Previously I gave some details about DOS-8D.
In regard of ROM boot code: There are 2 versions - simple and advanced. I'll describe shortly the advanced. In the FDC EPROM are stored:
- DRIVER to control the 16K RAM overlay;
- BOOT code.
They are used as pages. To switch use this magic pokes:
Code: Select all
POKE#380,X : RAM16K - disabled, BASIC ROM - enabled, DRIVER - activated (default state after RESET);
POKE#381,X : RAM16K - enabled, BASIC ROM - disabled, DRIVER - activated;
POKE#382,X : RAM16K - disabled, BASIC ROM - enabled, BOOT - activated;
POKE#383,X : RAM16K - enabled, BASIC ROM - disabled, BOOT - activated;
The simple version can't control RAM16K and has only BOOT code - works only with DOS-8D ver.1.xx.
DOS-8D ver.2.xx (obviously) requires the advanced version, which is emulated in Oricutron too.
The picture in
Godzil's post shows the first ever version of the hardware. It's from BOBY - the author of the DOS.
It has AmpliBus too and requires additionally real Apple FDC and 5.25 Apple floppy.
(Can you imagine 3 relative big PCB's and lot of wires
).
And here is the best ever made advanced version (1991 or so...):
The author is another BOBY (with very little help from me
)
This controller connects directly to Oric and to 5.25 floppy.
(
The picture is taken from jorodr's site. Actually this controller is like endless inspiration for jorodr to continue the making of new controllers for DOS-8D including the current Oric SD Drive!)
The BOOT code is 224 bytes and can ONLY to read the first sector from the first track at #B800 and jump there. Than this code using the BOOT code again reads the whole DOS from T00,T01 and partially T02.
Here is Track/Sector map of one empty disk (T11 is used to store file names,sizes and positions on disk).
So, I think it's possible to have custom boot sector suitable for FloppyBuilder.
The only limit is disk size: 35 tracks * 16 sectors * 256 bytes = 143360 bytes total.
Else, as Dbug mentioned DOS-8D uses RWTS exactly as Apple DOS 3.3 do.
I already disassembled DOS 2.10 and extracted the RWTS. The source can be reused in any project
(i.e. it's movable and not bound to any fixed address). The surprise is that the RWTS is bit-for-bit equal with the RWTS from Apple DOS 3.3
.
Sorry for the long post.