88-ACR Audio Cassette Interface

Announcements about the Altair 8800 Clone including software and hardware updates.

88-ACR Audio Cassette Interface

Postby AltairClone » August 21st, 2013, 8:42 pm

I am presently laying out a small add-in board for the Altair Clone that will fully implement the functionality of the 88-ACR Cassette Interface board set. This includes the addition of a third serial port for the Clone and the audio modem for actually connecting to a cassette recorder. Connection to the cassette recorder is through two 3.5mm phone jacks on the rear panel just as it was on the original Altair.

The serial port is also broken out as another DB-25 on the rear panel so it can be used as a standard serial port when not needed for cassette I/O. The additional port can be configured as a port from the 88-SIO or 88-2SIO board. Give Timesharing BASIC with three users a whirl!

Mike
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Re: 88-ACR Audio Cassette Interface

Postby Punchcard » August 22nd, 2013, 11:56 am

Will current owner be able to add this new board or will it be available only to new version of the machine?

Do you have a timeframe as to when it would become available?

It is bringing back memories of reading/saving programs of my old Timex Sinclair ZX81 computer.

I am impressed with your enthusiasm about the Altair Clone project.

Great website!
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Re: 88-ACR Audio Cassette Interface

Postby AltairClone » August 22nd, 2013, 3:20 pm

Punchcard wrote:Will current owner be able to add this new board or will it be available only to new version of the machine?
Do you have a timeframe as to when it would become available?


The board can be installed, and the Altair Clone's firmware updated, by people who already own the Altair Clone. No soldering is required (except for a few of the earliest Clones that were shipped without the required header in place on the Altair Clone PCB).

I hope to have units to ship in the next 2-3 months. These projects are done on the side, so they take some time!

Mike
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Re: 88-ACR Audio Cassette Interface

Postby AltairClone » September 19th, 2013, 3:44 pm

The audio cassette interface boards are here! I have built the first unit and I am presently working on the firmware for the processor on the board. After the interface board is working correctly, the firmware in the Altair Clone will have to be updated to support the third serial port.

Mike

Image
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Re: 88-ACR Audio Cassette Interface

Postby AltairClone » September 20th, 2013, 4:48 pm

Bad news about the audio cassette interface. Short story: The Altair Clone firmware update to support the audio cassette interface cannot be done through the update-firmware feature built into the Clone. The computer will have to come back to me in order to update the firmware in this particular case.

The processor's mapping of hardware features to physical pins is done during the first phase of initialization after a reset. This configuration is then locked for good until another reset. The firmware update feature in the Clone runs after the hardware mapping is locked. This means that a user firmware update is not able to modify the hardware mapping. The cassette interface board, however, requires modification of the hardware mapping in order to add the third UART to the Clone.

If you're an existing customer in the U.S., shipping the computer back and forth is not that expensive. Unfortunately, it is prohibitively expensive when shipping internationally.

Mike
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Re: 88-ACR Audio Cassette Interface

Postby AltairClone » September 28th, 2013, 9:18 am

The additional serial port and the audio interface are now working with the Altair Clone!

I have booted 4K and 8K BASIC from cassette and have also written and read programs using CSAVE and CLOAD in 8K BASIC.

I have also run Timesharing BASIC with three simultaneous users by configuring the additional serial port as a 2SIO port at address 014h (as expected by TS BASIC).

I'll add a page to the website soon with pictures and more information. Feel free to contact me with any questions.

Mike
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Re: 88-ACR Audio Cassette Interface

Postby AltairClone » October 8th, 2013, 2:09 pm

The website has been updated with information about the Audio Cassette Interface for the Altair Clone. Go to http://AltairClone.com and look under "Serial I/O" and "Cassette I/O" to get started (you may need to hit "refresh" in your browser to get the new information to show).

Mike
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Audio Cassette Interface now Shipping!

Postby AltairClone » October 21st, 2013, 4:44 pm

The Audio Cassette Interface units are now shipping! Documentation and support files are available on the AltairClone.com support page.
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Re: 88-ACR Audio Cassette Interface

Postby AltairClone » March 28th, 2014, 9:10 am

If you already own the Altair Clone and would like to add the Audio Cassette Interface, you may be able to add the cassette interface yourself, or your computer may have to come back to us to install the update:

  • Altair Clone Serial Numbers before 12724: Your Altair Clone (at least the front panel) must be sent into us in order to install the firmware required to support the Audio Cassette Interface. Please contact us for return instructions before shipping us your computer.

  • Altair Clone Serial Numbers 12724 and higher: You can install the Audio Cassette Interface yourself. No soldering is required.
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