Atom tapes
Atom tapes
Some files have some peculiar bits such as a missing wave or an extra bit of a wave. Does anyone know how the Atom produces the waves and if there is anything that might upset the smooth flow of waves?
Dave will you be getting round to hosting the Atom tapes that have been preserved? Is an Atom emulator in development?
Dave will you be getting round to hosting the Atom tapes that have been preserved? Is an Atom emulator in development?
Re: Atom tapes
Yes! Thanks to Charlie R ("sirmorris") my Atom now has a lovely MMC card bolted on the back, and this has given me the impetus to get all the Atom tapes transferred and archived online. Will be in touch soon if I have any questions ...Fraser wrote:Dave will you be getting round to hosting the Atom tapes that have been preserved?
- CMcDougall
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Re: Atom tapes
Arcadian wrote:my Atom now has a lovely MMC card bolted on the back


how the hell did DFS0.9+ work with that? is there hope for
a MMC version to work on an Elk or elk with Plus 1 or 3



Re: Atom tapes
There's a version of GoMMC for the Electron, which can plug in the expansion port or a ROM socket with enough space around it.CMcDougall wrote:is there hope for
a MMC version to work on an Elk or elk with Plus 1 or 3
--Greg
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Re: Atom tapes
^^ yeah, i know that
but Charlie R ("sirmorris") must have changed the MM67 MMC board to work on an Atom, so wondered if he could do a elk version, as i hate GoMMC

but Charlie R ("sirmorris") must have changed the MM67 MMC board to work on an Atom, so wondered if he could do a elk version, as i hate GoMMC



Re: Atom tapes
My ears were burning
The AtoMMC board has been developed from scratch - it's nothing like MMBeeb, the hardware and software are brand new.
My Elk went missing a long time ago now
Maybe it's time to look around for one...

The AtoMMC board has been developed from scratch - it's nothing like MMBeeb, the hardware and software are brand new.
My Elk went missing a long time ago now

Maybe it's time to look around for one...
- CMcDougall
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Re: Atom tapes
Hmm. It looks like there would have to be a plus one in there somewhere without this becoming a 'real' electronics job. I'm not a real elecronicician, I only pretend to be 

Re: Atom tapes
Is there any document about the BBCs highest cassette baud rate which is about 11000? I can't remember what it is exactly.
Re: Atom tapes
BBC Advanced User Guide, p.388:
--GregThe cassette system selects between 300 and 1200 baud using
this [ACIA] division ratio. The serial ULA is always set to 300 baud for
cassette, so division by 64 actually generates 300 baud. Division
by 16 makes it 4 times faster so 1200 baud is generated. Division
by 1 would make it a further 16 times faster, ie 19200 baud but
the cassette will not operate at this speed.
Re: Atom tapes
Does the long wave frequency become 19200? At 300 baud it is 1200 but theres 4 waves.
Re: Atom tapes
Does anyone know what the Atoms fast tape add-on does? Is it needed to use the 1200 baud rate format?
Re: Atom tapes
There are utility ROMS which offer the 1200 baud rate. I'd have to hunt around to tell you which, though.
Re: Atom tapes
I wanted to check something about even/odd parity and decided to test this at the same time for you. The frequencies stay at 1200 and 2400 Hz (+1.6%) but the ULA switches between them faster. How much faster is debatable but is definitely not 19200 times per second. The data stream is not recoverable. See attached wave file which includes source program. VLSI behaviour is practically identical. For a suitable decompressor see e.g. here.Fraser wrote:Does the long wave frequency become 19200? At 300 baud it is 1200 but theres 4 waves.
Regards,
--Greg
- Attachments
-
- casout5-ferranti.wav.bz2
- The theoretical 19200 baud tape format
- (188.28 KiB) Downloaded 73 times
Re: Atom tapes
I can't see any difference to a 1200 baud file. Is it recorded straight from a BBC? The waves are very regular and it easily converts to CSW with a baud rate of about 1201.
Re: Atom tapes
Have I misunderstood you? Is the WAV file a program to produce the 19200 baud rate?
Re: Atom tapes
The 19200 baud output follows the program, as you can see it's nothing more than a security wave.
I guess that at the start of each wave the ULA latches TxData from the 6850 and emits a whole short wave or a whole long wave then latches TxData again.
I recorded it straight from the BBC using a minidisc player as a pass-through amplifier.
Here is the program listing. It copies itself to the cassette port at 19200 baud:
Greg
I guess that at the start of each wave the ULA latches TxData from the 6850 and emits a whole short wave or a whole long wave then latches TxData again.
I recorded it straight from the BBC using a minidisc player as a pass-through amplifier.
Here is the program listing. It copies itself to the cassette port at 19200 baud:
Code: Select all
2 REM >CASOUT5
4 REM Adapted from AUG p.212-3
10 REM Fudge factor: put 2 dummy bytes in RS423 input buffer
20 REM to allow control of RTS flag by use of buffer
30 REM tolerance (OSBYTE &CB, 203)
40 *FX 138,1,1
50 *FX 138,1,1
60 REM Enable receive interrupts to allow control of RTS
70 *FX 2,2
80 REM Indicate that RS423 is cassette
90 *FX 205,64
100 REM Select baud rates
102 REM 19200 baud RX (not 300)
104 REM for Ferranti and VLSI ULAs
110 *FX 7,8
115 REM 300 baud TX as set by MOS
120 *FX 8,3
130 REM Reset 6850
140 *FX 156,3,252
145 REM Set ACIA to divide clock by 1
150 *FX 156,0,252
160 REM Turn tone on
170 *FX 203,9
180 REM Turn motor on
190 *MOTOR 1
200 REM Inform user
210 PRINT "Press record and return"
220 DUMMY=GET
230 REM Select output route
240 *FX 3,3
250 REM Send ULA synchronisation
260 VDU &AA
270 REM Wait (header tone)
280 TIME=0
290 REPEAT UNTIL TIME=500
300 REM Send data with a '*' tape synchronisation
310 PRINT "*HELLO THERE"
312 FOR Z%=PAGE TO TOP-1
314 VDU ?Z%
316 NEXT
320 REM Wait until buffer empty
330 REPEAT UNTIL ADVAL(-3)>&BE
340 REM Pause for a short period of tone
350 TIME=0
360 REPEAT UNTIL TIME=50
370 REM Disconnect RS423 output
380 *FX 3,0
390 REM Turn off tone
400 *FX 203,255
410 REM Wait (for an interblock gap of silence)
420 TIME=0
430 REPEAT UNTIL TIME=150
440 REM Turn motor off
450 *MOTOR 0
460 REM Restore RS423
470 *FX 205,0
480 REM Tidy up serial input
490 *FX 2,0
500 *FX 21,1