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Leading Edge Model M BIOS

H

hupshall

Member
Joined
Dec 31, 2018
Messages
28
Location
Redmond, WA
I'm fixing up my families old Leading Edge Model M. I've had to clean up some battery leakage as well as replace a few chips, but the system is now booting just fine.
The issue that I have come across is that I can't seem to get the computer to boot with any EGA or VGA cards. The selection of cards that I am currently using are:

Paradise EGA Basic and the Orchid Designer 800. Both of these cards test fine in another computer that I have. I have a feeling that the BIOS that is in the computer ( (c) 1984 ) just doesn't support BIOS extensions.

I have come across several mentions of needing to have version 4.71 of the Bios for MS-DOS 5.0, as well as being mentioned in another VGA installation manual.

Questions:
Does anybody know where I could perhaps find this version of the BIOS? Or do you think the Turbo XT BIOS project would help?

Thanks in advance.

-Huw
 
As I recall I was not able to use any 3rd party cards in my M either. Therefore the questionable Mobo I have won't be of any help I presume. But if you're interested in general parts, I have everything except the floppy drive. The Sperry equivalent was the HT XT or something like that. Search the archives, there have been mentions of the Sperry not long ago.
 
Leading Edge Modem "M". Yep, I've got one, and I have upgraded the BIOS for EGA Support, as the Original BIOS didn't work with EGA.
The ONLY Problem is I don't have that BIOS Chip with me, or I don't think I do. I'll have to Search my Hard Drive. I'm away from the
Model M or I could pull the EPROM and Burn another copy. That was Years ago..............Mid 80's to early 90's. If I remember correctly
that upgrade was a bit expensive at the time.

Let me do a bit of searching. I burned the Replacement EPROM's at work. Maybe I have it on my old Partition. Otherwise it will be
April 2019 before I can work on it.

Thanks.

Larry
 
hupshall,
You better run out and buy us two lottery tickets tonight. You just hit the LUCKY NUMBER............
Code: 
./386_C/CDR/M471.ROM -- BINGO

Send me PM with your email address. I'm sure the Code is in HEX bytes, as my BP Microsystems EP1 used a serial
port at 9600 and Hex bytes to program with. If you need it converted to Intel or Motorola, I'm sure Linux can convert
it to what you need. I'll email it and you can burn it. I forget what manufacture type EPROM the Model M had, but you
want to make sure the speed rating of the one you use is at least as fast, or faster than the original.

I forget what EGA card I used but it worked Perfect. I converted 3 Machines back in the day.


Thanks.

Larry
 
I'd be interested to know if the BIOS chip has a version # on it.

My M is working fine with an XT-IDE - I have it booting and running with DOS 4.01 - I'm still digging through boxes trying to find my old MS-DOS 5.0 360k floppies
I also have a really old school IBM Color Graphics CGA card in it so I have a display - But the long term goal would be 16 colors.
 
hupshall,
It looks like it's a 1K EPROM. I don't remember if it was 24 or 28 Pin. You probably already know that.

Code: 
00000000   42 30 34 46  30 34 30 30  30 30 30 30  30 30 30 30  B04F040000000000
00000010   30 30 30 30  30 30 30 30  30 30 30 30  30 30 30 30  0000000000000000
00000020   0D 0A 45 39  39 35 30 30  45 39 43 33  30 31 46 46  ..E99500E9C301FF
00000030   46 46 46 46  46 46 46 46  46 46 46 46  46 46 46 46  FFFFFFFFFFFFFFFF

File Size is:
34818 Jan 1 20:08 M471.ROM

34818 / 32 = 1088

1088 * 2 = 2176

64 blocks of 32 bits plus 0x0D 0x0A (128 of these) - 2048 + 128 = 2176

1K EPROM

What format do you need it in? Right now, it's in HEX BYTES. Two bytes make up a HEX byte. 42 = B and 30 = 0
So, the first byte in the EPROM is 0xB0.

