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PIM-TB10 27256 rom bios

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MV75

Experienced Member
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May 9, 2010
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114
Ok, I have this socket empty on my board and want to know if it's as simple as getting a 27256 chip and then programming a rom bios to it and off it goes. ?

The chip is no problem to find, futurlec (where I've been getting most of my components from) have a list of three, but I have no idea on where to get the code from to program it.

Thank you to anyone that can decipher that mess. :)
 
I have a PIM-TB10-Z.
The User Manual for it is at http://members.dodo.com.au/~slappanel555/manuals.htm (slow web site).

It's not clear from your post which of following is the case:
1. Your motherboard is missing the BIOS ROM, or
2. Your motherboard is working but you want to add a ROM to the empty U49 socket.

In case you lack the BIOS ROM:
The BIOS ROM is a 2764 and a string within it's contents is, "DTK Corp. COMPUTER '88 DTK/ERSO/BIOS 2.42 (C) 1986"
A copy of that BIOS is at http://members.dodo.com.au/~slappanel555/bios/DTK_ERSO_2.42_2764.zip

If you are after the BASIC ROM that fits into socket U49, I don't have that.
 
#2 option please. :)

I have the manual and I actually got a v20 cpu for it today and it's working fine. :)

I want to add the 27256 chip with rom basic(a), and just want to know if it's as a simple affair as buying a 27256 chip and flashing a basic(a) rom image to it, if so, where could I find the rom image to do so? Thanks.
 
MV75 said:
I want to add the 27256 chip with rom basic(a), and just want to know if it's as a simple affair as buying a 27256 chip and flashing a basic(a) rom image to it, if so, where could I find the rom image to do so? Thanks.
Click to expand...
If you can find a suitable image, then yes, it will be as simple as burning the 27256 EPROM then placing the EPROM in socket U48 (designed for 27256).
 
modem7 said:
If you can find a suitable image, then yes, it will be as simple as burning the 27256 EPROM then placing the EPROM in socket U48 (designed for 27256).
Click to expand...

Caution: the two ROM sockets are for 32k memories and mapped to F000 and F800. IBM's ROM BASIC takes up all of both chips except for the 4k(?) ROM BIOS at the high end of the high chip. YMMV with a different version of BASIC but, AFAIK, the entry point for BASIC from the BIOS is at F600.
 
mkemp said:
Caution: the two ROM sockets are for 32k memories and mapped to F000 and F800. IBM's ROM BASIC takes up all of both chips except for the 4k(?) ROM BIOS at the high end of the high chip. YMMV with a different version of BASIC but, AFAIK, the entry point for BASIC from the BIOS is at F600.
Click to expand...

Indeed, this presented problems for the autors of the IBM 5170 BIOS. If you look at the ROM images, you'll find that the BIOS code is "split" with an upper and lower part sandwiching the BASIC interpreter.
 
I have extracted and combined content of two EPROMs from a 286. What does an entry point for BASIC look like ? At address F600 (7600 in 27256 type EPROM) it looks like this:

31FFB001A2A904E86200A0A904FEC87403E91FFF53E80D057503E88C125B4BE8FBF85E87DE568A073C2C748B5B4BE8ECF80AC05B7403E90AFFC6072CEB06538B

Well it is not working. BIOS says: no ROM BASIC found.
 
archeocomp said:
I have extracted and combined content of two EPROMs from a 286. What does an entry point for BASIC look like ? At address F600 (7600 in 27256 type EPROM) it looks like this:
Click to expand...

Excuse me? Can you explain how a physical address of F600:0 (F6000) translates to an EPROM address of 7600?
 
You are right Chuck as ever. I was wrong. I have TurboXT with two sockets. One 2764 for BIOS. That one is probably mapped to F000:E000. And BASIC socket is 27256 type. It should then be mapped to F000:6000. And this will translate to 0000 EPROM right ? I only own PC/XT for few months, and I am learning here from forum ...
Chuck have you ever seen BASIC for 27256 EPROM ? Even modem7 does not have such image :)
 
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Well, the simplest thing would be to take the contents of the 4 BASIC ROMs from the 5150, concatenate them and burn them into the 27256.

