Help Identify Strange 800 OS and RAM cards

[Paul Westphal]

Hi guys,

I picked this 800 off a guy who worked at Atari. I hit it with a SALT cart and got:

OS :

High checksum 5A02

Low checksum EC9F

Math checksum calculated : D8A7

Math checksum found : 42FA

PLUS : it has a weird ram card in second slot.

[Paul Westphal]

It appears the OS has a EEPROM.

[Paul Westphal]

I tried Mario bro's. XE, thinking it might be 64k, no dice. Ballblazer works.

[sup8pdct]

Ram card looks like it may have ram expansion like Axlon . Try booting superdos or SDX on it.

 

James

[DavidMil]

If those are 256K RAM chips, that is the Axlon RAMDISK MOD. I believe that David Byrd did that one.

Along with modifications to the RAM card there were some changes to the ROM card too. On the lower

right corner of the RAM card are there a couple of traces cut by C518? If so, this is the Axlon 256K

RAMDISK Modification. This Mod was designed to give you a very fast virtual double density disk drive,

so that DUP.sys and MEM.sav could be made resident and switching between programs and DOS would be almost

instantaneous. It was designed to run with GENEEMDE (by H. V, Stacey) under DOS II (2.0S). If anybody

has that program (not DOS 2.0S) I would like a copy of it too.

 

Thanks,

David Milsop

[Paul Westphal]

Yeah those are 256k ram chips. If this is the ramdisk mod, then most likely other programs may not see the extra ram, but I will try some demos.

[Paul Westphal]

I tried super dos. After initializing, detected the high speed on my SIO to SD, then loaded fast. It's an interesting DOS.

[DavidMil]

The EPROM in the 2K math socket (402) is unknown to me. I have a Fast Math chip in my 800 but

the checksum is 5B68. This one may stump a lot of people. If you find out what it is, would you mind

posting the info?

 

Thanks,

DavidMil

 

By the way, if I had looked at your picture I would have seen the two traces cut by C518.

David

[sup8pdct]

I tried super dos. After initializing, detected the high speed on my SIO to SD, then loaded fast. It's an interesting DOS.

Superdos should show a density in 5+.that is ramdisk. pressing 5 should give a directory listing of the ramdisk.

If using superdos, you can save the rom out to a file for others to look at.

 

Superdos is designed to be a direct replacement for dos 2.

 

James

 

James

[sup8pdct]

The rom board is a puzzle. it has an extra decoder chip and 2 wires going through the hole 2 the back side. a pic of the back side may help.

It also has REV B ntsc os.

 

James

[1050]

Connection to pin 7 of the piggybacked 74LS138 on the OS board may mean it's like

a couple of custom AXLON type upgrades I have with the difference that instead

of 0xCFFF, it banks with access to 0xD700. Change your software to bank there

and it will work if this is the case. Mine were not built like this one, pin 7

is normally not used so no need to piggyback another chip there. I suspect it

may have other talents unknown at this time. Such as software on/off where

mine had a hard wired switch.