“Was isolated from 1999 to 2006 with a 486. Built my own late 80s OS”

Re:“Was isolated from 1999 to 2006 with a 486. Built my own ... by dmpk2k on Monday December 15, 2014 @12:47AM (#8750830)

I think the Dragon 32 really did only have 32KB RAM, but yeah, the full 32KB wasn't typically accessible. Part of it went to video RAM, and part of it went elsewhere, so quite a bit less was available to use by default.

However, there was some hackery you could do to get close to usable 32KB for your program, although I never did that. My tape drive never worked properly, so my programs were naturally very short…

When I graduated to a 286 (in the Pentium era), that was a pretty special moment. It had a 42MB HD!

[ Parent | on HN ]

Re:“Was isolated from 1999 to 2006 with a 486. Built my own ... by jacquesm on Monday December 15, 2014 @03:23AM (#8751093)

Just poking around in the video chip would enable the second bank of 32K RAM for writing. Then copying the basic ROM by reading the ROM and writing the RAM would make it possible to switch to the next stage, which was to enable the second bank of RAM for reading and writing.

After that a relocation routine took care of moving the ROM code to the upper portion of the RAM which left you with 48K of usable RAM in BASIC and 64K - the video mode you were using for assembler!

[ Parent | on HN ]