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Hi guys.. Happy New Year!

A while back I scored two OSI Challenger chassis with 8 slot backplanes and PSUs.. one was a Challenger II and the other was a Challenger 8.

I have a few questions I've been having trouble getting answers for.

1) What would be the stock configuration for each machine (ie. Which boards would typically be in them when they were first offered). I'm thinking the C2 would be a 500 and a 540a video card plus ram? I'm less sure of the C8.. I've seen them with various CPU boards.. often the triple cpu one.

2) For my C2 chassis, the case lid is painted brown like the c8.. did C2s sometimes come like this? I've most often seen them with a black lid but today I saw a C2 on ebay that.. well its hard to say for sure but the lid looks kind of brown. Just want to have correct color if there was one.

For the C2 I already have a 500 cpu board and 540a video card so I'm hoping I got that right. Have also been offered a 505b board for the c8. My only trouble with the 500 board is I know for sure one of the basic roms is dead. Not sure if you can run an eprom together with the original roms to replace it?

Many thanks!

Hi,

I received a C2 cassette based system from an OSI dealer with a 500 CPU, 540A video, 542 keyboard and a 420C 4K memory card. The 540A was initially configured with a 2513 character generator and 6bit RAM. Eventually this was upgraded with an OSI chargen and 8bit RAM (much better!). This was initially delivered in a C2-4P blue & black case, but was switched out for a C2-8P (silent) blue & black case a couple weeks later. I've only see original C2 systems in blue & black cases, including floppy drives.

The C8P I found years later came with a 502 CPU, 540B video, 542C keyboard, additional 527 RAM, and an A15 I/O board in the back panel. It's a tan case with brown cover. I think a 505 CPU would be acceptable in C8 for disk based systems, especially since it has the A15 board. (I have no idea what this C8 shipped with. I'd expect customers could get many configurations depending on needs.)
I don't recall seeing a mixed color scheme case from OSI in person or in their ads, but since the parts were interchangeable its not surprising to see them mixed.

You didn't say which BASIC ROM was bad, but it wasn't uncommon to replace BASIC 3 with an EPROM to correct the BASIC string garbage collection bug. The BASIC ROM sockets on the 500 CPU can be configured for a variety of chips. See Manual. The 2316 ROMs uses active high enable, but a 2716 uses active low. The OSI500 generates both, you have to cut a trace & jumper to switch. I don't recall if its easier to pop a pin out of the socket & jumper the eprom or change the socket connection to fix the other enable pin. In the end it may be easiest to replace all BASIC ROMS with EPROMS & follow the cut/jumper instructions in the manual.

Hope this helps,
-Mark

Thanks Mark.

Yeah I had a feeling black was the proper color - I guess the lid on my C2 case was borrowed from somewhere else.

I haven't seen too many 502 boards unfortunately... mostly 505s. I may have to go for whatever i have to to get it going. I don't imagine it makes much functional difference. The only thing that sucks is neither of them have their original keyboards. I believe the C2 would have had the first version OSI keyboard with the beige keys? I have that on my C2-4P. I do have a later version OSI keyboard so I'll have to make do with that for now. Unfortunately OSI keyboards, when they're sold loose, are subject to the depredations of mechanical keyboard collectors. One for a C8 went recently for $400.

I believe it is the BASIC 3 ROM that went bad. But totally bad - the system would not function correctly at all until I swapped it out.