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Atari 800 256Kb upgrade


ebiguy

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On 1/11/2019 at 8:48 PM, archeocomp said:

Thank you. As it is verified now, I would like to share PCB with community. They (3 pieces including shipping worldwide for USD7.70) can be ordered or downloaded at https://oshpark.com/shared_projects/Fr8n4LQ7

Is this a remake of a later Buchholz QMEG RAM, one sold by Wizztronics, with the option for A400/A800 ANTIC removed? It doesn't have independent CPU/ANTIC bank switching? Is it any different from RAMbo 256kB?

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Yes, it is remake of a later Buchholz QMEG RAM. I can not answer later questions, as I am not that involved. I just found a (dated) text file, describing what is needed and made PCB. This should say it all: QuarterMEG Atari 800XL, XE compatible, for Ataris with C021697 (or C021698), schematics Claus Buchholz. Actually ClausB should be able to give more insight :-)

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4 hours ago, walter_J64bit said:

I have an 800 that has 288k it was installed by Bruce from B&C ComputerVisions back in the day I've installed a fastchip in it too. It's not 130XE Compatible but I do wish it was, the most I can do is use RAM disk's with it.

It's likely AXLON compatible, there was a company called Magna Systems which manufactured this type of 800 RAM board up to 1MB.

 

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10 hours ago, walter_J64bit said:

AXLON compatible you say, I do recall seeing an 800 RAM board up to 1MB and a 64k up grade for the 400 too. 

Axlon made 32/128/256KB boards for 800, their bank selection method was later used by Magna Systems to make compatible boards up to 1MB.

 

Mosaic made a 64KB board compatible with the 400(once some jumper wires were added to the 400 PCB), up to 3 could be used in the 800.

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On 2/19/2020 at 7:36 PM, walter_J64bit said:

I have an 800 that has 288k it was installed by Bruce from B&C ComputerVisions back in the day I've installed a fastchip in it too. It's not 130XE Compatible but I do wish it was, the most I can do is use RAM disk's with it.

There are actually some productivity applications that recognize extra 800 Axlon compatible memory, which I'm sure it probably is, so it could do more than just ramdisks. The problem was that advertisements of the programs never mentioned use of 800 extended memory boards, you found out in the manual or within the program itself. Even when some were revised for XE extended memory, and advertised for it, they still did not mention 800 Axlon memory even though they were still also compatible with it. I know Synapse' Syn-series like Syncalc and Synfile. And some word processors and other apps too, like some of the programs in XLEnt Software's Printware series.  

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3 hours ago, Gunstar said:

There are actually some productivity applications that recognize extra 800 Axlon compatible memory, which I'm sure it probably is, so it could do more than just ramdisks. The problem was that advertisements of the programs never mentioned use of 800 extended memory boards, you found out in the manual or within the program itself. Even when some were revised for XE extended memory, and advertised for it, they still did not mention 800 Axlon memory even though they were still also compatible with it. I know Synapse' Syn-series like Syncalc and Synfile. And some word processors and other apps too, like some of the programs in XLEnt Software's Printware series.  

Synfile+(probably Syncalc as well) also supports the Mosaic 64K card, which even gives an extra 4K RAM for BASIC programs with a "POKE 106,208"(increases RAMTOP to 52K).

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8 hours ago, Gunstar said:

There are actually some productivity applications that recognize extra 800 Axlon compatible memory, which I'm sure it probably is, so it could do more than just ramdisks. The problem was that advertisements of the programs never mentioned use of 800 extended memory boards, you found out in the manual or within the program itself. Even when some were revised for XE extended memory, and advertised for it, they still did not mention 800 Axlon memory even though they were still also compatible with it. I know Synapse' Syn-series like Syncalc and Synfile. And some word processors and other apps too, like some of the programs in XLEnt Software's Printware series.  

I'm sure there are apps that work with the extended memory, when I've got the 800 I was just a kid at that time so I'd not know much about ram upgrades. It's all good, when I get a brake from my homework I'm going to look at apps that work with the extended memory.

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On 2/21/2020 at 12:12 AM, BillC said:

Synfile+(probably Syncalc as well) also supports the Mosaic 64K card, which even gives an extra 4K RAM for BASIC programs with a "POKE 106,208"(increases RAMTOP to 52K).

Hmm.. this would indeed move the display to the upper 4KB, but the BASIC ROM would still be stuck in the middle of the program area, and a large program would eventually try to write into the ROM. A graphics mode larger than 4K would also map into the ROM...

 

linear 52K modes are best used without a cartridge present, and the 4KB above the ROM is best used in BASIC directly for data storage, like character sets, p/m data, or indirectly via a RAMdisk...

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7 hours ago, Nezgar said:

Hmm.. this would indeed move the display to the upper 4KB, but the BASIC ROM would still be stuck in the middle of the program area, and a large program would eventually try to write into the ROM. A graphics mode larger than 4K would also map into the ROM...

 

linear 52K modes are best used without a cartridge present, and the 4KB above the ROM is best used in BASIC directly for data storage, like character sets, p/m data, or indirectly via a RAMdisk...

The Mosaic 64K review linked in post #83 suggests putting DATA or ML subroutines in the 4K bank, and there are 4 separate banks available if needed. BASIC programs shouldn't be able to access ROM space if RAMTOP is set correctly.

 

 

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