Coleco Pencil 2 modification?

[cdoty]

Given that there's a slim chance that I will ever see a Hanimex Pencil II for sale, and an even slimmer chance that I could afford it, I decided to do the next best thing, convert a Colecovision to a near Pencil II system.

 

The system would use a Super Game Module to supply the 2k of RAM needed by the Pencil II. I'm assuming that changing out the SRAM chips wouldn't give the Colecovision 2k, since there probably aren't enough address lines running to the SRAM. This should be closer to a Pencil II with the 16k ram expansion.

 

I currently have a BIOS working under BlueMSX. I only need to patch in a routine, of 7 bytes, to enable the SGM and change the initial jump to jump to the routine first. I'm not doing any checks for the SGM or Adam ram, since it's designed to go into a Colecovision and the SGM needs to be present for any of it to work. I'm pretty sure the $1A01 area of the BIOS is safe to use, as it seems to contain the name of a source file, which is duplicated, in lower case, below it.

 

The only potential issue I see is timing with enabling the SGM ram. I will be able to test later this week, as I have purchased a modified Colecovision with a socketed BIOS. Granted, this will not support the keyboard or cassette tape interface, but my main objective is to test out Pencil II software, that I create. The Basic cartridge does load up and accept input from the controller.

 

Are there any other potential issues I may have missed?

Edited August 12, 2020 by cdoty

[cdoty]

It works!

 

Here is it booting. I had to use a 27e257 EPROM with the modified BIOS duplicated 4 times to fill up the EPROM. I couldn't get my EPROM burner to burn a 27c64 EPROM today and an EPROM emulator didn't work in 2764 mode.

 

After that, I burned the Treasure Hunt game to another 27e257, and the boot screen started cycling, which I recognized as a memory issue from my testing in emulators.

 

Once I reseated the Super Game Module, it came to life and the game worked:

 

The controller works as expected.

 

Here is an IPS patch for the mt.u4 BIOS rom:

pencil2.ips

 

This will work in BlueMSX if RAM is added (16k or 24k at $6000) in the Machine Configuration. It doesn't emulate the Super Game Module RAM correctly, or at all.

 

It also works with the Basic cartridge, and the cartridge does recognize the extra RAM. The controller does generate some input.

Edited August 14, 2020 by cdoty

[LoTonah]

Huh.  Just read up a bit on this system, I didn't know of its existence.

Love the controllers... wonder what their inspiration was    Nice to see that they're compatible.  They actually look better than the ADAM controller, in my opinion.

Couldn't find any videos of any software running, besides booting into the BASIC and the BIOS screen.  I'd love to see what other software there was, maybe it could someday be ported?

I'd love to play around with that BASIC to see what it could do.

Edited August 15, 2020 by LoTonah

[cdoty]

Yeah, the balls would definitely make the controllers easier to use.

 

I only know of Treasure Hunt that can be found and is supported by MAME. I guess there are three others around that haven't been dumped yet.

 

[phattyboombatty]

I just dug up this thread, which I found inspiring. I am curious to find out how the Pencil II games play, and I think it would be neat to see them running on a ColecoVision. I did a quick search, but I'm not sure the ROMs have been made publicly available. Has anyone considered releasing and/or converting these for The Fun of Discovery?

[digress]

I would like to see this as a core for the collectorvision phoenix. 

 

Make it so.

[Bmack36]

2 minutes ago, digress said:

I would like to see this as a core for the collectorvision phoenix. 

 

Make it so.

So it is just a different BIOS used, otherwise everything else is the same? 

[cdoty]

9 hours ago, Bmack36 said:

So it is just a different BIOS used, otherwise everything else is the same? 

A different BIOS, and it needs 2k instead of 1k. And, it will use the SGM as extra RAM.

 

It also runs at 50hz instead of 60hz. The music plays fast on a 60 hz Colecovision.

Edited August 16, 2020 by cdoty

[cdoty]

10 hours ago, phattyboombatty said:

I just dug up this thread, which I found inspiring. I am curious to find out how the Pencil II games play, and I think it would be neat to see them running on a ColecoVision. I did a quick search, but I'm not sure the ROMs have been made publicly available. Has anyone considered releasing and/or converting these for The Fun of Discovery?

 

They seems to play fine. Both action buttons, the keyboard, and the joystick worked fine. I thought I had found an issue when Treasure Hunt stopped at the end of the game, but it was just waiting for the * button to be pressed.

 

It does run fast on a NTSC Colecovision, since the Pencil was a 50 hz PAL system.

Edited August 16, 2020 by cdoty

[Bmack36]

 

It looks like it boots up. The Atarimax won't load the games though, so that would need to be worked out.

[cdoty]

Yeah, I had to use an EPROM board for that. The Phoenix should be able to load the ROM from the SD card, right?

 

I started looking into modifying the embedded ROM in the AtariMax firmware, but it looks like it used BIOS calls.

 

If it's possible to get the source, I would be happy to modify that source to work on the Pencil II.

Edited August 16, 2020 by cdoty

[Bmack36]

Game loading is now working on the Pencil2 Core on the Phoenix

 

 

[Ikrananka]

27 minutes ago, Bmack36 said:

Game loading is now working on the Pencil2 Core on the Phoenix

Now that's very cool.  Is this a core that will be officially released for the Phoenix?

[phattyboombatty]

3 hours ago, Bmack36 said:

Game loading is now working on the Pencil2 Core on the Phoenix

Seriously cool. Treasure Hunt looks like it would have been an attractive early release for the ColecoVision, right up there with Smurf Rescue and Cosmic Avenger. I'm looking forward to discovering the fun in these hidden gems!

[retroillucid]

On 8/16/2020 at 4:51 PM, Ikrananka said:

Now that's very cool.  Is this a core that will be officially released for the Phoenix?

 

I don't see why we should not release this core 
Now, the only thing we would need is more Pencil II games to be dumped
 

[ZillaRUSH]

Treasure Hunt is great to play!  Love it!!