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Geoffg

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Joined: 06/06/2011
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Posted: 12:57am 03 Jul 2021

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bar1010 said What is the reasoning for leaving the maximum program size at 516KB when 32MB RAM is available for Generation 2?
What is the reasoning for allocating only 7MB of the 32MB RAM for video?
It seems to me that if more was allocated for video then we could have 16bit color for 1920x1080 resolution mode.

The program is stored in flash and given the ARM Cortex-M7's internal architecture that is the maximum contiguous flash available. There are good reasons for storing the program in flash but I won't go into that now.

The video resolutions and colour depth are constrained by a number of factors with the main one being the bandwidth between the RAM and processor - this is why a much faster RAM is used in the G2 design and why there are these seemingly arbitrary limitations. So RAM is not the limitation, bandwidth is.

Peter does have a good point, you seem to be implying that you could do a better job of the design. I very much doubt that.

Geoff

Geoff Graham - http://geoffg.net

TassyJim

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Joined: 07/08/2011
Location: Australia
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Posted: 01:10am 03 Jul 2021

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Mixtel90 said Can I ask what decided the value of 4k7 for the audio output resistors?

I found the posts from earlier
https://www.thebackshed.com/forum/ViewTopic.php?TID=12788&PID=158644#158644#158644
In summary,
The data sheet calls for 5k or higher for minimum distortion.
My tests show visible distortion with 1k or less.

Jim

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Mixtel90

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Joined: 05/10/2019
Location: United Kingdom
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Posted: 06:52am 03 Jul 2021

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Thanks Jim. :) I was just something I was wondering about. Those scope pics are good!

The available current from the output is actually quite limited if you want a reasonably linear output (which applies to its use as a DC DAC too). It will certainly be very limited if you want to get close to the supply rails.

A capacitor coupled source follower stage would probably be rather good for headphones, to get rid of the DC and bias the output to mid supply. It might need 100mA or so of lovely inefficient class A current for each channel though. :) I'll try that on the CMM2 at some stage. Or a non-inverting op-amp, of course. Or an op-amp of some sort (LM4880 would be nice if I can find one).

Mick

Zilog Inside! nascom.info for Nascom & Gemini
Preliminary MMBasic docs & my PCB designs

robert.rozee
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Joined: 31/12/2012
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Posted: 07:29am 03 Jul 2021

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our prime minister here in nz, Jacinda Ardern, has repeatedly urged us all to "be kind to each other". it is good advice for the 'interesting' times that we all now live in; with lockdowns and unprecedented travel restrictions, the resulting economic turmoil, mutating viruses, and an uncertain future, it is easy for us to slip into using unkind words towards each other as that is the only 'power' we seem to have been left with.

here on the backshed forums we are a diverse community, spread across the globe. each one of us faces unique pressures and challenges that other members can hardly imagine. as a result, tempers sometimes fray.

i would like to ask all to consider the feelings of others before pressing the 'send' button. please, be kind.

cheers,
rob :-)

Mixtel90

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Joined: 05/10/2019
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Posted: 07:45am 03 Jul 2021

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Be kind to each other - Couldn't agree more. :)

I'm not used to agreeing with Prime Ministers though... lol

Mick

Zilog Inside! nascom.info for Nascom & Gemini
Preliminary MMBasic docs & my PCB designs

karjo238
Regular Member

Joined: 12/10/2018
Location: New Zealand
Posts: 54

Posted: 10:33pm 03 Jul 2021

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When I get my hands on a CMM2, I'm going to be doing a lot of stuff involving controllers, so having those Wii ports built in will be a great boon.

Well done to all involved!

William Leue
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Joined: 03/07/2020
Location: United States
Posts: 381

Posted: 01:17am 04 Jul 2021

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Congrats to Geoff and Peter for making this excellent evolutionary step in CMM2 architecture! Also to CircuitGizmos and Piotr for their pioneering implementations of the Gen2 design!

I am really looking forward to writing programs for these beauties!
-Bill

Volhout
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Joined: 05/03/2018
Location: Netherlands
Posts: 3496

Posted: 10:27am 04 Jul 2021

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robert.rozee said our prime minister here in nz, Jacinda Ardern, has repeatedly urged us all to "be kind to each other". it is good advice for the 'interesting' times that we all now live in; with lockdowns and unprecedented travel restrictions, the resulting economic turmoil, mutating viruses, and an uncertain future, it is easy for us to slip into using unkind words towards each other as that is the only 'power' we seem to have been left with.

here on the backshed forums we are a diverse community, spread across the globe. each one of us faces unique pressures and challenges that other members can hardly imagine. as a result, tempers sometimes fray.

i would like to ask all to consider the feelings of others before pressing the 'send' button. please, be kind.

cheers,
rob :-)

Thank you for reminding me.
Pleas forgive me if I have upset someone with my post on the audio. I can be embarrasingly direct and short worded, not realizing we are all human and doing our best for this community.

