Tom_Klok@mindlink.UUCP (Tom Klok) (02/05/91)
> umhild11@ccu.umanitoba.ca writes: > > This isn't really true. Many years back OSS (does ANYONE remember these guys > besides me?) put out several language carts and such that were 20 or 24k > even. Best of all, none of those carts took up more than 8k of address space. > > Lately, developers have taken this even farther. SpartaDOS X is a 64k cart > that also consumes 8k at most (when it uses anything at all). Even Atari > finally acknowledged that this could be done and produced several games > cartridges. The largest one I ever heard of was Flight Simulator II, which > was put on a 128k cartridge. Supposedly the maximum is 256k. Maybe I don't > know all the restrictions, but it seems to me that they should be able to > make a 1M cart. > Of course, what do you do with a Meg on this machine? Use it as a ROMdisk, of course. :) Like Sparta X's CAR: device, for example. Files that rarely change, like executables, would be quite happy (and fast) loading from ROM. A cardridge can't span more than 16K of address space, but by using bank selection the size is unlimited. The only practical limit is the ROM technology and how many chips you can cram into a cardridge case. Executing from bank selected memory can involve a few little tricks. Switching banks while running in a bank can cause very interesting results. Either some sort of ladder-like flipper is coded in the cardridge, or (better) a bank flip dispatcher is copied down into RAM. Flipping usually involves writing to a memory location. It's clean to decode the cart's own address space for this, or some use the (I believe) $D5xx select line. Say, for argument, you've got an 8-bit latch on the cardridge. Writing to $A000 (the bottom of the 8k cart) writes into the latch. The cardridge sits in an 8k address space, so it must use A0-A12. The latch supplies A21-A13, which gives us an easy 2MB of space. Make that a 16-bit latch, and the limit suddenly becomes 512MB. You want a BIG cardridge? :) Tom Klok a344@mindlink.UUCP
umhild11@ccu.umanitoba.ca (Jeff 'Zar' Hildebrand) (02/05/91)
In article <Ibf8poa00Uh783YxBO@andrew.cmu.edu> mg20+@andrew.cmu.edu (Michael Paul Greelish) writes: > >[ stuff about mule that I'm not interested in right now...] > >BTW, cartridge games can be only <16K due to the 8-bit's architecture... >pretty wimpy, considering some ST games require 1Mb (that's 1024K!) > This isn't really true. Many years back OSS (does ANYONE remember these guys besides me?) put out several language carts and such that were 20 or 24k even. Best of all, none of those carts took up more than 8k of address space. Lately, developers have taken this even farther. SpartaDOS X is a 64k cart that also consumes 8k at most (when it uses anything at all). Even Atari finally acknowledged that this could be done and produced several games cartridges. The largest one I ever heard of was Flight Simulator II, which was put on a 128k cartridge. Supposedly the maximum is 256k. Maybe I don't know all the restrictions, but it seems to me that they should be able to make a 1M cart. Of course, what do you do with a Meg on this machine? > >______________________________________________________________ >|\ /| >| \/ | ike Greelish >Carnegie Mellon U. undergrad, professional writing major >quote: "Everything is broken." ---Bob Dylan >stupid disclaimer: My opinions are. Jeff -- +---------------------------------+--------------------------------------------+ |"I am not *temporarily* insane." | umhild11@ccu.umanitoba.ca | +---------------------------------+--------------------------------------------+
parsons@matt.ksu.ksu.edu (Scott S Parish) (02/06/91)
umhild11@ccu.umanitoba.ca (Jeff 'Zar' Hildebrand) writes: >cartridge. Supposedly the maximum is 256k. Maybe I don't know all the >restrictions, but it seems to me that they should be able to make a 1M cart. >Of course, what do you do with a Meg on this machine? The real trick with having a 1M cart would be arrainging the code so that only 8/16k would be 'visible' at one time. But (sigh) we'll never know if it can/will be done as there is hardly anyone left to do it. -- ============================================================================== Scott Parish Internet: parsons@matt.ksu.ksu.edu (I have nothing to say.) Bitnet: parsons@ksuvm ==============================================================================