The tape loader part of SPONZY did not work with a real hardware - as it was also reported by Siggi.
So I decided to study our favorite from this perspective. The by-product of this work is in the attachment.
The basics of the hardware:
Due to the hardware solution of Zeddy's EAR-port, it is easier to produce a short, well-detectable pulse, than a longer, stable signal with well-measured length. If we have a lot of the latter in sequence, the signal is considerably distorted due to the input capacitor.
A possible solution is the amplifier recommended by Xavi, or...
The stable state of the input is the '0' (ie, the silence), into which it quickly returns after the above-mentioned short-pulse.
Why does not the interval between these short pulses carry the information?
I tested this feature and got a positive result!
The basics of the software:
A ZX81 program can not use the entire RAM area, because the ZX81-OS needs 66 bytes under RAMTOP to start the program. In which the top 4 bytes (ERR_SP and the $3E00 signaling the end of the RAM) can not be modified.
So, we have 62 bytes for fastloader!
The final result:
As in the OTLA project, a WAV file that contains 2 sections is to be produced.
The first part is for the auto-starting fastloader, and the other is for the program coded in the above described format.
The "hlg4zeddy.exe" implements this hybrid solution. Just choose the ".P" file, then the".WAV" will be created (in 44100 or 22050 samples/sec format) - see
http://www.youtube.com/watch?v=f4ef-XTxC0U.
Advantages:
- easy to create;
- easy to load (LOAD "");
- quick (1K ~5sec; 16K ~26sec);
- does not need an external amplifier (according to my experience);
- the fastloader part runs directly under the RAMTOP.
Disadvantages:
- not as fast and flexible as the ZXPAND;
- the fastloader part runs directly under the RAMTOP.
If you have 16K+ of RAM:
- but the M1NOT-circuit is not implemented, the highest value for RAMTOP could be 32768
(POKE 16389,128; POKE 16388,0)
- and the M1NOT-circuit is implemented, the highest value for RAMTOP could be 49152
(POKE 16389,192; POKE 16388,0)
Enjoy
Zsolt