Unknown card on Osborne 1

giobbi said:

...I'm wondering if a copy of the rombo disk is stored into the eproms, and if there's a way to extract it and to make a bootable floppy from it?...

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It would have been smart for the previous owner to have saved those files, but I don't see them on the RomDisk.

CP/M with Rombo BIOS?
The last 3 clusters in the Rombo have a version of CP/M installed. It may the the copy of CP/M that has been modified to support the Rombo. Its loaded starting at address 7D00 of Eprom8.

I'll try to confirm Rombo stuff in its BIOS and BDOS tables, then figure out how the Rombo forces the Z80 to boot from it?

JDallas said:

The last 3 clusters in the RomDisk have a version of CP/M installed (or so it appears. It may the the copy of CP/M that has been modified to support the RomDisk. Its loaded starting at address 7D00 of Eprom8.

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This is a good new, I believe, expecially if it is a fully image of the original disk.

JDallas said:

The key is, how does the Rombo force the Z80 to boot from it?

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I don't believe it can boot from ROM disk. But, since the ROM disk becomes the A: drive, it host a CP/M system copy so, when the computer look for some system file, it will be found into the A: drive as usual (the ROM disk, in this case).
Maybe we can use this system set to make a bootable floppy? Unfortunately I don't know much about how to do that...

JDallas said:

Can you describe what happens when you turn on the Osborne-1? If you get an A:> prompt have you tried entering WS or WS.COM?

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After the boot phase from floppy drive A:, I get an A> prompt, but if I type WS or WS.COM it only returns an error (WS?).

giobbi said:

...I don't believe it can boot from ROM disk...

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There appears to be a version of CP/M in the Rombo Eproms. Its not attached to the directory which suggests its extracted in direct memory transfer into Z80 memory.

It may be that a Rombo CP/M cold boot disk was in the floppy. The articles you referenced also stated that you could boot up and be in Wordstar in 11 seconds.

I'll write a file ripping program in a few days to assemble each file from the various Eproms per the Rombo directory. You could then take those binary files and port them to a Osborne floppy by some process.

forget the e-mail, get the images here:

www.verrua.org/osborne/rombo1.jpg
www.verrua.org/osborne/rombo2.jpg

I have to run now, but I will read your latest post later, with some more time...

-- Giovi

EDIT ----
Reading better the pages at the site you passed me, I discovered that little switch is for Read Only / Read-Write Eproms. In fact you can program the eprom directly from the Osborne 1 + Rombo card and its dedicated software. They sold an eprom eraser for extra 35$ too. So the switch shouldn't make difference if you are just reading the eprom content.

JDallas said:

There appears to be a version of CP/M in the Rombo Eproms. Its not attached to the directory which suggests its extracted in direct memory transfer into Z80 memory.

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From one of the articles you quoted:

The first thing you do after installing the circuitry is to create a boot-up disk with a special 58K version of CP/M and with installation programs and so on on it. You put this disk in Drive A as usual and boot up on it. You now have three "drives" available [...] and the option of having warm boots to the ROM or not.".

hmmm, create a floppy, but how?
About warm boots to the rom: if you can warm boot, it maybe means the full cp/m modified version is on the eprom and we (I mean: you! ^_^ ) only need to discover how to pass it on a bootable floppy (DD please, my ibm xt doesn't write SD floppies! )

--Giovi

giobbi said:

...create a boot-up disk with a special 58K version of CP/M...

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The CP/M hidden in the Rombo is three clusters long, or 6KBytes. 64KB - 6KB - 58KB.

That makes me think it is the Rombo version of the Osborne system. The floppy that came with the Rombo creates that, but once you have it, the floppy might be moot (unless its required to load more files).

wow, it seems to be quite a huge amount of work with Corel Draw!
Let me see if I can help you in some way with your reverse engineering...

I'm wondering too if it's possible to take an .IMD or ID0 disk image and simply replace the modified hex parts (admitting the system files size is the same) in order to have a bootable image to "burn" onto a floppy...

