Cassette Interface now works!!

What have you built or do you want to design to go with your replica 1

Cassette Interface now works!!

Postby vbriel » Jan Tue 02, 2007 3:51 pm

Ok, I've been working on this for a while and put it on a shelf, now I've taken it out and been working on it for a couple of days. Good news is I have the cassette interface working! This has been a major thorn in my side for 3+ years now!

I'm going to run larger tests but here is the result of my minor test.

Equipment:

Replica 1 SE and replica 1 revision C
slot expander 1 board with 3" 40 pin cable
prototype cassette interface from 2004
1 3.5mm Stereo cable m/m 3 feet
1 Radio Shack TRS-80 CCR-81 Computer Cassette Recorder

simply typing in:
1000:1 2 3 4 5 6 7 8 9 A B C D E F

then C100R
then storing the address range:
1000.100FW

I can zero out the data and reread it with the cassette interface with success.

Phase 2 of the testing will be conducted today:

Large scale storage of software programs 4K in length.

Reloading programs from tape into memory and verifying the contents.

This will not be nearly as nice as the CFFA1 board but it is another means for storage. For those wanting authentic feel, this will do it for sure.

Vince
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Postby vbriel » Jan Tue 02, 2007 4:09 pm

Ok, tried the replica 1 cassette board with Lunar lander and it loads and plays perfectly! I'm not sure why I had so much trouble in the past getting this to work. I'm going to start trying different power supplies, cables, etc and see what I come up with.

Vince
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Postby vbriel » Jan Tue 02, 2007 11:13 pm

Here is what the final prototype will look like. The real major difference is the 28C64 in place of the 128 byte PROM's. Other than that, I kept the layout as close to the original as possible.

http://www.brielcomputers.com/files/cassette.pdf

If you see something you don't like, let me know soon.

Vince
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Postby vbriel » Jan Thu 04, 2007 7:19 pm

Ok, I had to post these. There was a simple article/letter in the Apple 1 users group called audio apple. It made sound through the cassette interface.

I read this and thought, it probably sounds like crap. Well, the code had errors (may still have some) and I found them with Krusader and compiled it and ran it.

Here are the two different samples I made:

http://www.brielcomputers.com/files/audiorandom.mp3

and

http://www.brielcomputers.com/files/audiorange.mp3

Yes folks, the replica 1 has sound!! I'll post more information later.

Vince
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Postby cheese1113 » Jan Sat 06, 2007 12:33 am

Wow! Great job Vince, I want one!
Last edited by cheese1113 on Feb Tue 13, 2007 11:20 pm, edited 1 time in total.
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Postby vbriel » Jan Tue 09, 2007 5:48 pm

Ok, definately you need some type of amplified audio signal. This is obvious when you attempt to play back a recording from a PC that has no amplified output. The cassette interface has an LED that when it is receiving data, the LED glows bright. Now, when you try to playback through the PC, you can't even get a dim glow from the cassette interface. I've also tried a small portable CD player that has both audio out and headphone jack. This one I want more time with because I almost got a signal back. I recorded to CD from an old original tape wav file and tried to play it back through the CD player. I was able to get a little bit of data so there may be some hope of playing back through an ipod or mp3 player.

Vince
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Postby daustin777 » Jan Tue 09, 2007 11:37 pm

So,will a preamp circuit on input solve the problem?
--David Austin-- replica 1 se, CFFA1, MicroKIM, [kits]
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Postby vbriel » Jan Tue 09, 2007 11:58 pm

Yeah, if you mean going from PC out to preamp to input of cassette, yes. Or if you have an old PC with an original SoundBlaster 16, they had both output and powered output with a small amp onboard.

Cassette is fun to play with if you want that "vintage" feel. I'm just getting spoiled beta testing the CFFA1 card. 1 second to load is just to fast.

Vince
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Postby vbriel » Jan Thu 11, 2007 1:11 pm

Image

How does it look?

Vince
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Postby mcphja2 » Jan Thu 11, 2007 6:17 pm

Looks Great! I can't wait for production!

Now to dig through storage to find that old Radio Shack tape deck.
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Postby daustin777 » Jan Thu 11, 2007 10:47 pm

Looks great, can't wait!
--David Austin-- replica 1 se, CFFA1, MicroKIM, [kits]
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Postby vbriel » Jan Thu 11, 2007 11:36 pm

Notable things:

1 caps on all the IC's to reduce noise (surprised Woz didn't have them on the original)
2 Large LED now replaced with smaller T1 LED (brighter)
3 Radio Shack 3.5mm jacks are different then Jameco's and so mounting hole is too small.
4 74LS10 does NOT work, as a result I've sat on this project for over 2 years. Standard 7410 does however put out strong recordings.

Early estimates were wrong on pricing, looks like I might be able to produce assembled boards for $59 and kits for $49!

Low cost amplifier idea:

$5 PC speaker, open casing, cut speaker, connect 3.5mm jack where speaker was and connect to FROM TAPE on cassette interface. Plug regular end into speaker out on PC or Mac and that should work as a low budget amp. This could possibly cause damage to cassette but it would do the trick.

One nice feature Woz put into the design was a LED light and a 10 second header on the program recordings. So, enter routine to start reading from tape press play on tape player but don't hit return until the LED lights up. No rush, you have 10 seconds to press play! As soon as the LED comes on you know the header is being played. Works every time so far.

Vince
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Postby vbriel » Jan Thu 18, 2007 8:55 am

For those following the progress of the cassette interface I just ordered a final protoype run before I can do a production run. The changes were small, some aesthetic changes, and I needed to make the thru holes larger for the 3.5mm audio connectors.

Once I have the final prototypes up and running I will test them out fully before I start taking preorders.

Keep in mind the cassette interface does not compare to the CFFA1 card. It is clunky, and I have already found issues with using different tape drives, and even different models of replica 1's and getting the data to load. But it is a simple solution for mass storage.

Vince
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Postby daustin777 » Jan Thu 18, 2007 10:50 pm

vbriel wrote:
Keep in mind the cassette interface does not compare to the CFFA1 card.


I think I'll get both. Cassette for the old-school fun and CFFA1 new-school storage for old-school code.
--David Austin-- replica 1 se, CFFA1, MicroKIM, [kits]
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Postby vbriel » Jan Fri 26, 2007 8:59 am

I'm receiving what I hope to be the final prototype run of cassette interface boards today. After they have been fully tested, I will start polling for enough interest to do a run of these boards. If there is enough interest in doing a run, I will start taking preorders. Once the number of preorders hits 15 I'll start production (2-4 weeks).

So far the only issues the cassette interface has is:

1. Requires -12V supply so ATX or AT for older replica required.
2. Requires a cassette deck or some type that can amplify the audio on playback.
3. Can be flaky just because the technology is 30 years old!
4. CPU can make a difference. Most replica 1's have Rockwell or WDC 65C02 I tried a 6502 from IIe and it had a clipping noise when recording.
5. PC to replica 1 playback won't work unless your sound card is powered. Standard audio out is not and won't give enough volume to cassette interface.

Remember, the cassette interface is a great way to make the replica 1 feel vintage but it is nothing compared to the CFFA1 card. If you want a nostalgic experience, the cassette interface is the way to go. If you want efficient, mass storage with ease, the CFFA1 is the way to go. I personally have both on my replica 1 and they work great together. The CFFA1 was designed to work with the cassette interface and it does its job well.

I'll post results and pictures as soon as I can.

Vince
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