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Looking for info to replace TRS-80 4P boot rom with 2732 eprom

VERAULT

VERAULT

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Can someone please point me in the right direction to information for using a 2732 eprom as a replacement for the stock maskrom on the trs-80 4P portable? Im told you need to add a few bodge wires and lift a pin or two to make it work.
 
From 4K and larger devices, there were slight differences in the JDEC pinouts for mask ROM and PROM. I've got tables and other information about this here. It's also worth noting that not all mask ROMs even follow the JDEC standard: typically along with the data you could also program that logic (true or negative) for the select/enable pins on a mask ROM, which might let you save a gate or two in your decoding design, and a number of systems took advantage of this.
 
I have one question. I have zero experience with model 4s. Can i just insert s model 1/3 disk and boot with power on or is there a key press combo I need. I read somewhere you need to boot a model III bios disk. So i need guidance.
 
The 4p (& 4) won't boot Model I disks. The 4p lacks the Model III ROM (which the 4 has), so your Model III bootdisk needs to contain a file called MODELA/III which is a copy of the Model III ROM. There's a link on Tim Mann's xtrs webpage to download it.

HTH, Tom
 
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hornbetw said:
The 4p (& 4) won't boot Model I disks. The 4p lacks the Model III ROM (which the 4 has), so your Model III bootdisk needs to contain a file called MODELA/III which is a copy of the Model III ROM. There's a link on Tim Mann's xtrs webpage to download it.

HTH, Tom
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I see. So if i download this file and use TRSTOOLS to insert the file into the disk images that would solve my problem?
 
One thing i noticed today was trstools seemed to only be able to open maybe one out of every 8 disk images. Even good disk images I had no problem writing to a real disk with a greaseweazle. Why is that? I can post a disk image like that if it helps.
 
VERAULT said:
One thing i noticed today was trstools seemed to only be able to open maybe one out of every 8 disk images. Even good disk images I had no problem writing to a real disk with a greaseweazle. Why is that? I can post a disk image like that if it helps.
Click to expand...
Sure - please post one of the images which wrote out a good disk but cannot be opened by TRSTools.

As for just dumping ModelA/III onto a disk, that may or may not work. The file has to be located somewhere that the boot ROM in the Model 4P can find it, and that is not always going to be where the file gets dumped by TRSTools (or any tool for that matter).
 
TRS-80.com said:
Sure - please post one of the images which wrote out a good disk but cannot be opened by TRSTools.
Click to expand...
Ok here is one for example. If I use HXC tools to convert it to a raw stream I can write it to disk just fine. Boots and plays no problem. But the disk image WILL NOT open in TRSTOOLS. I have others as well.
 

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VERAULT said:
Ok here is one for example. If I use HXC tools to convert it to a raw stream I can write it to disk just fine. Boots and plays no problem. But the disk image WILL NOT open in TRSTOOLS. I have others as well.
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Zaxxon is a copy protected disk, not a regular DOS/Non-DOS disk. Nothing should be able to open it.
 
TRS-80.com said:
Zaxxon is a copy protected disk, not a regular DOS/Non-DOS disk. Nothing should be able to open it.
Click to expand...
Hmm I guess your right about the copy protection. Here is another few that I cant do. I guess I never really thought too much about trs-80 software as having copy protection.
 

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VERAULT said:
Hmm I guess your right about the copy protection. Here is another few that I cant do. I guess I never really thought too much about trs-80 software as having copy protection.
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Hi - Those are also all self-booting or special disks. No tool is ever going to open these kinds of disks as they are not based on any DOS, nor do they have a directory track.
 
TRS-80.com said:
Hi - Those are also all self-booting or special disks. No tool is ever going to open these kinds of disks as they are not based on any DOS, nor do they have a directory track.
Click to expand...
So these disks cannot be re-written to actual floppies and can only be used with emulators?
 
hornbetw said:
The 4p (& 4) won't boot Model I disks. The 4p lacks the Model III ROM (which the 4 has), so your Model III bootdisk needs to contain a file called MODELA/III which is a copy of the Model III ROM.
Click to expand...
And specifically, it has to be in the right place on the disk. I can’t remember off the top of my head, but I think MODELA/III has to be the first file on the disk.
 
oktology said:
And specifically, it has to be in the right place on the disk. I can’t remember off the top of my head, but I think MODELA/III has to be the first file on the disk.
Click to expand...
Does trstools allow you to change the order of files on disk images? I still dont have a working disk.
 
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