I have a 1200XL and did Bob Wooley's PBI mod to it.
I want to run my CSS BlackBox with Floppyboard on it. The BB is okay and running on my
1500XL Laptop; if you remember, it has a 600XL inside.
On the 1200XL, however, it refuses to work. No booting from HD, no BB menu coming up
when menu button is pressed. Other tahn that, 1200XL works as before.
800XL OS and MMU it already had working a long time.
In the text linked above, i think i found one error when PBI pin 40 should be wired to U14, Pin 14 (the MMU) .
PBI 40 is refresh output according to this wiki page.
Only PBI pin 43 'Math Pack Disable' should go to that pin 14 of U14, not both.
PBI pin 40 i wired to ANTIC pin 8 (same as MMU pin 11).
Am i right with that?
I didn't have a 74HC08 handy, but tried both 74F08 and 74LS08 without luck.
I rechecked my wiring with ohm-meter but didn't find any mistakes.
I added a 22pf cap to phi2 as i was suggested on IRC.
I also added a resistor to the CSS BlackBox i want ro run on that machine. That tip i got from Bob Wooley's stabilizer mods..
This is actually a Black Box modification. Again, due to varying phase two clock signals, a timing circuit on the
Black Box MAY need to be modified. The D1FF latch uses a R/C delay to insure the latching occurs while the bus is valid.
A late 02 signal can skew this delay, causing the latch to grab random values at times.
The fix is simple. First, locate the resistor and capacitor combo that is just below the BB's SCSI port. Look at the color
bands of the resistor. It should be brown-black-brown. Now look on the bottom side of the BB, and see if there is another
resistor soldered in the same place. If so, then no modification is needed. If you see no resistor on the bottom
IN THAT LOCATION, then solder a 220 ohm (red-red-brown) resistor across the two resistor pads.
But with no luck again. The 1200XL runs as usual, not recognizing the BB at all.
It won't either boot from the (already configured!) Harddisk nor bring up the BB menu.
When doing my Google search, i found this text on the net:
I got into the Atari when the 1200xl was released. That was
my first 'real' computer. The maligned orphan 1200xl happened to be the
best 8-bit machine Atari ever made. I've got one still and have done the
800xl rom mod, and the internal basic mod. On this particular one I tried
Bob Wooley's 1200xl PBI mod. ALLL THOSE CONNECTIONS. I double checked,
rechecked etc. I even redid the mod completely with a new set of chips and
cable. Nothing. Not 'no video'. The machine works perfectly when
connected to my Black Box or not. It just doesn't SEE the Black Box.
I haven't seen any updates to the 1200xl PBI mod and I don't think it
quite works. I think the PBI is not being selected or something. One
more line and it would work I swear....
So, that guy ran into same situation as me. I'd really
love to get that BB running, because the 1200XL board i work on is
that one in my 1250XLD, the 1450XLD remake. A Floppy on PBI plus
a SCSI HD inside would make my remake a bit closer to what Atari wanted
the 1450XLD to become. The Flagship of the XL line.
Is there someone who can give me some hints or, even better, did solve
the same situation?
Thanks for reading,
Edited by Beetle, Mon Jun 2, 2008 3:53 PM.