Sinclair ZX80 / ZX81 / Z88 Forums

Pokemon, I was not aware that the P file format does not have the program name in it. I'll just take the file name it was saved as without the .p. Is there any references out there on the format of the various file types such as .p .81, etc? The SD routines I'm using only permit the DOS 8.3 format d...

The Nocash site state "The duration of the silence between each bit is 1300us" that is what I mean as a pause between bits. Also I have been doing most of my comparing using Audicity and matching up a wav file generated by Miguel Angel's conversion program with the recorded output. An Oscilloscope w...

The Nocash site state "The duration of the silence between each bit is 1300us" that is what I mean as a pause between bits. Also I have been doing most of my comparing using Audicity and matching up a wav file generated by Miguel Angel's conversion program with the recorded output. An Oscilloscope w...

I am currently working on a SD card reader that converts a P file to audio output using a Propeller Microcontroller on an Activity Board http://www.parallax.com/product/32910. I have hooked it up to a ZX81 and had it reading in the 1K Slot program. It seems to read it well until it gets 3/4 the way ...

I posted my new idea on the Parallax Propeller forums to get advice from some of the video gurus on the site. The response was that it would be very difficult since you have a window of time to do 4 Propeller assembly instructions per pulse detection. Also some sort of external synch detector needs ...

I was rereading this thread I had an epiphany. Instead of using an ADC chip why not just use a simple op-amp voltage comparator with the output tied to a transistor to switch the proper logic voltage levels. The comparator would have to be set high enough to have the back porch in Rev 3 be considere...

Yes, I believe a similar FPGA was used to make a complete ZX81 on it so I could recreate one or at least a modified ULA with it. FYI: There is a thread on the Parallax site that has a group of people making a CPM Z80 minimalist system. Right now it consists of a Z80, 32K SRam and a Propeller. The li...

Sir Morris that is exactly what I was planning. I was afraid the easiest way was to use some logic gates to be a trigger for the proper IOREQ conditions with some tricky coding. I do have a small FPGA board that I've been having some trouble getting going that probably can handle this and more. I'll...

I was thinking of interfacing a micro-controller board to the ZX81 directly so I could emulate a keyboard. Even with any of my 80-100MHz boards I noticed the timing was too slow to be read/write with an IOREQ without pulling WAIT low. I noticed timing is critical in the video routines so would pulli...

I am SOOOOOOOOOOOOOO embarrassed. :oops: Gozzo, you are right about the connectors. I picked up a cable I had mistakenly packed up with the TS1000. It had left and right audio terminating with red and white phono plugs on each end. It did plug into the TS1000 but was the wrong plug! When I used a ca...