You could also do some bit shuffling and extract the BASIC from the 5160 ROMs, but it's a little more involved. If you would like, I can also prepare and test a BASIC ROM (I have your motherboard also).
 
Thanks Chuck. I did it. With concatenated file that is identical to yours. Now the BASIC is detected by Anonymous BIOS but when I press space it is not running. Computer freezes. I only have 150ns 27256 EPROM now. May it be I need faster ones at 4.77Mhz ? I tested it also with Award and Phoenix BIOSes, FDC and XT-IDE cards pulled out, and these BIOSes simply say Boot Disk Failure, no BASIC started. I did not test it with ERSO BIOS, cause something happend to the EPROM apparently, it only beeped and I have no mood anymore :-( Nice try, I learned again something.
 
archeocomp said:
Thanks Chuck. I did it. With concatenated file that is identical to yours. Now the BASIC is detected by Anonymous BIOS but when I press space it is not running. Computer freezes. I only have 150ns 27256 EPROM now. May it be I need faster ones at 4.77Mhz ? I tested it also with Award and Phoenix BIOSes, FDC and XT-IDE cards pulled out, and these BIOSes simply say Boot Disk Failure, no BASIC started. I did not test it with ERSO BIOS, cause something happend to the EPROM apparently, it only beeped and I have no mood anymore :-( Nice try, I learned again something.
Click to expand...

I've tested it on PCE IBM 5150 emulator with 32KB BASIC. (CPU mode : 4.77MHz)
It is DTK/ERSO BIOS 2.42.
Total ROM amount is 40KB
IBM BASIC C1.00 launches well on emulator.

Can you attach your BIOS?

P.S. By the way, CGA Font for DTK/ERSO BIOS must be dumped.
It seems to be different from original CGA font when I see Character font on SCREEN 1.
 
archeocomp said:
Thanks Chuck. I did it. With concatenated file that is identical to yours. Now the BASIC is detected by Anonymous BIOS but when I press space it is not running. Computer freezes. I only have 150ns 27256 EPROM now. May it be I need faster ones at 4.77Mhz ? I tested it also with Award and Phoenix BIOSes, FDC and XT-IDE cards pulled out, and these BIOSes simply say Boot Disk Failure, no BASIC started. I did not test it with ERSO BIOS, cause something happend to the EPROM apparently, it only beeped and I have no mood anymore :-( Nice try, I learned again something.
Click to expand...

Try (just for yucks) replacing the ERSO BIOS with a genuine 5160 BIOS.
 
Try a 5150 BIOS, which should be easy enough to find.

Have you booted up the machine and used debug to see what's actually at F600:0000? I don't recall that the manual explicitly calls this out, but I could be mistaken.
 
archeocomp said:
I could not find an 8k image. Maybe you can point me ?
Click to expand...
The breakdown of the 11/08/82 revision of the 5160 BIOS is [here].
From that, you can see that you need the final 8 KB of chip U18 of the 11/08/82 revision.
Obviously, the 8 KB needs to sit at FE000.
Images of the 11/08/82 BIOS revision can be found [here].
 
modem7: thanks. I did not look properly enough before at the memory maps. I programmed last 8kB of U18 into 2764 EPROM and it works.

BASIC mystery is solved as well. As Chuck suggested I looked at the contents of ROM from running PC. I discovered that the address lines for 27256 socket must be screwed somehow. BASIC was there but it it began with 56 69 6A 6C which is contents of fourth BASIC file. The virtual four 8kB banks were in this order Bank3, Bank0, Bank1 and Bank2. I concatenated the BASIC files this way: BASICC11.F8+BASICC11.FA+BASICC11.FC+BASICC11.F6. Now it works :)

I attached picture of the type of my board (picture found on the internet) if someone finds it interesting.
mazovia-super_turbo III.jpg
 
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