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Member Since 11 Apr 2010
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#4027807 Were there any alternative OS or CPU cards for the 800?

Posted by BillC on Mon May 14, 2018 10:24 PM

There were 2 different OEM CPU cards for the 400/800, the original used the standard 6502B, while the later version used Atari's custom 6502C(AKA Sally).


There is also the 400/800 Super Color CPU card by tf_hh, the later version includes Bryan's UAV video upgrade.

http://atariage.com/... 800 cpu card


Then there is the alternate OS card for the 800 called the Ramrod MMOS. I believe it's main purpose was for use with the Newell products, OSN/Omnimon/Omniview.

#4027417 SIO2PC usb printed Case (WIP)

Posted by BillC on Mon May 14, 2018 9:07 AM

OK - only reason I ask, is I made a super shitty - simple, box for my device.  Literally, a black box.  I miss the LEDs though, so I want to somehow bring them out.  I may order new LEDs, and use the longer leads to bring the actual LED to the box, rather than trying the light pipe approach.

This is what ICD did with the LEDs on the MIO, they also countersank the inside of the holes so the LEDs were just below the surface.

#4025931 ICD P: R: connection..

Posted by BillC on Fri May 11, 2018 8:00 PM

Atari couldn't use thr PC standard 9-pin serial port since it didn't exist at the time, the 850 was released several years before IBM introduced it on the AT computer.

#4020182 800 power supply caps replace

Posted by BillC on Thu May 3, 2018 12:46 AM


This is a ceramic capacitor. At normal circumstances you don´t need to change ceramic caps. Most times they´re working fine or simply cause a short-circuit :-D

That's C203 which, according to the parts list in the back of the Field Service Manual, is a 0.22uF(100V) poly film capacitor.

#4017073 What is this thing?

Posted by BillC on Sat Apr 28, 2018 1:57 PM

B&C/myatari.com still sells 810 Happy upgrades for $99, and also upgrade ROMs for older Happy 810 upgrades for $24.95(2 versions depending on Happy PCB serial#).

ACA008    HAPPY 810 UPGRADE              99
Turns a stock 810 into a 810 Happy drive
ACA009    HAPPY 810 ROM UPGRD >5000      24.95
ACA010    HAPPY 810 ROM UPGRD <5000      24.95
Upgrade Rom for original 810 Happy Drives

#4008184 Have a spare Newell OSN and Fastchip?

Posted by BillC on Sun Apr 15, 2018 9:47 AM

Well, after 3 years of watching and searching I found a real Newell Fastchip and have it installed in my RAMROD MMOS board along with OSN and it seems to work just fine! I have Omnimon also, but the version I found on AtariAge seems to differ from the manual on archive.org. It's version Omnimon A1 and while it seems to work, the commands are different (mostly).


My 800 now has graphics modes 12-15 so I'm assuming OSN is working correctly, I believe those were only available on the XL models. I ran a few calculations using floating point, so my basic test of the Fastchip seems to show it's working as well.


I've attached a photo because I know people like that stuff.


Not sure what I'll do now that I found my unicorn  ;)

Better cover up the windows on the EPROMs!

#4001953 Early 800 only showing B/W

Posted by BillC on Thu Apr 5, 2018 11:23 PM

I was looking back at the post I linked to with the same issue someone else was having and the schematic.  For the other person I suggested looking at the 10pF cap inline with the color signal(I don't know if they tried checking/swapping it or not).  It is the 10pF between R196 and pin 12 of A104.  This cap is not labeled on the schematic other than the value.

The Sobola schematics show this as C161, and that is the only 10pF capacitor I found listed for the main PCB in the Parts List in the back of the Field Service Manual

#4000479 Would this be an alternate (with WiFi) to the Lantronix UDS-10

Posted by BillC on Wed Apr 4, 2018 2:15 AM



Thanks for the heads up on these.  Just ordered one.  Have a P:R Connection as well to hook it up with.  :-)

I have read that the P:R:C is supposed to be able to manage 19,200, I know that the MIO is capable of that.

#3999434 One Last EPROM

Posted by BillC on Mon Apr 2, 2018 6:17 PM


Check which of the 2 jumper configurations you have above U10 on your 1050 mainboard, If you have JP2 & JP4 jumpered, you can simply remove the ICD ROM at U10, and swap it with a 2732 EPROM programmed with this replacement code.


