Two questions about the ROM board

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Magnus Olsson

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Apr 3, 2022, 12:17:28 PMApr 3
to PAL 6502 computer
1. Is there any free space in the PAL-1 ROM supplied with the ROM board, so I can add code of my own to it, or does the pre-programmed software fill it completely?

2. I see that on Tindie, there are different options for which type of ROM (if any) to order together with the board. What exactly is the difference between a "refurbished and re-branded 28C265"  and a "recycled 28C265"? It sounds like both are pre-used, since there's also the more expensive choice of a brand-new one, but I'm not sure of the difference between refurbishing and recycling.


Jim McClanahan

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Apr 3, 2022, 3:15:03 PMApr 3
to Magnus Olsson, PAL 6502 computer
The EPROM is split into two 16K banks and both are pretty much full. There are a few spots with some open space, but we basically kept adding stuff until we ran out of room. The source code is on GitHub and the programs in one bank are basically all memory images that are copied to RAM and then run while the other bank is programs that run from ROM.

With the gadget cards and such, it may be worth coming up with some different flavors of ROM at some point. I also need to spend more time with the EEPROM to see if it is possible to build some code that would update the contents without having to pull the chip.

Thanks,
Jim W4JBM

On Sun, Apr 3, 2022, 12:17 PM Magnus Olsson <mne...@gmail.com> wrote:
1. Is there any free space in the PAL-1 ROM supplied with the ROM board, so I can add code of my own to it, or does the pre-programmed software fill it completely?

2. I see that on Tindie, there are different options for which type of ROM (if any) to order together with the board. What exactly is the difference between a "refurbished and re-branded 28C265"  and a "recycled 28C265"? It sounds like both are pre-used, since there's also the more expensive choice of a brand-new one, but I'm not sure of the difference between refurbishing and recycling.


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Magnus Olsson

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Apr 3, 2022, 5:32:15 PMApr 3
to PAL 6502 computer
Thanks for the info! I've already had a look at the GitHub repo and there seems to be some pretty interesting stuff on that ROM!

Jim McClanahan

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Apr 3, 2022, 5:50:39 PMApr 3
to Magnus Olsson, PAL 6502 computer
My original thought was to build a version of EhBASIC that would run out of ROM. Liu really wanted FORTH to be available and pointed out that any "authentic" BASIC programs from back then would assume MS BASIC. 

Getting FORTH running was a bit of a challenge. Porting Integer BASIC was also a challenge, but felt great to get working.

I still need to clean up the PBUG source code.

Thanks,
Jim W4JBM

GN L

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Apr 4, 2022, 12:04:24 AMApr 4
to Magnus Olsson, PAL 6502 computer
Jim did an impressive work filling the space as much as possible! I think the best way to add new code is using another EEPROM chip or replace some part of Jim’s code as he said in his mail.

The refurbished chip is some kind of EEPROM with 16KB capacity, I don’t know what type and brand it actually is, the original printing was polished, and then some “brand” and “type” were etched.

The recycled chip is a used original chip.



> On Apr 4, 2022, at 12:17 AM, Magnus Olsson <mne...@gmail.com> wrote:
>
> 1. Is there any free space in the PAL-1 ROM supplied with the ROM board, so I can add code of my own to it, or does the pre-programmed software fill it completely?
>
> 2. I see that on Tindie, there are different options for which type of ROM (if any) to order together with the board. What exactly is the difference between a "refurbished and re-branded 28C265" and a "recycled 28C265"? It sounds like both are pre-used, since there's also the more expensive choice of a brand-new one, but I'm not sure of the difference between refurbishing and recycling.
>
>
>
> --
> You received this message because you are subscribed to the Google Groups "PAL 6502 computer" group.
> To unsubscribe from this group and stop receiving emails from it, send an email to pal6502+u...@googlegroups.com.
> To view this discussion on the web visit https://groups.google.com/d/msgid/pal6502/09782644-5f5e-4a30-9aac-243b53cbd9c1n%40googlegroups.com.
> For more options, visit https://groups.google.com/d/optout.

Best,
Liu

Michael Doornbos

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Apr 4, 2022, 11:13:32 AMApr 4
to Magnus Olsson, GN L, PAL 6502 computer
I was thinking about putting JMON on an EEPROM. Might make a couple of them in different configs. That’s what ZIF sockets are for right? ;-) 

Happy Monday!

MD


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Michael Doornbos
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GN L

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Apr 4, 2022, 10:42:39 PMApr 4
to Michael Doornbos, Magnus Olsson, PAL 6502 computer
Yes, that is the ZIF socket for!
And PBUG on Jim’s ROM image is forked from JMON~
Best,
Liu

Michael Doornbos

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Apr 5, 2022, 8:45:12 AMApr 5
to GN L, Magnus Olsson, PAL 6502 computer
 I’ll probably continue to use Jim’s version, but I want to try hacking it myself to learn more ;-)



--
Michael Doornbos
Imapenguin.com
Evadot.com
michaeldoornbos.com
myzenith750.com <—- yes I’m building an airplane in my garage (hangar)
828-450-7418
HAM: N4LNX 

Jim McClanahan

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Apr 9, 2022, 5:52:21 PMApr 9
to PAL 6502 computer
I shaved a lot of stuff out of JMON. Some I couldn't get to work right (like the memory test) and others just weren't going to be useful (like delays and checking writes to memories so you could program EEPROMs in theory).

Also JMON uses the normal I/O routines which mean every keystroke is echoed--it is a small thing, but that bothered me and caused problems if you accidentally press something like the ESCape key.

I did find a few minor bugs (like the memory copy routine potentially corrupting things if you had overlapping ranges) and I think Jeff incorporated all of the changed I passed to him on github.

I really would like to clean the source code up one day, but for now it is kind of a low priority.

It just squeezes into the memory I had left on the ROM if I remember right--it seems like I had to shorten some messages and make a few other tweaks to save some bytes. But if you dedicated a larger chunk of a ROM you could add more.

Thanks,
Jim W4JBM

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