Rombo Community - First Contact

Rombo Community - First Contact

I checked one of my other vintage computer sources and some search hits about Rombo.
Unfortunately they were all about Eprom products for Sinclairs and other UK computers.


In reviewing some of the search engine hits I discovered:
(1) "Rombo Productions" is mentioned as making similar boards or external boxes for other computers, specifically the Spectrum. Descriptions are similar with the 8 Eproms being the tie; just different interfaces for other systems
(2) A little information on some of Rombo Productions products:
http://compgroups.net/comp.sys.sinclair/strange-rom-box/1226410

About 31 search hits and most were just vectors to the same set of messages. (2) above was the only useful thread. It appears that Rombo made RAM axpansions and Video Digitizers too.


Internet Searches for Rombo Productions:
The messages I read suggested Rombo focus on computers in the UK so it became no surprise that the company was there. The previous comapny in California may have been an US distributor or perhaps bought the rights to that design.
(1) Rombo Productions still exists at the following address; listed as dealer in computers:
. . ROMBO PRODUCTIONS LTD.
. . 2 Murieston Grove, Livingston. West Lothian. EH54 9AY
. . Service provided by Hawley Associates (UK) Ltd.Customer service 0330 122 4063.
. . Company Description
. . Incorporated as dealers in computers.
(2) A useful URL showing their video digitizer products for Ataris but lists the names of the three key employees. Might search for some of these:
. . Hardware: Colin Faulkner
. . Software: Marcus Sharp
. . Software: Richard Siddons
. . UPDATE: Found Hardware guy Colin Faulkner
. . . . http://www.companydirectorcheck.com/colin-raymond-faulkner
. . . . http://www.companydirectorcheck.com/colin-raymond-faulkner-2
. . . . That shows his work record through 2011.
. . . . Born in 1954 odds are he's still around.
. . . . Find him and he might be able to help you with Rombo documentation or software.
. . . . Check UK based computer clubs and scan to see if he's posted message in comp.sys areas
(3) A link to one of their other products, a Rom board for another type of computer. I looked at the PDF manual and nothing is applicable to the Osborne version.
. . http://www.cpcwiki.eu/index.php/Rombo_Rombox
(4) Worswick Industries still exists. No Rombo information though:
. . OddCables.com is sponsored by Worswick Industries (A Division of RF Industries)
. . We stock hundreds cables...

I received an interesting e-mail from John Crane I wish to quote here. John is an Osborne owner who's giving some ideas about the Rombo board, based on his past experiences:


"A very nice addition for the Osborne. I have the Drive C and the Trantor hard drive for the Osborne, but I think this would be even faster! Incredible.

About getting it running. It's not necessary to have a floppy with a modified CPM. You only need to run a specific program that then implements the patches in CPM when it runs. That way, you don't need to have modified CPM disks; the little routine does it for you when you need it.

Also, I don't think you will find that code in the EPROMS. Because you need a program to access the EPROMS. The code to do that doesn't require a change to CPM (whereas the ramdisk does). This code simply copies data from EPROM to RAM, likely using I/O ports to access different higher order bits necessary to get to the EPROMs data, but nonstandard on a Z80. I know, I did something similar on an IMSAI 8080 a few years ago - I designed an S-100 card with a 512K flash ram chip accessed from some 8080 assembler code I wrote. A very similar scheme."

--Giovi

I will try to find a minute in the evening to extract the card and take better pictures of it.

Giovi

Rombo CP/M file in high memory:
For some reason the CP/M file in the high Eprom memory space was written differently than the other directory clusters. Its already clear that the CP/M flie block is not attached to the CP/M directory in the Eproms.

Unlike everything else stored therein, the CP/M file is written in 128 byte blocks across the 8 Eproms instead of 256 byte blocks elsewhere. This suggests it is accessed by a different program - maybe its a boot loader?.

