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intric8
Seattle, WA, USA

Posted Sat Sep 24, 2022 2:37 pm

Over the years I've collected/purchased multiple U36 ROMs for my C128D(cr).

The U36 ROM is for an empty socket that the engineers left in the C128 in case folks in the future ever wanted to enhance their machines with programmed ROMs. What a very cool and forward-thinking idea!

Naturally, a lot of people have created some very cool enhancements for that empty socket.

The three I currently have include:
  • Super 81 Utilities
  • KeyDOS
  • GEOS 128 v2 w/ 1571
There are many others, but this is what mine can do.

Super 81 Utilities

This is a very cool upgrade for anyone with 1581 drives attached to their system.
  • It can copy whole disks from 1541 or 1571 format to 1581 partitions.
  • Copy 1541 or 1571 files to 1581 disks.
  • Copy 1581 files to 1571 disks.
  • Backup 1581 disks or files with 1 or 2 1581s.
  • 1581 Disk Editor, Drive Monitor & RAM Writer.
  • Perform many CP/M and MS-DOS utility functions.
This is generally my go-to because it's simple and easy for me to wrap my head around it. There are some that have so many features, it boggles the brain (like... the next one).

IMG_9786.JPG

KeyDOS (Antigrav Toolkit)

This ROM has so many "pro" features, it's kind of ridiculous. If you don't believe me, check out its 54-page manual! And, it is compatible with pretty much everything under the sun.

How all of this fits into 32KB is amazing in its own right.
Screen Shot 2022-09-24 at 2.21.49 PM.png
Screenshot from the manual. I wasn't about to type all of that. ;)


What's also cool about this ROM (and maybe all of these ROMs? But this one specifically explains how to do it in the manual) is that it can be installed in a Commodore REU expansion rather than the socket inside the machine. It would require a very minor mod to the PCB of the REU, but nothing super scary. Neat idea either way.


GEOS 128 v2 w/ 1571

This ROM allows for some of the GEOS boot code to be loaded from a ROM chip instead of off of a floppy. It doesn't really speed up the boot-up process that much, but it does speed things up quite a bit should you ever need to do a reboot, and other occasional processes. Obviously loading off a ROM is going to be faster than most disk reads - even compared to a 1571. However, my current setup boots off of a 1581 on Drive 9, so I'm not using this one anymore. They make a ROM for folks with 1581 drives, too - but only when set to drive 8. I can flip my drive to 8 no sweat, but it's not my preferred setup right now so I have just left things as-is.

I love my current setup so much, I plan on showing you all more about that soon.

There are several more ROMs that I'm aware of. They are:
  • Basic 8 ROM
  • File Browser v6
  • Servant 128 (I think I owned this one once but lost it)
  • Turbo Assembler
Do any of you use the U36 expansion ROMs? What's your favorite?

User avatar
BloodyCactus
Lexington VA

Posted Mon Sep 26, 2022 6:25 am

Very cool, I only have the megabit 16k/4mb rom and its amazing. Its such a cool feature to have I think on the C128

User avatar
intric8
Seattle, WA, USA

Posted Mon Sep 26, 2022 7:56 am

@BloodyCactus what software does your megabit have loaded? Is it the menu you see in the photo here?
I only have the megabit 16k/4mb rom and its amazing. Its such a cool feature to have I think on the C128
Did you buy it somewhere, or build it yourself?

User avatar
intric8
Seattle, WA, USA

Posted Mon Sep 26, 2022 8:00 am

Update: I've added a screenshot of the Super 81 utilities screen I can access with my current U36 ROM. It identifies and displays the attached drives with their IDs, which I can then use to move or copy files back and forth.

User avatar
BloodyCactus
Lexington VA

Posted Mon Sep 26, 2022 10:48 am

My megabit dates to 2010 when I got it from Dan Newbury, one of his last ones back then. When the c128 has booted up you can hit HELP key to get to the menu inside it; Its a rom chip on pcb with a wire hook for keyboard access.

It has in it;
  • Merlin 128 v1.0
  • Promos 2.0
  • My Disk Editor
  • Function keys
  • Viza Write 128
  • Viza Star 128
  • Seq Reader 128
  • Begin & End Adrs
  • Fastrac File copy
  • Directory Editor
  • Color 80 column
  • Basic Data Maker
  • Monitor 64
  • Basic Merge
  • Basic Merge +
  • Maverick File Copy
  • Maverick Track Editor
  • Single 41 Data copy
  • Dual 41 Data Copy
  • Single Nybbler
  • Dual Nybbler
  • Single 81 Data copy
  • Maverick File Tracer
  • Maverick Track & Sector Editor
  • 64K VDC RAM Test
  • REU Test

User avatar
intric8
Seattle, WA, USA

Posted Mon Sep 26, 2022 11:34 am

I've ordered a reproduction of the Megabit 128 by DC Newberry, using surface mount components (only $30). This guy also makes an internal 232 wifi modem for the C128. He's in the process of trying to build one for the C128D - the metal case is apparently a bit of a challenge for the antennae.

Anyway, very cool guy. Looking forward to checking it out!

User avatar
Zippy Zapp
CA, USA

Posted Tue Sep 27, 2022 7:49 pm

Hey I just got one on eBay for $30 too. I had been looking for an already made up one because I am way behind in my DIY projects.

User avatar
daveyk021

Posted Sat Aug 12, 2023 10:16 am

Year old thread, so I don't know if you see this or not.

I have made a U36 rom, that I can control with a switch (controlling pin 1 of a W27C512). In the lower half of the W27C512, I have SERVANT, in the upper half, I have GEOS loader.

I can not figure out how to disable the EEPROM from booting. It should be pin 20 (CE NOT). With pin 20 ground, as normal, Servant boots. When I try to pull pin 20 to 5 volts direct the EEPOM gets real hot. Damn, but it did not fail. I programmed another one just in case.

When I try to pull 20 HIGH with a 4.7K, 3.3K, or even a 470ohm, it will not pull high. It's like all the WinBond 27C512 IC have a bad CE NOT control pin. I've tried 4 of them so far. I do not have any other brand of 27C512s to try.

So if you populate U36, it will always boot whatever you have in that rom and not back to a normal boot?

User avatar
intric8
Seattle, WA, USA

Posted Sat Aug 12, 2023 11:18 am

Hi Dave,

We all see your post. In fact, I see every single one because 1) I subscribe to any responses to posts I make (meaning I get email notifications) and 2) one can subscribe to each Forum/Topic to be notified of any/all new posts and 3) when users log in, they see Orange Blocks that indicate new posts and replies have been created.

This site and community is small enough to where it doesn't produce gobs of email notifications or I'd likely not do it.

Anyway, in my own limited experience with the U36 chips, mine all boot normally by default. I have to use keyboard keystrokes on bootup in order to launch them at all (e.g. Super 81 Utilities, etc.). Ideally yours would boot "quiet" unless invoked by keystroke on bootup.

User avatar
rpiguy9907

Posted Mon Aug 21, 2023 11:44 am

I might have a BASIC 8 ROM that fits into that slot as well. Added missing commands to BASIC 7 on the 128.





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