Re: Zip Chip programming info / disk image?

[bieling@terra.es (Jorge Chamorro Bieling)]

RedskullDC <RDC@oz.org> wrote:

> 
> One thing that doesn't appear to be covered is whether it co-exists
> with DMA capable devices?
> Does it actually work with DMA devices? If so, I assume it would
> invalidate all entries in the tag/cache memories after it sees a DMA
> transfer (phase 0 clock input to the zip-chip being held low temporarily?)
> 
> I don't have any DMA cards, so this is no big deal to me, but I guess it
> could be for those with DMA scsi cards etc. who may like to build one
> of these.
> 
> It would be reasonably easy to replicate the register set that the
> zip-chip uses, but the whole tag ram scheme seems somewhat limiting.
> 
> Ideally, I would like to never write to Apple2 main memory at all, only
> to addresses within $C000-$CFFF, and even then some of those could
> be intercepted (such as a PS/2 keyboard driver, for the PS/2 keyboard
> interface haning off the FPGA board.)
> 
> The 50ms slow-down timer seems like a good idea to maintain compatibility
> with normal apple peripheral cards: disk2 , SSC etc.
> 
> Applesoft/Integer/Language Card/Main Mem can all be in a 12ns
> SRAM hanging off the FPGA.
> Initially, writes to the text/gr/hgr pages would have to go to the main
> board,
> until VGA drivers are working, then they can go off to the SRAMS
> aswell.

Hmm, things going into to this board:

1-Video generator
2-MLB RAM
3-ROM
4-Aux RAM/Language Card RAM
5-Keyboard

Things that remain in the Apple2 MLB:

6-Game paddle interface
7-Cassete i/o
8-slots

Both 6 & 7 can (should ?) be easily moved to this board too, and then,
the apple2 MLB is there only for the slots ?

This is more than a ZipChip clone, it's a complete slots-less MLB.

The question is should the slots be kept out of this MLB or not ?