Replacement for Altair Cassette Interface

[deramp5113]

Since the Altair Cassette Interface is difficult to find - and expensive when you do - I've recently demonstrated a way to make a drop-in replacement using more readily available and less expensive hardware. See

Mike D

 

[wperko]

Hi,

Good video ... I even learned a little bit from it. We need a reproduction SSM IO-4 board.

The only thing missing with the video is a link for buying the little ACR adapter board.


.

 

[alank2]

What would really be cool would be an all in one board kit if that were possible. Also would be a benefit to be able to keep both cables at the same time. I recall looking at my old NEC PC-6001 cassette interface and the two are definitely connected together yet one could be a driver and the other drove some type of op amp I think. It has been awhile since i looked at it. Honestly though, it would be very cool to have a single board solution cassette interface.

 

[deramp5113]

The Altair Clone cassette interface modem board is available on the order page of the Altair Clone website. As noted in the EOL notice in red letters, the cassette interface is still available for sale.

Mike D

 

[Hugo Holden]

The original cassette interface board looks like a very easy one to clone an exact copy of. It would be possible to make an exact replica that would be virtually indistinguishable from the original.Including the Tin plated pcb tracks with no green coating. Compared to say an exact Dazzler clone which is much more complicated.

In the same way Processor Technology made the VDM-1 S-100 board which was basically the video system extracted from the SOL-20, they made the CUTS board which was the SOL's cassette interface on an S-100 board.

I particularly like the way they did that cassette tape interface in the SOL, it was very clever. I guess that CUTS board would also work fine in the Altair ? but I am not sure.

I was so fascinated by PT's system I wrote a detailed article on it. It has a very effective input AGC system, a super clever tone discriminator and a recover clock system based on a PLL to keep track of tape speed variations. I'm not sure how other vintage computer tape interface systems compare with it, this is the only one I have examined in any great detail, but I think it might be pretty hard to beat:

www.worldphaco.com/uploads/The_SOL-20_tape.pdf

S100 Computers - Processor Technology CUTS Board

S100 Computers

www.s100computers.com

 

[deramp5113]

Frankly, both the 88-SIO and the modem board of the 88-ACR are pretty poor designs. MITS did a much better job with the 88-UIO which fits on one board, provides an equivalent cassette interface, and also provides a 6850 serial port that duplicates the functionality of the first port on the 88-2SIO. https://deramp.com/downloads/altair/hardware/88-UIO/

Some pictures here: https://deramp.com/downloads/mfe_ar...nd Boards/00-MITS/10-MITS S100 Boards/88-UIO/

 

[wrljet]

Frankly, isn't most of the Altair "pretty poor designs"?

 

[Hugo Holden]

I wonder what is in the Demodulator box labelled "D" on the 88-UIO schematic that processes the tape play signal , or what that looked like on the actual board, a custom module perhaps ?

 

[hmb]

I wonder what is in the Demodulator box labelled "D" on the 88-UIO schematic that processes the tape play signal , or what that looked like on the actual board, a custom module perhaps ?

The IC labelled "D" on the 88-UIO schematic is an LM565CN PLL.