

Please tell me if the following makes sense or not; I'll freely admit that I'm not always the sharpest marble when it comes to the deeper workings of hardware.

 

The 600XL - by default - can address 64K of RAM, but only use 16K of it.  This is why it is necessary to modify (with jumper wires) the 74LS158 and 74LS51 that handle memory multiplexing on a machine receiving an internal 64K upgrade: yanking the 16K RAM ICs and replacing them with 64K RAM ICs will work, but you'll still only be able to use 16K of RAM.

 

Why ever, but Atari did design it this way. When the 1064 is plugged to the 600XL, only the "last" 48 KByte ($4000-$FFFF) are mapped external. The first 16 KByte are always used internal. Easy test: Remove the both internal DRAM Chips - your 600XL won´t start ?

 

The internal wires are only needed to expand the multiplex address space from 16K to 64K. The inputs for the highest addresslines A14 and A15 are fixed to ground at the 600XL mainboard, so only A0...A13 is used, which means 16K address space. So the wires just add the missing both address lines and the 3rd one will enable generation of "CAS" for the whole 64 KB address space - by default it´s internal limited to 16K, too.

 

[+Larry]

Are the Atari user docs for the 1064 posted somewhere?  (Not looking for schematic.)

[Peri Noid]

http://jsobola.atari8.info/dereatari/atarisch/1064.zip

[+x=usr(1536)]

5 hours ago, tf_hh said:

Why ever, but Atari did design it this way. When the 1064 is plugged to the 600XL, only the "last" 48 KByte ($4000-$FFFF) are mapped external. The first 16 KByte are always used internal. Easy test: Remove the both internal DRAM Chips - your 600XL won´t start ?

Hm, OK.  Guess I was wrong - I always thought that the internal 16K was disabled if there was RAM on the PBI bus.  I agree with you, though - that's just not great design.  It doesn't make much in the way of sense.

5 hours ago, tf_hh said:

The internal wires are only needed to expand the multiplex address space from 16K to 64K. The inputs for the highest addresslines A14 and A15 are fixed to ground at the 600XL mainboard, so only A0...A13 is used, which means 16K address space. So the wires just add the missing both address lines and the 3rd one will enable generation of "CAS" for the whole 64 KB address space - by default it´s internal limited to 16K, too.

Understood ?  So, out of curiosity, how is the upper 48K of RAM on the 1064 mapped in?  I'm assuming that it's handled by the logic on the 1064, but don't quite get how that would work with what's already in the 600XL.

 

As an aside: the only reason I can think of to do deliberately limit addressing would be to protect 800XL sales; being able to just swap out two RAM ICs in a 600XL for 64K equivalents would make it almost too easy ?

[+kheller2]

I must still not understand the 600XL and PBI design correctly.  Because why couldn’t you just lift  pin 1 of U3 in the 1064 and tie it high so the entire address range is used?  Hmm that’s bad if the address lines are all 0. 

[+tf_hh]

1 hour ago, kheller2 said:

I must still not understand the 600XL and PBI design correctly.  Because why couldn’t you just lift  pin 1 of U3 in the 1064 and tie it high so the entire address range is used?  Hmm that’s bad if the address lines are all 0. 

 

I would suggest not to focus on PBI device or - design. The 1064 uses RAS and CAS lines, IMHO these signals are only attached to the PBI to support the 1064. Later XE machines haven´t these signals at the ECI. And, the first XL O.S. version (rev. 1) found in early 600XL machines hasn´t any PBI support as we know it from today. So if you have an O.S. ROM with the marking CO62024 instead the well-known CO61598, no PBI device like the KMK-IDE or MSC or the BlackBox won´t run, because this O.S. hasn´t the PBI protocol built in.

 

You could make run / use the 1064 completely. Remove the 74LS32 chip and make a bridge between pin 8 and 10. The disables the "CAS16K" generation, so CAS (at the PBI) is enabled for all adresses to the PBI, and not only for adresses from $4000 up. Of course you must remove existing DRAM chips from the 600XL mainboard ?

 

 

[+tf_hh]

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

So, out of curiosity, how is the upper 48K of RAM on the 1064 mapped in?  I'm assuming that it's handled by the logic on the 1064, but don't quite get how that would work with what's already in the 600XL.

 

Using standard CAS and RAS signals attached to the PBI. RAS is always active (for internal and external DRAM), because it´s needed for DRAM refresh. CAS (the CAS signal at the PBI) is latched using the 74LS32 and the 74LS375. As long A14 and A15 are low, the CAS transistions are only mapped to the internal DRAM. External CAS signal remains high. The simple reason why Atari design it this way: There was no possibility to "turn off" the internal DRAM without  disabling the whole DRAM circuitry (like modern expansions do this with setting EXTSEL to low). So Atari can´t make another way to integrate the external expansion w/o modding the 600XL.

 

[+tf_hh]

6 hours ago, Larry said:

Are the Atari user docs for the 1064 posted somewhere?  (Not looking for schematic.)

 

User docs? Didn´t know about any. But... when there´s something, what may be printed on it more than "Plug the 1064 into your computer´s parallel connector and you´re done"?