APPLE TAPEDECK SERIAL
APPLE TAPEDECK SOFTWARE
APPLE TAPEDECK CODE
APPLE TAPEDECK PC

This is important because of some of the limitations of cassette players. In fact the actual data comes from the correction signals (or phase state) of the PLL.įrequency Shift Keying (FSK) used for cassettes is also normally suppressed carrier but in the case of cassettes one of the frequencies is exactly twice the other so it is effectively transmitted carrier. For example QAM is a suppressed carrier modulation so the carrier has to be generated at the other end (read back) and it is regenerated with a Phase Locked Loop (PLL). It’s not as simple as the math might have you believe. (*) The fact that digital audio used 32kHz, 44.1kHz and 48kHz is directly related to the fact that video tapes were used to record digital audio before Compact Disc and Digital Audio Tape came along. Not to mention data loss through tape dropouts. With S-VHS you can probably go up to 40 bytes per line if you design things carefully (hint: S-VHS is good enough to record Teletext signals), but by the time you can make the video rate that fast, you’ve probably already run into problems getting the data to and through the microcontroller fast enough, and you’ll have to start dealing with wow/flutter of the tape. On a regular VHS recorder with average quality tape you can probably record 16 bytes per video line (192,000 bytes per second) which is more than the data rate of uncompressed 44.1kHz stereo digital audio like audio CD’s use (176,400 bytes per second (*)). So if you put one byte on each video line, you get 12,000 bytes/second. If you use PAL (25fps) and fill 480 lines of each frame with usable data (the rest of the lines for error detection / correction and time code) in the form of black and white video, your throughput is 12,000 video lines per second. Nowadays, generating video from data and extracting that data from video again is pretty simple using modern microcontrollers.

APPLE TAPEDECK PC

I myself had an ISA card in my PC for the same purpose but it never worked right: it kept crashing the computer even when it wasn’t in use. Posted in classic hacks, computer hacks Tagged 6502, cassette, datasette Post navigationīack in the day, there was hardware to use VHS tapes for backups, my friends had it for the Amiga (simply connect the regular video output to the VCR and connect the video output from the VCR to some hardware connected to the parallel port), It worked very well.

APPLE TAPEDECK SOFTWARE

We’ve featured a few data cassette hacks over the years, including this Commodore tape deck with an LED counter, and a tape deck emulator capable of holding an entire software archive. It’s probably true to say that has made a better cassette interface than the one you could have found on your home computer back in the day.

APPLE TAPEDECK CODE

All his code can be found in his GitHub repository. His recording device was originally a hi-fi separate cassette deck after experimenting with microcassettes, but eventually he used a data recorder designed for a Radio Shack TRS-80. This chip is designed specifically for an on-off logic output rather than the 2917’s analogue voltage output. His earlier attempts used an LM2917 frequency to voltage converter to decode tones to logic levels, but on further consideration he decided to move to the LM567 tone decoder. This made generating the tones as straightforward using his processor’s built-in tone generator, but decoding still presented a challenge. Over the years he has returned to the project a couple of times, and his original Atmel processor has been supplanted by a W65C265SXB development board based on the 16-bit derivative of the 6502. was working with some microcontroller infra-red communication projects when he saw that the same techniques could be used to produce a tape interface like those on the home computers of old. Larger programs could take a while to load, but though it was rather clunky it was a masterful piece of making the best of what was at hand.

APPLE TAPEDECK SERIAL

Serial data would be converted to a sequence of tones which could then be recorded using a standard domestic cassette recorder, this recording could then be played back into the machine’s decoder and loaded into memory as a complete piece of software. If you are of the generation who were lucky enough to use the first 8-bit home computers in your youth, you will be familiar with their use of cassette tapes as mass storage.

Apple tapedeck