Disable ROM?

Discuss construction, troubleshooting, and operation of the Altair 8800c computer

Disable ROM?

Postby toml_12953 » June 12th, 2020, 5:43 pm

Is there a way to have the ROM disabled after an IN from port FF? I'd like to keep my AD similar to my 8800c which allows this.
If it doesn't have a way to do this would it be possible to add it?

Tom L
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Re: Disable ROM?

Postby AltairClone » June 12th, 2020, 7:31 pm

No, there is no way to do that with the FDC+. There is also not a reasonable mod to the board to provide that ability. The MITS Turnkey board provides that feature and that is the board the AD emulates to provide that capability. Martin’s 2SIOJP also implements that feature along with several other of the Turnkey board functions.

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Re: Disable ROM?

Postby toml_12953 » June 12th, 2020, 8:50 pm

AltairClone wrote:No, there is no way to do that with the FDC+. There is also not a reasonable mod to the board to provide that ability. The MITS Turnkey board provides that feature and that is the board the AD emulates to provide that capability. Martin’s 2SIOJP also implements that feature along with several other of the Turnkey board functions.

Mike


I wasn't clear. I was talking about adding the ROM disable capability to the AltairDuino not the FDC+. I have both the 88-2SIOJP and the FDC+ in my 8800c and have disabled the EPROM on the FDC+ and enabled ALTMON on the 88-2SIO which is disabled when BASIC starts. I'd like to be able to do that on the AltairDuino as well.

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Re: Disable ROM?

Postby AltairClone » June 12th, 2020, 10:14 pm

You can enable the Turnkey board in the Altair Clone, so I’m sure it could be added to the AD as well (if it’s not already in there). Ask Dave Hansel about it - he wrote the code used in the AD.

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Re: Disable ROM?

Postby toml_12953 » June 12th, 2020, 10:28 pm

AltairClone wrote:You can enable the Turnkey board in the Altair Clone, so I’m sure it could be added to the AD as well (if it’s not already in there). Ask Dave Hansel about it - he wrote the code used in the AD.

MKKE

Yes, you're right. I missed the turnkey part in the Clone manual somehow. My ultimate goal is to get the Clone, AltairDuino and 8800c to work as alike as possible.

Thanks for your reply!

Tom L
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Re: Disable ROM?

Postby toml_12953 » June 13th, 2020, 10:21 am

OK, I have an FDC+ and a 2SIOJP in my 8800c. I'm trying to automatically jump to AMON on the 2SIOJP. I get no response from the system. I put zeroes in the three front panel locations VDIP #1, VDIP #2 and VDIP #3 so I know the front panel isn't interfering. I have the switches set as in the photo. Can anyone see what I'm doing wrong?

https://www.dropbox.com/s/tgd6iy7f9g3jk8g/2SIOJP.jpg?raw=1
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Re: Disable ROM?

Postby AltairClone » June 13th, 2020, 5:31 pm

Looks like you need to turn on the “Jump Start” switch on SW3. Also, since you have a front panel machine, you should turn off the “Sense Switch Enable” switch and remove the MWRITE jumper. I can’t see your reset/POC jumpers clearly to see if that is correct. Hopefully you’ve got a local copy of the manual for the board you can refer to to see what else may need to change. It’s a very configurable board. Right now the manual is missing from Martin’s folder on DeRamp.com.

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Re: Disable ROM?

Postby toml_12953 » June 13th, 2020, 9:15 pm

AltairClone wrote:Looks like you need to turn on the “Jump Start” switch on SW3. Also, since you have a front panel machine, you should turn off the “Sense Switch Enable” switch and remove the MWRITE jumper. I can’t see your reset/POC jumpers clearly to see if that is correct. Hopefully you’ve got a local copy of the manual for the board you can refer to to see what else may need to change. It’s a very configurable board. Right now the manual is missing from Martin’s folder on DeRamp.com.

Mike


No combination of switches seems to start AMON. I even tried both methods of disabling RAM by setting the switch and putting a jumper on PHANTOM. Fortunately your front panel allows me to jump to F800. That starts AMON ok. The ROM disable works, though. Once I start BASIC, I can peek and poke into the last 2K bytes of RAM.
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