I generated the hex-text dump for 128 byte blocks and it aligned properly. This CP/M file is a mystery still. I've mapped the range of its jump destinations so I just need to match that up with the right function.

I've read it. But I think you maybe would leave it, other people can get ispired by you technique in case they'll need to follow the same path for other cards.
Your way to proceed is quite interesting, I think.

Watching a clip on youtube, I just discovered my Osborne has a strange behavior: it took about 80 secs. to pass from the boot screen ("press ENTER... drive A:...") to the next splash screen, with the big "O" logo.

I'm not sure if it has to do with the rombo board or it's a compatibility issue, due to the fact I did the cp/m boot floppies using my IBM XT and the .IMD / .ID0 disk images I downloaded from the web.

wow!!!

Are you doing that because you want to build a rombo board by yourself, or is it just a kind of reverse engineering needed to understand how to make the board to work?
And are you sure in the end you will be able to make the piece of software needed to call the board?

My question could seem (and could be!) silly, but please keep in mind I understand almost nothing about hardware and low-level programming.

However, good work, indeed! I can't wait to see the final result!

cheers,
Giovi

I'm curious to see how the Rombo was designed and how they tied it to the operating system; not that I expect that to be useful information, its just a puzzle I'm working on.

HARDWARE: I don't need 100% of the schematic captured to realize how it works. Usually there is a point when enough of the circuit capture is done where all secrets disappear in so far as the schematic... i.e. you could document the way the design works without bothering to get all the pin numbers actually used.

SOFTWARE: I don't believe that would be a good use of time writing new software to make the Rombo work because its likely that someone has the Rombo software package, so that should be pursued. However it might only take a simple driver/table modification to make the Rombo function in its RomDisk / RamDisk capacity. Time will tell, from the schematic capture.

JDallas said:

I'm curious to see how the Rombo was designed and how they tied it to the operating system; not that I expect that to be useful information, its just a puzzle I'm working on. I don't need 100% of the schematic captured to realize how it works.

I don't believe that would be a good use of time writing new software to make the Rombo work because its likely that someone has the Rombo software package, so that should be pursued.

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I really wish to find somebody with the rombo software, I'm curious to see it works. Actually it's quite a waste of vintage, working but useless hardware, due to lack of proper software :-(

Since I didn't find any further reference to this card, I believe it have been sold a few copies of it (in 1986 most people already passed to PC clone or Amiga or Apple), so will be hard to find somebody who still own it and its (working) floppies in present day...

I already removed the rombo card from the Osborne to see if in some way it was intefering during the boot phase, causing the boot delay (it wasn't), so it will be absolutely easy for me to do every check you need. But, since I had to remove the soldered Z80 from the card, I can't put it into the Osborne again easily (unfortunately I can't simply solder a socket, because there's no space left for the socket + Z80: too thick to fit under the CRT assy).

My multimeter isn't a tech marvel, but it works enough to check continuity between two pins. No problem for that. I also have a logic probe and an usb scope, but since I removed the card...

My time zone is UTC -3 hr (Brasilia time). But we have to consider the summer time, here.

IRC channel... mhh, could it be the usual Facebook?

The weekend could be not a good moment, but for me it's ok almost every night of the week, Monday to Thursday.

If you want to simply pass me a list with the pin-to-pin check I can check it "off-line".

I see no problem, but you must to pass me a picture with the IC numbers... I mean: I suppose you numbered every IC, since there's nothing written on the board.

I spent a lot of time testing continuity when I fixed my Commodore 3032 (I think I checked every single trace on the board!) so nothing scares me now! ^_^

Just pass me the ICs number scheme and the traces you want to check.

--Giovi

ok, I will wait for your PM.

A question: do you think there's a way to make my rombo card to work?

...do you think there's a way to make my rombo card to work?...

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Yes.

The circuit will reveal what needs to be done in a firmware driver so that you can access the Eprom files.

I'll probably create a simple bit of code you can enter via DDT to do some test reads.

I can write some code for ASM that you can paste and compile into that.