[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
Re: WTD: Apple ][ Greengate DS:3 or similar
In message <20030805170009.20330.00001618@mb-m29.aol.com>, Michael J.
Mahon <mjmahon@aol.com> writes
Ah, _tape_! Tell me more about the tape! It is digital, I presume?
Perhaps a cassette? Do you have any valid tapes for it?
No, but - I can make one. I've discovered I can copy the EPROM (ROM)
sounds into the RAM locations, which I should then be able to save. I
also found my machine has 4 x the memory claimed in the manual - 256K.
It refers to sounds in 'blocks' of 2K, and given the size of the ROM for
the number of samples, and the size of some of the samples listed in the
tape library (48K for a crash cymbal), I think it might be a 16-bit
playback. I'm not sure though. Most machines of the era are 12 bit, and
in 1983 when the design was started, 8-bit was more common. AHB came at
this system blind, they had no previous experience in the market.
The tape is basically a data tape like a computer game, or synth
patches. I could make one then make a .TAP tape image from it, perhaps.
It may be possible to reverse engineer the tape format, to
enable you to write new tapes from, say, a PC sound card.
This is what I'd hoped would be possible!
BTW, have you had this machine open? If we knew more
about the microprocessor and the EPROM, it might be
possible to unravel everything about it, with enough work. ;-)
I've opened it, the only chip I could locate that looked like a CPU was
an NEC 780 - a Z80 clone usually running at 3.5MHz. Most of the visible
chips are LS logic chips, plus the 27128 and 2764 EPROMs and the memory
chips.
This would be relatively difficult to use without extensive
documentation.
Since it's Z80 based, I'm guessing it's a pure Z80 pin-for-pin. Still,
unless anyone at AHB or elsewhere has the original designs for the
sampling option, it would be next to impossible to make a replica of it.
Richard
--
Richard Kilpatrick, long haired prophet of doom. |\ _,,,---,,_
Musical suicide - www.mp3.com/RichardKilpatrick /,`.-'`' -. ;-;;,
Work: Icon Publications, Group Sales Manager |,4- ) )-,_. ,\ ( `'::.
Homepage: http://www.dmc12.demon.co.uk/ '----''(_/--' `-'\_)Morticia