Date : Thu, 08 Jun 1995 09:44:09 MET
From : simon@... (Simon Mathiassen)
Subject: Hi!
From both of us to all of You!
I'm currently writing a BBC Model B emulator for MS-DOS. I skipped the Master
emulation, as i do not have sufficient information about it, neither
do i have
a 65C02 OpCode table that i trust (got three; all different). Never mind
though, as there were no software worth mentioning that required a Master.
I have a Master and an Electron, and they both run smoothly (apart from a
blown port; read later on). I have two 2*27128 ROM cartridges, where i've
plugged ADT and ExMon][ in one of them, and the other contains Kermit and an
empty socket. Trouble is that the serial port can recieve okay, but transmits
nothing.
When i started out, i had never actually touched a BBC. I had been coding on
the emulator for three months before i actually got one. If it weren't
for the
fact that the serial ports in my Master has blown, i would have ported 48 DFS
disks with games by now. Tough luck.
Anyway, i'd reckon that my emulator is about 30% finished. I have a very fast
and functional 6502 kernel written in pure assembler, a memory management
that
runs flawlessly and 80% of the 6522 emulation. I'm stuck on the keyboard and
the CRT emulation, but that's about the only things i need to finish before i
can start debugging it.
It requires MCGA (or better), approx. 80K base memory plus 20 pages of EMS
(320K), a 286 processor (or better) and an optional AdLib-compatible sound
card.
Anyway, i'm stuck about the following:
- I have no documentation at all for the Master. Has anybody considered
scanning the manuals? I have access to a MAC with a flatbed, but i haven't
got the manuals.
- I cannot port DFS disks using a PC floppy drive. No matter what, it bums
out. I've even tried to connect the BBC floppy drive to the PC, but again
without luck. It would be nice, as my emulator will mainly work with entire
disks and virtual tapes (in approximately the same format as Z80, the
Spectrum emulator, uses).
- I'm unable to emulate the 6845 on a hardware-to-hardware basis. Every
time i
try to write the register values for, say, MODE0, i get half characters
doubled on the screen.
I've read Your archives back to July, and i must say that there is precious
information contained in it, although there are too much email header
stuff. I
know what is going on around here, and i've been looking for a way to
join You
for a couple of months now. Is it possible to get the mail from February
up to
now (preferably via ftp or http)?
Here i am.
What can i offer You?
1) I have a bullet-proof way of porting ADFS floppies. You need Sydex's
ANADISK and (for Double-Sided disks) my own BQDSPLIT. If You want to rip
the files from a .BBA image (BBC ADFS disk image, used by my emulator),
You need my own AEXTRACT as well. I can make the sources available to
whoever wants them (Stony Brook Pascal+, works fine with Borland Pascal
7.01 as well).
2) I've also made Debug6502, a disassembler for 6502, 65C02 and 6510 code.
You can make a response file to load some files as default, or You can
load them from within Debug6502. The 65C02 instruction set can be
switched
on and off as the user wishes.
I will not make the source public for this one (yet), but i can XX a ZIP
archive with the EXE and DOC files and post it to whoever has interest in
it. Maybe Mark will put it on his WWW page?
3) I maintain a Norton Guide of BBC hardware info. Some of it comes
from Your
postings, but most of it (75%+) origins from the BBC literature i have.
This is also up for grabs, but give me a week to translate the Danish
parts of it into a commonly used language =) ..
4) I have 12 DFS disks and 5 ADFS disks with miscellaneous ROMs, which is
practically everything that was ever made for the BBC. You name it, and
i've probably got it lying around somewhere. These include Acorn, Beebug,
Computer Concepts, ACP and Watford's ROMs. There's also 11 ROMs in my
Master, which are dedicated Master ROMs (65C02). If only Acorn could
be as
flexible as, say, Amstrad in their licensing. Amstrad allows the
spreading
of all Amstrad and Sinclair ROMs as long as they are distributed with an
emulator.
5) I also have the aforementioned 48 DFS disks with games sorted by
publisher. It is of course illegal to copy THESE games, as many of the
software houses are still in existance. Practically i don't give a sh*t,
as one of my friends paid for *all* of these games once, and i could
easily say that i bought the originals from him, and that the porting is
only for convenient backup purposes.