I am pretty sure I can change it to Intel, Motorola, or the format you need.

I have no other information for it right now.

Thanks.

Larry
 
SoneGuy,
Sure, that is a good idea. But, no where on that site does he have a address for contact posted. How does one find his email address.
I know I've emailed him before with other BIOS ROM's I had saved, but I forget his name.


Larry
 
SomeGuy said:
I'd suggest sending a copy of that ROM to Modem7, for addition to his PC BIOS ROM page: http://www.minuszerodegrees.net/rom/rom.htm
Click to expand...
ldkraemer said:
Sure, that is a good idea. But, no where on that site does he have a address for contact posted.
Click to expand...
I have no contact details there in order to stop a never-ending barrage of IBM 51xx questions (and advice on how to make my site better).
I want people with questions to come here instead, hence my "For queries or assistance, I suggest ..." text on the root page.

ldkraemer said:
How does one find his email address.
Click to expand...
Via the PM that I see that you subsequently sent.
 
Ray,
THANKS. I sent you an email.

hupshall,
Will you read the Original BIOS ROM/EPROM to a File so we also have it? I'll also forward that to Ray for his collection.

Thanks.

Larry
 
@hupshall, saw your post earlier but, only had time to respond now.
I have the "Sperry HT" (which is actually another brand name for the Leading Edge Model M - the "M" standing for Mitsubishi). The Model D used Daewoo parts.
I've attached the v4.71 BIOS from my Sperry XT.
View attachment Sperry HT - 4.71 Bios.zip
 
I just compared the Sperry ROM with my M471.ROM (after changing it to Binary), and they are the same.

If I remember correctly the M471 Ver 4.71 was EGA ONLY, as VGA wasn't out at that time. Although hupshall
states it works with VGA, but gives a beep code on boot up.

M330.ROM has been forwarded to Modem7.

Larry
 
Well, according to the Video 7 VGA 1024i card manual http://minuszerodegrees.net/manuals/Video 7 VGA 1024i.pdf

"Leading Edge Model M: Must have Sperry ROM BIOS
4.71 or later ."

"Sperry PC : Must have Sperry ROM BIOS 4.71 or later."

As well as quite a bit more detailed compatiblity information for other systems.

So I'd at least expect a Video 7 VGA 1024i to work, although other VGA cards may be hit or miss.
 
Both the 3.30 and 4.71 revisions are now hosted in the collection at [here].
I also added a line for the Sperry HT, which directs the reader to the Leading Edge Model M.
 
THANKS RAY.

One thing did cross my mind last night, and that was possible switch setting on the Motherboard that might need to be changed.
I searched my old Emails back to the 1990's but didn't find any information about the BIOS Upgrade. It must have been
a prior provider I used, and I don't have those emails because of four virus attacks.

Would anyone have any information on the Motherboard switch settings for the Model "M". I won't be able to access my old computer
until spring.

Thanks.

Larry
 
ldkraemer said:
One thing did cross my mind last night, and that was possible switch setting on the Motherboard that might need to be changed ...
Click to expand...
If the designer was very closely following the IBM 5150 design, then what you write of may be in relation to switch block SW2 on the motherboard.

Refer to the diagram at [here]. In the early 5150 machines, switches 5/6/7/8 on SW2 were normally off. Consequently, in most cases, an upgrade of the BIOS to the final revision required turning switch 5 on.
 
Ray,
I sent jesolo a PM asking for any information he had on the Sperry HT. I got this replay:
Yes, SW1, dip switch 5 & 6, both have to set to "ON" (which is the same setting for "NONE").
Refer this link (right at the bottom): http://arvutimuuseum.ee/th99/m/I-L/30486.htm
Just take note they incorrectly refer to this as the DRAM Switch configuration and it's SW1/5 & SW1/6, NOT SW2/5 & SW2/6.
Click to expand...

hupshall, is going to try these updated settings.

I've attached the XT information that I found for additional reference.

THANKS.

Larry

XT-Switch.jpg
 
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