I suspect most of the original USDoubler ROM's were really EPROMs inside, or at least made pin-compatible. There is mention in the manual of being able to send in for a different 'U10' chip that works with the JP1/JP3 configuration (Mask ROM) for those that didn't want to solder.

The USDoubler ROM chips for the 'Mask ROM' jumper position are 2532 EPROMs, they are pin compatible with the original 2332 ROM chips.


Atari seems to have made the 1050 drives flexible enough to take either, probably in case they needed to introduce a newer firmware before updated mask ROMs were available.


They did similar on some verions of the 600XL PCB as well, having 2 jumpers which allow the BASIC chip to be either a 24-pin ROM or a 28-pin 2764 compatible EPROM.

#3981748 Simple (single) RS-232 interface ?

Posted by BillC on Fri Mar 9, 2018 5:42 PM

BITD there were loads of centronics/parallel/printer interfaces for the A8 as alternative to the 850......but were there any RS-232 alternatives ?


With a single RS-232 port ?


I think it would be a breeze to build one, as the very first SIO2PC I built into my 130XE in the late 90's was simply a "piggy back" solderered MAX232 chip on the SIO port, just because it needed the +5 and 0V levels from the SIO port converted to standard RS-232.


But was there anything "production" like...maybe something compatible with the 850 software wise ? 


I'd like to hook up a RS-232 printing device to the A8....a simple schematic would be fine too....but there needs to be some simple software support from BASIC....

I believe the serial SIO2PC was an adaptation of the R-Verter interface, adding the COMMAND signal connection to one of the RS232 handshake lines.


Commercially the R-Verter was used as an external device by Supra for Atari 8-bit compatibility, I have one I got with a Supra 2400 modem in the late 80's, and also internally by Atari in the SX212.


A disadvantage of the R-Verter interface is that there is no handshaking available to implement hardware flow control.


The CSS Black Box is the only device I know of which came with RS232 hardware flow control, but there is a replacement serial port driver for the MIO which adds this feature.

#3974270 XEGS Questions

Posted by BillC on Wed Feb 28, 2018 4:10 AM

Instead of getting an XEGS keyboard you could instead get one of Michaels Transkey-II adapters which allow the use of a PS2 keyboard.

There are versions which plug into the XEGS keyboard port, no internal modification required.



#3969211 Cartridge Repair?

Posted by BillC on Thu Feb 22, 2018 3:07 AM


Well.. Got a new (to me) brown shell 1983 "E.T. Phone Home" cart today, cleaned up the contacts and played it for a few minutes 'out of the shell'. Then a darned static zap from my fingers fried it due to the dry/cold weather here lately... only black screen now on powerup.
16KB game, 2x8KB 24 pin chips. 27C64 EPROM is 28 pins, so that won't fit. Is this board for all practical purposes a throwaway or is there a potential way to wire in an EPROM?
Does this PCB from B&C fit in an Atari brown-shell cart case?

PRA062   PCB CART board 16K for EPROMs W/SOCK  8.00 2-2764s

That PCB does fit the brown shell, they can also be modified to act as an 8k PCB with a single 2764 if desired.


The other 3 at the very bottom of the list are the ones that don't fit the brown Atari cartridge shells.


Atarimania does have a downloadable ROM file for this game, it would necessary to be split it into 8k blocks for burning to 2764s.


#3969161 800 power supply caps replace

Posted by BillC on Thu Feb 22, 2018 12:50 AM

PDFs of the Atari 400-800 Computer Field Service Manual and Sams Computerfacts Technical Service Data - Atari 800 are both available from Atarimania.



#3965748 Atari 800 S-Video Problem

Posted by BillC on Sun Feb 18, 2018 1:36 AM

Could the color differences be due to CTIA vs. GTIA? Do you know which chip your 800 has?


I don't remember any color difference between the CTIA & GTIA, but is has been over 30 years since I have had a CTIA. The GTIA does have more video modes.


The color on the Atari computers can be adjusted via a potentiometer.


On the 800 this potentiometer is on the CPU card, and can be adjusted through a hole on the back of the RF shield when the cover for the RAM/OS card bay is removed.

#3962270 Anyone sell an Atari 400 capacitor kit?

Posted by BillC on Wed Feb 14, 2018 4:52 AM

For posterity and to help with the project, as it may be needed someday... maybe someone would be inclined to post the 400's build out sheet or maybe he could simply look through a bunch of photo facts etc.

The parts list for the 400 is already in the back of the 400-800 Home Computer Field Service Manual, available at Atarimania.