Setting Up my ZAltair mini-FP computer ...

[Walt Perko]

Hi, 

So far with these boards:  

mini-Front Panel board  

TDL ZPU board  

FDC+ 64K RAM, ROM and Serial Drive Server board  

I can toggle programs in from the front panel switches.  

Now I want to remove the FDC+ board and replace it with a FlexRAM board and add a Martin Eberhard 88-2SIOJP board.  

The FlexRAM board should be as much RAM as possible(64K?), but not cause any conflicts with the Martin Eberhard 88-2SIOJP board.  

.

[Joseph Corda]

Walt ... 
That looks like a good start..

Did you decide what power supplies you are going to use ?
Joe

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[Walt Perko]

Hi, 

I'm using the three Mean-Wells as I have posted on my Altair 8800c build:  

http://www.brainless.org/Altair/Altair8800c/index.html

TWO: "RS-25-15" for +15V and -15V

ONE: "HRP-75-7.5" for +8V

The Mean-Well Power Supplies

You need TWO: "RS-25-15" for +15V and -15V
Digikey.com or Mouser.com or JameCo.com

and ONE: "HRP-75-7.5" for +8V
Digikey.com or Mouser.com or JameCo.com

.

[Patrick Linstruth]

You can put RAM anywhere you don’t have ROM. You typically can’t have 64K, since your ROM on the FDC+ or 2SIOJP most likely occupies F800-FFFF (2K).

The FlexRAM board would occupy 0000-F7FF giving you 62K of RAM.

On Oct 14, 2025, at 10:18 PM, Walt Perko <r4r...@gmail.com> wrote:

Hi, 

So far with these boards:  

mini-Front Panel board  

<20251013-mini-Front Panel from Terry Front-R2K.jpg>

TDL ZPU board  

<20240412-FarmTek TDL ZPU Board Repair Front-R2K.jpg>

FDC+ 64K RAM, ROM and Serial Drive Server board  

<20250328-FDC+ FarmTek #3 Front-R2K.jpg>

I can toggle programs in from the front panel switches.  

Now I want to remove the FDC+ board and replace it with a FlexRAM board and add a Martin Eberhard 88-2SIOJP board.  

<FarmTek FlexRAM 0002-R2K.jpg>

The FlexRAM board should be as much RAM as possible(64K?), but not cause any conflicts with the Martin Eberhard 88-2SIOJP board.  

<20251013-EB 88-2SIOJP board from Terry Front-R2K.jpg>

.

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<20250328-FDC+ FarmTek #3 Front-R2K.jpg><FarmTek FlexRAM 0002-R2K.jpg><20240412-FarmTek TDL ZPU Board Repair Front-R2K.jpg><20251013-EB 88-2SIOJP board from Terry Front-R2K.jpg><20251013-mini-Front Panel from Terry Front-R2K.jpg>

[Walt Perko]

Hi, 

Currently,  I'm looking for a verification for the FlexRAM DIP switch settings so that I have maximum RAM working with the Martin Eberhard 88-2SIOJP  ROMs ...

SW1      SW2      SW3      SW4      SW5  SW6  SW7  SW8
11111111 11111111 00000000 00000000 1111 0000 0000 11111100

I think I have the SW3 to SW7 correct, it's SW8 where I'm not sure what should be the best settings to work with the  Martin Eberhard 88-2SIOJP  ROMs ...  

.

[Walt Perko]

Hi,  

So the RAM DIPs should be setup as this:  

SW1      SW2      SW3      SW4      SW5  SW6  SW7  SW8

11111111 11111100 00000000 00000000 1111 0000 0000 11111100

What about the Phantom Reads and Writes?  

.

[Patrick Linstruth]

It really depends on how your 2SIOJP is configured. 

The switch settings below look good assuming your 2SIOJP is configured for ROM at F800-FFFF. 

To view this discussion visit https://groups.google.com/d/msgid/Altair-8800/905faeb6-88ce-4306-83cb-4c011fbe6792n%40googlegroups.com.

[Walt Perko]

Hi, 

So the last two switches for Phantom Read/Write are okay?  

 Yes, I have the Martin Eberhard  88-2SIOJP  ROMs  enabled.  

.

[Patrick Linstruth]

The answer is, it depends, but I think in your situation you don’t need phantom reads or writes.

An example of when you would need Phantom Reads is when using a Tarbell disk controller. The Tarbell has a boot PROM at 0000. After a reset, the PROM is enabled and it asserts phantom causing memory reads to be provided by the Tarbell PROM and memory writes to go to RAM on the Flex64K. When the Tarbell is done booting, it disables its PROM and disables Phantom so both memory reads and writes are handled by the Flex64K.

Some memory boards don’t support phantom read/write separately or phantom at all. They won’t work with a Tarbell. Another great reason to get a Flex64K.

On Oct 15, 2025, at 1:20 PM, Walt Perko <r4r...@gmail.com> wrote:

Hi, 

So the last two switches for Phantom Read/Write are okay?  

 Yes, I have the Martin Eberhard  88-2SIOJP  ROMs  enabled.  

To view this discussion visit https://groups.google.com/d/msgid/Altair-8800/cd50747b-a087-4fcd-b0cc-6b739209e2b8n%40googlegroups.com.
<20251015-FlexRAM DIPs Set-R2KT.jpg>

[Walt Perko]

Hi, 

So far with these boards in the ZAltair mini-FP computer.  I can toggle programs in from the front panel switches.  

Now I want to be sure the FlexRAM board is setup to work properly with these boards.  

mini-Front Panel board  

TDL ZPU board  

FlexRAM board  

The FlexRAM board should be as much RAM as possible (62K?), but not cause any conflicts with the Martin Eberhard 88-2SIOJP board or the other installed boards.  

