Disk sounds? RAM-Based MBL?

General discussions related to the Altair 8800 Clone

Disk sounds? RAM-Based MBL?

Postby toml_12953 » October 8th, 2014, 12:13 pm

Any chance of getting a speaker to play disk sounds when the floppies are accessed?
How about a version of the MBL that copies itself to RAM so it can be used when the Turnkey board is active?
How about an official weight I can put into the case to give the Clone the heft of the original? (OK, I just threw that one in :))

Probably not but it doesn't hurt to ask!
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Re: Disk sounds? RAM-Based MBL?

Postby AltairClone » October 8th, 2014, 3:24 pm

Martin Eberhard created an updated version of MBL (he calls it MBLe) that along with a few other features, is compatible with the Turnkey module. I have now posted MBLe in the ROMS directory on the support page (http://altairclone.com/downloads/roms/).

I really want the feature to play disk sounds as well! Unfortunately, the cassette interface used the last easy "hook" into the main board. Otherwise, an audio board that sits right where the cassette interface board is present would be an option. Just plug in computer speakers and listen! I guess a combo audio cassette interface / disk sound board could be built someday.

The official weight for placing inside the Altair Clone is a stack of BYTE magazines :)

Mike
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Re: Disk sounds? RAM-Based MBL?

Postby toml_12953 » October 8th, 2014, 9:08 pm

AltairClone wrote:Martin Eberhard created an updated version of MBL (he calls it MBLe) that along with a few other features, is compatible with the Turnkey module. I have now posted MBLe in the ROMS directory on the support page (http://altairclone.com/downloads/roms/).

I really want the feature to play disk sounds as well! Unfortunately, the cassette interface used the last easy "hook" into the main board. Otherwise, an audio board that sits right where the cassette interface board is present would be an option. Just plug in computer speakers and listen! I guess a combo audio cassette interface / disk sound board could be built someday.

The official weight for placing inside the Altair Clone is a stack of BYTE magazines :)

Mike


Hey, two out of three ain't bad!
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Re: Disk sounds? RAM-Based MBL?

Postby toml_12953 » October 12th, 2014, 10:21 pm

AltairClone wrote:Martin Eberhard created an updated version of MBL (he calls it MBLe) that along with a few other features, is compatible with the Turnkey module. I have now posted MBLe in the ROMS directory on the support page (http://altairclone.com/downloads/roms/).

Mike

I can't make MBLe work when the turnkey board is active. When I disable it, I can load cassette BASIC as usual but when it's active, I get no response at all. Does the address the turnkey board jumps to make any difference? I have it set to jump to the DBL.

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Re: Disk sounds? RAM-Based MBL?

Postby AltairClone » October 13th, 2014, 9:58 am

The DBL reads the sense switches as part of its initialization (it has copied itself to RAM before it reads the sense switches). Since reading the sense switches disables the ROM on the Turnkey board, the MBLe ROM is "gone."

Probably best to have the Turnkey module jump to the Turnkey ROM. You can then J177400 to boot from disk or J177000 to run MBL.

Related to this topic, Martin and I have each created versions of the Turnkey ROM that add a "B" (boot) command and a "T" (tape) command to jump to the DBL and to the MBL respectively. I also added "H" to load Intel hex files and an "A" (APE) command to boot using the "Altair Peripheral Emulator."

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Re: Disk sounds? RAM-Based MBL?

Postby toml_12953 » October 13th, 2014, 1:27 pm

AltairClone wrote:
Probably best to have the Turnkey module jump to the Turnkey ROM. You can then J177400 to boot from disk or J177000 to run MBL.

Mike

Even when I do that, MBLe doesn't read a tape when the turnkey board is active.
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Re: Disk sounds? RAM-Based MBL?

Postby AltairClone » October 13th, 2014, 5:33 pm

Interesting problem...

In your configuration, MBLe looks for the top of RAM and finds it FCFF (you have the Turnkey ROM at FD00), and therefore copies itself into RAM between FC00 and FCFF. However, the Turnkey module actually overlays a full 1K of RAM (FC00-FFFF), so when the sense switch is read, the full 1K of Turnkey address space is swapped out wiping out the re-located MBLe at FC00-FCFF.

To make it work, force a PROM at FC00:
1) Upload a PROM .hex file (e.g., DBL.HEX) to an empty PROM "slot" in the clone (label it "End of RAM")
2) Use the "Change Load Address" menu option to set the PROM address to FC00

This will make MBLe find the end of RAM at FC00 instead of in the middle of the Turnkey board.

The Clone allows PROMs to overlay RAM on 256 byte boundaries, but if the Turnkey module is enabled, I need to force FC00-FFFF to be PROM no matter what is loaded in the PROM table.

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Re: Disk sounds? RAM-Based MBL?

Postby toml_12953 » October 14th, 2014, 8:36 pm

AltairClone wrote:Interesting problem...

Mike

Oh, Magoo, you've done it again!

That was just the fix I needed. Thanks!

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