Yet Another Ram Upgrade question

[ClausB]

The wire numbers make it hard to decipher. Could you add these signal names to the schematic? They correspond to the 800XL schematic.

 1 Switch
 2 /RAM
 3 PB2
 4 A14
 5 PB3
 6 A15
 7 RCS
 8 A6
 9 A7
10 RA6
11 RA8
12 RA7
13 LR/W
14 /D6xx
15 D1
16 D0
17 /Phi2
18 /RST
19 /HALT
20 Clk
21 GND
22 +5V
23 25
24 PB4
25 23
26 PB6
27 PB5

 

[Cheshire Noir]

7 hours ago, ClausB said:

Thanks. Two possible mistakes:

 

Output U6 pin 12 connected to output U4 pin 3.

Output U6 pin 9 to output U4 pin 6.

Hooboy. Glad you're checking. Basically I got chip 3 and 4 mixed up in a couple of places when plotting out chip 6. Working on a new version now.

[ClausB]

While Chesh is getting cross-eyed starting at wires and chips, I've teased out another detail from his schematic. There is only a single 2-bit configuration register at address $D6xx. Purpose still unknown.

[Cheshire Noir]

OK I have put the board back in my system.

Mind you it now looks like this:

So considerably neater.

I've also uploaded all my KiCAD stuff to my github: https://github.com/cheshirenoir/AtariMemEx

It's the "final" version, as to do any more work, I'd need to open up the Atari again, and I just want to play some games for a bit. Pharaohs Curse, here I come!

 

Thanks for everyone's help! 

[ClausB]

It appears the register outputs go to two gates and the "jumper" cuts, so they no longer have any effect on the circuit. The rest of it seems to be equivalent to the circuit I posted, but I'll double check.

[ClausB]

Correction to the label for wire 2:   /A14

 

A15 goes through the switch.

 

Possible mistake: U6 pin 5 should go to ground.

 

With those, the banking circuit is equivalent to what I drew above except that it includes HALT, so it won't bank for ANTIC (not at all, unlike the 130XE). Otherwise it should behave as a RAMbo, as we saw in the test screen.

 

[ClausB]

If you look at the circuit before the 2 "jumper" cuts were made and the 2 "bodge" wires 26 & 27 were added, it appears that the configuration register was used instead of PB5 and PB6 for bank selection. So maybe the original boffin designed it for pure 130XE compatibilty with an optional extension to 256K.

Edited February 28, 2021 by ClausB

[Cheshire Noir]

On 2/28/2021 at 2:45 AM, ClausB said:

Correction to the label for wire 2:   /A14

 

A15 goes through the switch.

 

Possible mistake: U6 pin 5 should go to ground.

 

With those, the banking circuit is equivalent to what I drew above except that it includes HALT, so it won't bank for ANTIC (not at all, unlike the 130XE). Otherwise it should behave as a RAMbo, as we saw in the test screen.

 

Thanks for those.

I'll fix those up and reload it up to the repository in the next few days. Been working on other systems today and yesterday. (Fixed my Creativision and made a brand new joystick for my Apple II)

 

Chesh

[+Peter Rabitt]

Quick Question... I have a something like the Memory here and it looks like one of the ClausB ckt's The problem I am having is the memory chips are getting very warm. They are 41256 -150. Also the *** thing stopped working and does not boot or any video..  I had to solder some of the broken wires back but they did not help. any ideas???

 

Peter

[ClausB]

Check your power supply for +5 VDC.

[+Peter Rabitt]

Power supply is good. Checked at the memory chips and it is 4.96 or so. I do have one thing that also happen, the "power light" does not light in this mode...

Still working on getting the PCB and all the parts together so maybe the problem is a broken solder joint again.

 

Thanks

 

Peter

[_The Doctor__]

if you turn on the extra banks and your led goes out, you have a shorted something, or misswire... possible solder bridge. Your supply is tested under load and looks clean under a scope I presume. So look for bits of solder, wire, flakes, or blobs... make sure the wires are where they belong... after that it's time to check your ram chips... one or a few may have died and shorted

[+Peter Rabitt]

Yea I hear you on the "extra"wire/blobs... What is happening is it works sometimes and not the next. the light was off about 2-3days ago, so I ordered anew one. Then the next time I closed up the 800 the light was on.. Don't know it is powered thru the keyboard connector so i kinda think it could be their. Still looking.. The 800xl was a work horse when it was working on the BBS but now 35 years later it has gone to the dogs..HAHAHA I think most of my problems are that I do not have all the parts and they may work together... The atr-8000 was the system,using CP/M to run the HD/FD etc. could be the problem is I have not hooked up the ATR to the 800xland booted it up from their..I will get their soon, I hope..

 

Peter

[_The Doctor__]

No, it's not any missing add on or peripheral... the machine should work, stand alone.

You should either get you basic ready prompt, or the self test if it's and XL/XE machine

Memo pad if a plain ole 800 etc.

Edited June 7, 2021 by _The Doctor__

[+Peter Rabitt]

Quick answer, No I do not get the basic (800xl) or memo pad. and I tried the opt to get the self test but nothing...I guess 35 years get things to die.

Sometimes it has rolling screen in color. If I push the "reset" button it goes to "black" and no movements on the screen then i power off wait a sec or so power back on and it shows video(not a blank screen) but no movement. I know it is real bad.. I know there other part in the garage in boxes but I am kinda disabled so lifting the boxes is hard.

 

Peter

 

 

[_The Doctor__]

I worry about your power supply, I would not connect other peripherals until your computer itself is sorted out

[+Peter Rabitt]

I just bought the p/s for the 800xl because I could not find the Atari one..I have measured the voltages with a DVM and they are, at the memory chips , 4.96 or so.. I check other places but as I started to work on the 800 more and more wire for the memory upgrade broke and I stopped until get all the parts to redo the memory controller upgrade . Maybe by monday or so...

 

[+Peter Rabitt]

Sorry I let this thread hanging..I hate when I read a thread and it just stops with a question or ???.

Any way I have updated the 800XL with the bought memory update board and cleaned up the inside of the computer..All is working except the "ON" led is still out but the rest works GREAT. I can use fujinet ,the sdrive, etc. It talks to the 1050 drives etc...IT Works...

O yes I am now on the ST side of my Atari stuff trying to figure out what I did???

I have 2 520stm and one had a memory upgrade,(2,5meg), but thats all so far as the psu's have not been checked out yet...

See my rambling in the ST side of this form..

 

Peter

[Kyle22]

On 2/20/2021 at 9:20 PM, Nezgar said:

I fully agree regarding the benefits of the main memory mirroring...

 

Just refreshing my memory here... (there's a pun...) But reviewing the A8FAQ the "original" Peterson type upgrade description notes that main memory was protected from banking, and something about bit 5 being "inverted" compared to RAMBO type upgrades (what does that mean?), and later mods supplied after "Rambo" type upgrades gained popularity to allow banked access to main memory and ANTIC access to banked memory switched to CPU calling the "256KXLE"

 

Methinks there may be a connection here....

IIRC, if you invert Bit 5on the Newell upgrade, it becomes RAMBO compatible.