Sincere apologies....

Volhout

PicomiteVGA PETSCII ROBOTS

mclout999
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Joined: 05/07/2020
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Posts: 430

Posted: 01:19pm 07 Jul 2021

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Hi all. I have ordered a 2ed Gen system from MicroMite.org and was interested in the ESP8266 ESP01 add-on to give me a wireless connection to my PC. I have a few questions about what I need to do to get that working when I have both of them arrive.

1. I ordered an ESP8266 ESP01S module and is that OK for this use. I did not knoww that the ESP01S was different in that it had preinstalled pull-down resistors, or an I wrong? Should I have gotten an ESP01 instead?

2. What do I need to program into the ESP01S for this to work or is the stock firmware on them all that is needed and the AT commands are what I will interact with.

3. The pictures of the standard PCB shown here show the 8 pin holes for the ESP01. Will, there be enough room for a set of female pin headers to be soldered in and the ESP01 still fit inside the case, or will I need to solder it right to the board. I would rather use the pin headers.

PS:

As far as the optional Mouse chip what needs to be done for that to be added? I have a perfectly fine 40 pin mouse cable that works for PS/2 Mouse but would love to have the USB functionality instead.

Thanks for any help you can give.

TassyJim

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Joined: 07/08/2011
Location: Australia
Posts: 5883

Posted: 09:57pm 07 Jul 2021

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mclout999 said Hi all. I have ordered a 2ed Gen system from MicroMite.org and was interested in the ESP8266 ESP01 add-on to give me a wireless connection to my PC. I have a few questions about what I need to do to get that working when I have both of them arrive.

1. I ordered an ESP8266 ESP01S module and is that OK for this use. I did not knoww that the ESP01S was different in that it had preinstalled pull-down resistors, or an I wrong? Should I have gotten an ESP01 instead?

2. What do I need to program into the ESP01S for this to work or is the stock firmware on them all that is needed and the AT commands are what I will interact with.

3. The pictures of the standard PCB shown here show the 8 pin holes for the ESP01. Will, there be enough room for a set of female pin headers to be soldered in and the ESP01 still fit inside the case, or will I need to solder it right to the board. I would rather use the pin headers.

PS:

As far as the optional Mouse chip what needs to be done for that to be added? I have a perfectly fine 40 pin mouse cable that works for PS/2 Mouse but would love to have the USB functionality instead.

Thanks for any help you can give.

The ESP01S should be OK provided the pinout is the same as the original.
It should come with the AT firmware and that should be OK depending on what you intend to use it for.
There are many different firmwares to choose from, all with different uses.

If you decide to fit a Hobytronics IC to use USB mice, it will be very difficult to go back to PS/2 mice. It would require removing the Hobbytronics chip.
This are also a couple of jumpers to solder but it is the chip that is the main thing if you elect to use it.
PS/2 mice only need a passive adapter to fit the USB socket so much simpler (and cheaper) The Microsoft Classic and most USB/PS2 mice don't even need that, just plug them in.

Edit
To give more details.
The ESP socket connects to com2 so you could also run the same programs on the CMM2 G1 using the 40 pin connector.
If you do insert the ESP module, that will tie up com2 for other use.

Similarly, the Hobbytronics chip is connected to I2C2 so you could use a Hobbytronics module connected to the 40 pin connector via any I2C lines on either G1 or G2 systems. That way, you could experiment with USB and PS/2 mice without any problems.

Jim
Edited 2021-07-08 10:30 by TassyJim

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mclout999
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Joined: 05/07/2020
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Posted: 01:27pm 08 Jul 2021

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Thanks for responding Jim. I would like to have a wireless connection to my PC for transfers and coding with MMEdit. Like I said I have a nice PS/2 mouse cable that I use but would like to free up the 40 pin connector for other things and would like a simple USB mouse connection. I can not tell from what I have found so far exactly how to install the HT mouse chip or if there are any other components that are needed to install to use it.

