ClausB Posted August 10, 2008 Author Share Posted August 10, 2008 A look at the RAM cards showed 4K in slot 1 and 16K in each of 2 and 3. Both sizes used the same circuit board, dated 1978. They contained standard 4K or 16K DRAM chips and had jumpers to select the size. This was unlike the later 8K and 16K cards, which used different circuit boards and selected RAM in units of 8K. Looking at the Atari 800 OS Manual and Listing, I noticed that the routine that figures out total RAM size does so by testing memory in 4K blocks. Shades of the prototype hardware? The OS Listing shows evidence of the old prototype's memory map. There are these strange comments on page 78: ; "A" CART. ADDR'S ARE A000-BFFF (36K CONFIG. ONLY) ; ; "A" CART. ADDR'S ARE B000-BFFF (48K CONFIG. ONLY) ; The first one gives the correct address range for the "A" (left) cart but refers to the old prototype 36K RAM size. The second one refers to the production 48K RAM size but give the wrong address range. In the 1st post, notice that the prototype left cart range was $B000-$CFFF. Maybe these comment lines were hastily edited when the memory map changed? 3 Quote Link to comment Share on other sites More sharing options...
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.