SRAM for C64 (and maybe 600XL)

[plazma]

I made a compact PCB which replaces DRAM with SRAM and fixes the VSP bug. It fits 466 & 469 motherboards. I'll place some for sale after I receive the correct SRAM chips. I ordered wide SOIJ case by accident. It did fit the PCB anyway and I could test the protype. This should also work with 600XL. My 600XL is dead at the moment so can't test. 

[norm8332]

Nice, but you really don't want to fix the VSP bug since some games and demos use it.  Super Mario Bros comes to mind...

[+OLD CS1]

On 6/24/2019 at 5:36 PM, plazma said:

I made a compact PCB which replaces DRAM with SRAM and fixes the VSP bug. It fits 466 & 469 motherboards. I'll place some for sale after I receive the correct SRAM chips. I ordered wide SOIJ case by accident. It did fit the PCB anyway and I could test the protype. This should also work with 600XL. My 600XL is dead at the moment so can't test.

 

I thought VSP has become less of a bug and more of a feature.

 

@norm8332 beat me to it

[plazma]

VSP trick is used for horizontal scrolling. The VSP bug crashes machines when using sw with the VSP trick.

One of the games using the VSP trick is Mayhem in Monsterland. 

 

Machines with the VSP bug may hang or have glitches when using SW with the VSP trick. With this SRAM board that bug is gone and VSP trick  SW works. 

http://www.linusakesson.net/scene/safevsp/

Edited June 26, 2019 by plazma

[plazma]

You can use the VSP Lab program to check if your machine got the VSP bug. Let it run for few hours. The bug may appear after the chips warm up. 

https://csdb.dk/release/?id=120810

[norm8332]

1 hour ago, plazma said:

VSP trick is used for horizontal scrolling. The VSP bug crashes machines when using sw with the VSP trick.

One of the games using the VSP trick is Mayhem in Monsterland. 

 

Machines with the VSP bug may hang or have glitches when using SW with the VSP trick. With this SRAM board that bug is gone and VSP trick  SW works. 

http://www.linusakesson.net/scene/safevsp/

 

If that's how it works, great. Thanks for clearing it up.

[+DrVenkman]

You reference the use in a 600XL - Lotharek in Poland has recently introduced an SRAM module that he is (or very soon will be) selling in versions for a number of retro 8-bit systems, including the A8 (XL and XE models), some Sinclair models and a few others I believe. 

[plazma]

Received the correct SRAM chips. Looks little better.

[shoestring]

This should also work in some XEs and the later Apple IIes ( Platinum board ) with the two 4464 DRAM configuration.

 

[+OLD CS1]

That looks really nice.  Are you selling these?  I might want to grab a couple for the inevitable need.

[R.Cade]

14 hours ago, shoestring said:

This should also work in some XEs and the later Apple IIes ( Platinum board ) with the two 4464 DRAM configuration.

 

Both my 130xe's have 16 * 4164's in them... Did they make a revision with 4 * 4464's?

 

[shoestring]

 

Yes. This is my 65XE below which I practically rebuilt ( if you're wondering about the sockets ).

 

Atari did use the 130XE PCB in later 65XE models, presumably to save costs and just use the same PCB layout for both.  As you can see the 2 other rams and EMMU are missing.

 

 

And a 130XE with 4 x 4464 dram.

 

 

 

Edited August 19, 2019 by shoestring

[plazma]

5 hours ago, OLD CS1 said:

That looks really nice.  Are you selling these?  I might want to grab a couple for the inevitable need.

Yes. I sell them. I have tested it with C64 250466 & 250469 motherboards only.

Kit 12€. Assembled 17€. Shipping EU 2,30€. Non-EU 3,50€.