(Getting the ANTIC to see your extra ram.)
** Should I be reading this?? **
If you are using a stock 130XE or a Rambo'ed 800XL you have no need to read any further, (other than for informational purposes). Also, CSS modified XE's are built in accordance with the modification Developing the current revision of the Wedge, I stumbled across an interesting bit of information. It seems that the 320k Peterson XE upgrades don't allow for the ANTIC chip to access extended ram. Anyone familiar with this upgrade knows that the antic enable pin of the PIA chip gets lifted from the motherboard to provide for the extended addressing needed to access the extra ram. Thus leaving the ANTIC's extended bank addressing capability untapped. This can be overcome by tying the antic and cpu's enable lines together (much the same way as it's done in the rambo'ed XL's).
Correcting this is simplicity itself, simply tie pins 14 and 15 of the socket for the PIA, together, (you know, that socket that you hopefully installed when you did your upgrade?), If not, simply run a short jumper from the pad on the motherboard that pin 15 used to occupy, to pin 14 on the same chip, (the PIA).
NOTE: From the docs I've seen, the larger Peterson XE upgrades look as if they also neglect the antic enable line. This minor mod should work just as well on them as it has on the 320k XE's.
** So what does this mean to me? **
Well hopefully you're reading this before you've run the wedge and found out that the format command bombs out in a major way. Why? because the format command uses a custom screen and display list, run out of the extended ram. Thus ANTIC, being unable to access extended ram will attempt to generate a screen from whatever data is in the main bank at those particular locations. The resultant display will usually be a blank screen, or some unreadable garbage. To address this, I've included a specially written format program, "P_FORMAT.COM". In order to demonstrate the format function to those whose machines are unable to use the Wedge's internal format command.
AND, to hopefully coerce you to perform this simple mod to your XE.
I realize, it is not normally the place of the software developer to tell users, "well, just modify your machine to use my software". However I feel most strongly, that this feature will enhance the use of your expanded XE, as well as make it compatible with future programs that may use the extended antic access. As well as with the Wedge and future Wedge Disk Accessories.
In closing I wish to thank Scott Peterson for his series of XE upgrades and in no way intend for this text to berate his fine work on the Atari 8-bit.
Ed Bachman 1-3-90.