Here's the standard extensions that i've come up with:
.BBR - BBC ROM image (usually 16K).
.BBD - BBC DFS image (includes 1770 and Watford).
.BBA - BBC ADFS image.
.BBF - BBC single file (unused as of now).
The emulator itself must estimate 40/80 tracks (DFS) and single/double sided
image (ADFS).
The .BBF files uses FastTracker's method of of putting the load address into
the date stamp and the execution address into the time stamp. If XModem (or
whatever) thrashes the stamps, i suggest You use ZIP to preserve them.
The literature i have:
Heiserman, David:
- Programmer's Reference Guide for the ATARI 400 / 800 Computers, Howard W.
Sams, 1984. Buggy, but it got me started.
Leventhal, Lance A.:
- 6502 Assembly Language Programming, Osborne / McGraw-Hill, 1979. Has the
best description of the 6502 available on this planet. I would not
have come
this far without it. Has 6520/6522 info as well.
Bray, Dickens & Holmes:
- The Advanced User Guide for the BBC Micro, Cambridge Microcomputer Centre,
1983. Has a LOT of good tables.
Rapier, Matthew:
- Disc Filing System manual for BBC Micro, Watford Electronics, 4th edition,
1985.
Carlos, Dave:
- The Akhter Disk Drive user's manual, Akhter Computer Group, 1985.
/* Irrelevant stuff follows */
Ferguson, John and Shaw, Tony:
- Assembly Language Programming on the BBC Micro, Addison-Wesley, 1983.
Plumbley, Mark:
- Basic ROM Users Guide for the BBC microcomputer and Acorn Electron, 1984,
Adder Publishing.
Coll, John:
- The BBC Microcomputer User Guide, British Broadcating Company, 1982. Has a
couple of nice hardware diagrams, but nothing else that cannot be found
elsewhere.
Acorn User:
- Programming tips for the BBC Micro, Addison-Wesley, 1983. Has a *bit* of
useful hardware information.
At the same time i am writing an Atari VCS 2600 emulation, since a lot of my
BBC code can be used for creating the VCS emulation (the 6507 is basically a
6502 without interrupts that can only address 8K instead of 64, and the 6532
is a very limited 6522 with 128 bytes RAM on it).
Apart from the Master and the Electron i have three PC's, a ZX Spectrum 128,
an Atari 520ST (which is currently dead) and a borrowed Amstrad NC100 (with
BBC Basic =) .. ).
I've been programming PC's for 3-4 years now. Usually it's a mixture between
Pascal (Stony Brook Pascal+ though, not the slow Borland stuff) and Assembler,
but this is my first major pure assembler project.
I am writing from the account of one of my good friends (who also happens to
be my boss), as i do not have my own E-Mail account yet. I'm planning on
purchasing one sometimes during next month, but nothing is certain.
Simon, who owns this account, is the one that made me begin coding the
emulator. He has had a BBC Model B for approx. 10 years and is pretty handy
with an ExMon if somebody cared to refresh his mind. Do not expect mail from
him unless You ask him. I think he has something to say about BBC copy
protections, though =) ..
I myself will use this list whenever necessary and possible, so feel free to
ask for help, as i will probably be doing the same.
.. And that's about it. Hope to see the flow rise a bit =) ..
Bo Krogsgaard
PS: After reading this letter i find parts of it a bit arrogant. This is not
intentional; it's just to inform You where and how i can be of help to You.
PS2: Mikro-Gen, Vortex, Ultimate and US Gold have all donated their 8-bit
games software to the Public Domain. If You want me to, i can keep You
updated
with new companies doing the same. Jet Pac for free - YES! =) ..
/-----------------------[ #include "StdDisclaimer.h" ]-----------------------\
| Bo Krogsgaard - Repairs department UeberPruegel, Computer Mail, Denmark.
|
| Leeching the account of Simon Mathiassen, simon@..., when possible.
|
>----------------------------------------------------------------------------<
| Collector of 8-bit computer emulations, lover of Californian red wine
and |
| beautiful breasts, chain smoker, coffeeholic and fanatic programmer.
|
\----------------------------------------------------------------------------/
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