This is a very simple clean solution for a PS/2 mouse with that adapter added to let me use USB-PS/2 mice. I later added a overclock temp switch pigtail so I could use the overclock at will witch is no longer necessary. I need to remove that thing. I just thought about something. Will I have to rewire this because the 40 pin connector has been flipped to match the RPI pinout and key notch?
Edited 2021-07-09 16:48 by mclout999

George H
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Joined: 03/07/2020
Location: United States
Posts: 24

Posted: 03:36am 10 Jul 2021

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CircuitGizmos said Circuit Gizmos has the RetroMax version 2.3a available. Slightly different design from the CMM2 Gen 2 that Peter has made, but compatible with the firmware/software.

The RetroMax 2.3a (this is the generation 2 compatible design) is in stock at CircuitGizmos and will be shipping out around the 8th. This can be ordered with or without the "slim" case and other optional items.

If I order a Retromax from the store, is it the 2.3a version that ships? It's not clear to me (the 1.4a m/b is shown)

Thanks,

toml_12953
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Joined: 13/02/2015
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Posts: 324

Posted: 05:10am 10 Jul 2021

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Geoffg said

bar1010 said What is the reasoning for leaving the maximum program size at 516KB when 32MB RAM is available for Generation 2?

How about if OPTION RAM is used? Is there more memory available to a program then?

thwill

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Joined: 16/09/2019
Location: United Kingdom
Posts: 3831

Posted: 06:51am 10 Jul 2021

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I may have asked this before, in which case I blame the dementia, but has anyone even approached 500 kB of code on the CMM2 yet?

Best wishes,

Tom

Game*Mite, CMM2 Welcome Tape, Creaky old text adventures

matherp
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Joined: 11/12/2012
Location: United Kingdom
Posts: 8567

Posted: 07:54am 10 Jul 2021

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Quote How about if OPTION RAM is used? Is there more memory available to a program then?

No: there are lots of implementation limits in MMBasic, see the manual page 52. This is just one of them.

Geoffg

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Joined: 06/06/2011
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Posted: 08:05am 10 Jul 2021

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thwill said I may have asked this before, in which case I blame the dementia, but has anyone even approached 500 kB of code on the CMM2 yet?

I also would be interested in the answer to that.

Anyone, have you done that??

Geoff

Geoff Graham - http://geoffg.net

bar1010
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Joined: 10/08/2020
Location: United States
Posts: 197

Posted: 11:05am 10 Jul 2021

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Geoffg said

thwill said I may have asked this before, in which case I blame the dementia, but has anyone even approached 500 kB of code on the CMM2 yet?

I also would be interested in the answer to that.

Anyone, have you done that??

Geoff

I have gone up to about 320k, then encountered an error when saving the program, so took some data statements out decreasing the size to around 280k. Had around 8,700 lines of code.

thwill

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Joined: 16/09/2019
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Posts: 3831

Posted: 12:46pm 10 Jul 2021

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bar1010 said I have gone up to about 320k, then encountered an error when saving the program, so took some data statements out decreasing the size to around 280k. Had around 8,700 lines of code.

Is this a single file program ? in which case you may have reached a limitation of the EDITor and should be using #INCLUDE.

Is the size you are reporting the size of the file(s), or the "Program" size reported by the MEMORY command after the program has exited ?

My largest program to date is SAAINT at 112K as measured by the MEMORY command and that includes superflous code and many long identifiers. By contrast Z-MIM which implements a relatively complex virtual machine implementation is only 53K (or 22K when crunched).

Best wishes,

Tom

Game*Mite, CMM2 Welcome Tape, Creaky old text adventures

bar1010
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Joined: 10/08/2020
Location: United States
Posts: 197

Posted: 02:56pm 10 Jul 2021

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thwill said

bar1010 said I have gone up to about 320k, then encountered an error when saving the program, so took some data statements out decreasing the size to around 280k. Had around 8,700 lines of code.

Yes, a single file program. Yes, that is what I suspected.
The size of the file, not reported by the memory command.

CircuitGizmos

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Joined: 08/09/2011
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Posted: 02:59pm 10 Jul 2021

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George H said

If I order a Retromax from the store, is it the 2.3a version that ships? It's not clear to me (the 1.4a m/b is shown)

Thanks,

Both the Gen 1 and Gen 2 are available. For the 2.3a the option for the upgrade is shown on the side with the options for case, etc.

Micromites and Maximites! - Beginning Maximite

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