.

[Walt Perko]

Hi, 

This is the setup being tested ... for some reason, the AMON monitor isn't running and I see nothing on the console from the computer ... with and without a NullModem adapter.  

https://youtu.be/fs1vQqeMx_Q

.

[Walt Perko]

Hi, 

I cannot deposit anything from F800 to FFFF ... I am able to deposit below F800 ... 

The first few BYTES in the AMON ROM in this machine look like this:  

.

[Terry Fox]

If I understand correctly...

You cannot deposit into ROM, only examine.  I think you have ROM located from F800-FFFF.

or am I wrong in how you are set up?

Terry

[Walt Perko]

Hi,

I have a FlexRAM board set for 62KRAM, saving the 2K for the 88-2SIOJP EPROM the EPROM on the FlexRAM is OFF.  

I haven’t made any changes to the 88-2SIOJP since I received it back from you ... You can see the board settings in my initial post ... and later the FlexRAM board settings.  

I don't know if the "Phantom" Read/Write might be part of the problem working with the mini-Front Panel or the 88-2SIOJP ... or have a conflict with the TDL ZPU board.  

There seems to be ROM at F800 ...  which should be the 88-2SIOJP AMON.  

.

[Patrick Linstruth]

Since you’re bringing up a new system, have you tried something simple like c3 00 00 at address 0000 and see if that runs?

It should just jump to 0000 over and over again. You should be able to single step too.

If the picture you sent of the first bytes of AMON is Examine Next, something is wrong since your address bus is not showing sequential bytes. 

Sent from my iPhone

To view this discussion visit https://groups.google.com/d/msgid/Altair-8800/f72d121f-843e-4979-933c-0da75507396en%40googlegroups.com.

[Patrick Linstruth]

Sorry Walt, I was reading on my phone. The address LEDs look great.

Your front panel is displaying the following

F800 RLC

F801 CMP C

F802 RM

F803 DI

F804 LXI H,xx60

This does not look right. The source code I have for AMON 2.4 is:

F800 LXI B,F8BC

F803 DI

F804 LXI H,FF00

The only bytes that look right are F803 and F804.

I forgot you have programmed IO. You can try entering this small program and single stepping:

0000 XRA A

0001 OUT FF

0003 INR A

0004 JMP 0001

AF D3 FF 3C C3 01 00

As you single step, your programmed output LEDs should count from FF down to 0 (I think the programmed output is inverted, I may be wrong on that, in which case the LEDs will count from 00-FF).

First thing to do is enter this program and then examine it back to make sure it got deposited ok and then single step it and make sure it is running correctly.

Again, I would start by removing the 2SIOJP and enabling the ROM your Flex64K. We need to test your system with the fewest components possible. If you want to have your first test of a new system be booting CP/M from the serial drive server, that’s great if it works. If it doesn’t, time to scale back and start with the most simple and move towards the more complicated once the basic functionality of your front panel, CPU and RAM is confirmed.

To view this discussion visit https://groups.google.com/d/msgid/Altair-8800/875BDCD1-A093-458A-800E-6D465F6192CB%40deltecent.com.

[Patrick Linstruth]

Looking at this more, let’s compare what should be at F800 - F805 to what your front panel is displaying:

AMON:

01 BC F8 F3 21 00

Your System:

07 B9 F8 F3 21 60

So it looks like you are seeing the ROM, but the wrong data is being put on the data in bus for some address locations, the ROM card is seeing an address on the bus different than what your front panel is displaying, the front panel is displaying the wrong information, or something else. I don’t see a pattern, but someone smarter may.

I am back to my original recommendation of removing the 2SIOJP and using the Flex64K for RAM and ROM until that is known to work. None of the 2SIOJP features are needed at this time. You don’t even need a 2SIOJP installed to know if the monitor is running correctly. The front panel can tell you that without a serial board installed at all.

The front panel doesn’t care about phantom. It doesn’t use it. I don’t think anything you currently have installed needs phantom. But if it makes you happy, enable it on the Flex64K. It shouldn’t hurt anything unless you have something pulling the phantom line to ground or don’t have pull-up resistors, which is why it’s better to leave it disabled unless you need it.

Maybe a good Zoom topic would be how to use a front panel to diagnose problems and how the LEDs tell the story of what is going on in the machine. I may start a Github repository of small test programs that can be entered with a front panel.

To view this discussion visit https://groups.google.com/d/msgid/Altair-8800/f72d121f-843e-4979-933c-0da75507396en%40googlegroups.com.

[Joseph Corda]

Patrick I like that front panel topic for next zoom meeting! 

Walt 

Has this flex64 card  and Amon eprom combination worked on another system?

If not,  it is possible that when burned Amon it was placed with the wrong offset in your EPROM ?

Since the front panel display at F800 doesn’t match beginning  of Amon code  it Might be worth pulling the ic and  reading it  on your burner to make sure it looks correct..and that Amon is  at the offset so it will be at F800 when read … I believe it should start  at  3800h offset  in the eprom when viewed but don’t quote me ;-)

Joe

To view this discussion visit https://groups.google.com/d/msgid/Altair-8800/C44CD3A1-C63B-47B8-B6CA-B11E23F5DDF3%40deltecent.com.

[Patrick Linstruth]

Walt, maybe we can use your current problem as an example of using the front panel to diagnose a problem.

Based on your video, there was no need need to involve TeraTerm, null modem adapters, or anything of the sort. The front panel clearly shows that Amon is not running, so checking for serial output on the 2SIO is not going to help. We can use the Zoom meeting to show why your front panel shows Amon isn’t running and possible ways to move forward to fix your problem.

Just a suggestion.