::: Area #102 (BBC Echo)
Message: #1292 (Read 9 times, has 0 replies, 4984 bytes)
Date   : Mon May 18 11:37:10 1998
From   : Jonathan Graham Harston of fidonet#2:254/27
To     : All
Subject: Subject: Running a BBC Without A Keyboard

SS> Can anyone tell me the connections required to run a BBCB without a
SS> keyboard attached?

Wow, I'd been thinking about this for some time.  I was musing on just
this point as I was downloading my mail & messages.  I was twiddling a
screwdriver to pop off a case to do some testing.

SS> I presume some electrical jiggling is required to prevent it sulking
SS> when you power up witout a kb.

No, you can't electically jiggle anything.  When you power up with no
keyboard, the startup links are 'read' as being all set, so you get
Osbyte255 set to 0.  This makes the Beeb start up in mode 0, fast floppy
speed, boot up, network priority if DNFS fitted.

SS> I intend to run several BBCB motherboards (for a control application
SS> using the user/analogue ports) linked via econet, so the econet port
SS> can be used to send any commands required, and removing kb's makes for a
SS> smaller overall system case.

That's similar to what I'm plannng.  I going to use a Keyboardless Beeb as
a sort of process server on my network.  Then I can implement an
approximation to Unix's at command - 'at 04:00 run $.MailServ.Process'.

Anyway...

When you switch on a networked Beeb with no keyboard it effectively forces
it into mode 0 and then does a *I AM BOOT.  This is all ok if you have a
server running.  You would do the following:

When a client logs on as BOOT make it run some program that checks if the
machine is one of your keyboardless clients.  You could do this by looking
at the station number - make them have numbers within a set range.  Eg, if
thay are stations 40,41,42,43 then you could do something like:

	IF EconetStation%>=40 AND EconetStation%<=43 THEN CHAIN "NoKbd"

or whatever.

Alternatively (and probably a better method), read the startup option
(Osbyte255) and if it is 0, then no keyboard is present.  The advantage of
this is that you can test you software on a keyboardful (?) station, and
simulate unplugging the keyboard with *FX255,0 then <Break>.

	IF FNbyte(255,0,255)=0 THEN CHAIN "NoKbd"

	DEFFNbyte(A%,X%,Y%)=((USR&FFF4)AND&FF00)DIV256

I would probably instead of calling NoKbd log on as another user, eg *I AM
NoKbd or something or *I AM BkGndDemon.

A problem I can see with this is that I want to have my Beeb on the same
wall socket as the server.  It takes the server (SJ MDFS) about 5 seconds
to get into Online mode.  Before this I'm sure the Beeb will have timed
out or received a 'Fileserver offline' error.  I could fix this with some
sort of electrical delay mechanism.

If you're not going to have a server, the Beebs just communicate to each
other via the network, you need to do something different. You still need
to get them to do something on startup to run the program.  If I assume
that this will be in Rom, you don't need to fetch it from disk, you just
need to start up and enter your application (presumably as the highest
priority Language rom).  Or, if you are going to store it on disk and
fetch it from there you need to do a Shift-Break from disk to get it.

I think what I'd do is write a small rom (or add some code to a rom-based
application) that checks the startup option, and then changes it to
something that will do what you want. On service call 1 (Absolute
workspace size request) do:
	.Serv1
	PHA
	LDA &28F:\ We can only be running in the I/O processor, so it is
			sort-of legal to read Osbyte255 directly
	BNE Serv1NoZero
	LDA #NewStartup
	STA &28F
	.Serv1NoZero
	PLA

NewStartUp would be, say, &FF to do nothing,. ie drop into the highest
priority language, or &F7 to boot from disk.  The full range is as
follows:

	b7:     DNFS priority: 1=DFS, 0=NFS
	b6:     HADFS drive 1 access: 1=internal, 0=external
	b5-b4:  disk speed select: 11=slowest, 00=fastest
	b3:     Reverse Shift/Break: 1=Shift-Break boots, 0=Break boots
	b2-b0:  Startup screen mode

Putting some code in rom would help with the timeout problems described
above.

I'm going to do some fuller testing of this.  I have occasionally seen a
keyboardless Beeb just hang with the cursor in the top lefthand corner of
the screen doing nothing.  However, it's managed to get into MODE 0, so it
must have read the kaybaord links by the time it's got there.

I'd be interested in following up what you're working on.

   J.G.Harston (JGH BBC PD Library) <mailto: jgh@arcade.demon.co.uk>
Expertise in: BBC+Master / Z80+6502 / CoPro+Tubes / Econet / SJ Servers
  Walkley / Planning / Environment / Highways / Transport / Devolution
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