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Pet Rescue
October 10th, 2014, 12:53 PM
Just noticed this B series auction on Ebay, on the box it says B715.

http://www.ebay.co.uk/itm/Commodore-B700-Personal-Computer-1982-vintage-/171493816386?pt=UK_VintageComputing_RL&hash=item27edd3f842

Was there such a model, I know there was a B710 and B720.

Eudimorphodon
October 10th, 2014, 02:10 PM
Commodore was never even remotely consistant about what they'd name things, but... that's a weird one.

I'm sure this is a stupid question, but was it possible to fill three RAM banks on a B-series motherboard and make a unit with 192k or did you have to add banks in pairs? Could a "715" be a 192k unit?

Pet Rescue
October 10th, 2014, 03:06 PM
That sounds quite a reasonable answer, as you say Commodore were a bit inconsistant regarding model labelling.

sjgray
October 17th, 2014, 09:25 AM
Yes, model numbers/names were a mess. It's hard to say exactly what that machine is. I have emailed the seller to find out more.

Yes, you can fill 3 banks of ram for 192K. That configuration was planned but never realized. The source code to the kernel has an option for 192K and that determines which banks BASIC variables will use. Commodore only released 128K and 256K BASIC versions, and most commercial software required the 128K roms.

If you have BASIC128 roms and you add another 64K or 128K that memory is seen but not allocated. If you have the BASIC256 roms then the machine must have 256K ram.

Steve

Pet Rescue
October 20th, 2014, 11:22 AM
Steve would there be any compatabilty issues due to differing memory sizes with regards to software, would 128k software work ok on 192k and 256k models?

Still trying to understand these machines what with different CPU and memory banking!

snuci
October 20th, 2014, 11:26 AM
Hi Steve,

Did you buy it? If so, how much is shipping on something like that?

billdeg
October 20th, 2014, 11:48 AM
My opinions here.....The "715" is kind of arbitrary. There is a difference between US and European naming. I can say that this 715 is not the same thing as the later European B700 (US CBM 128-80 hi-profile)

I have a very similar unit to this one, what I call a "B700" because there is no label or anything on it, the hi-profile analog of the B500 (before the B128-80). It looks like they made a few production versions in the West German plant, the S/N is 75. I *assume* the power leads are European? There are others of these, huh? My "B700" is American but it looks identical to the computer in the Ebay auction (see pic below), mine has US power leads. The European "bar 7" makes me *think* it's a West German product and not an American. Also the German on the box...

A while back I wrote this up:
http://vintagecomputer.net/cbm_b_prototypes.cfm

http://vintagecomputer.net/commodore/bx700/B700_c.JPG
For fun I put a CBM 8088 co-processor in mine, making it a theoretical "BX700"

With the 8088 card I was able to load MS DOS 1.25 on the 700
http://vintagecomputer.net/commodore/8088_co-processor/MS-DOS_125b.jpg

In my opinion this is very very rare and a great buy for the money paid. I got mine from Bruce Fierson before he died. He was the 2nd president of the CBUG before it disbanded, and he said it was his favorite.
b

sjgray
October 20th, 2014, 12:16 PM
Steve would there be any compatabilty issues due to differing memory sizes with regards to software, would 128k software work ok on 192k and 256k models?

Still trying to understand these machines what with different CPU and memory banking!

In BASIC, the BASIC ROM determines how variables are allocated. BASIC programs always reside in BANK1. Bank 2,3,4 are used for variables. So with 128K all variables are in bank 2. If you have 256K then simple strings and arrays are put in banks 3 and 4. If you are programming in ML then you can use any bank as you like. Most small ML programs try to place themselves in the small 1K free ram in BANK15 so they have easy access to the KERNAL routines, the IO and the screen. Larger programs would have to go either in the 24K cartridge space in BANK15, or in another bank. If in another bank they would have to set up some complicated transfer code to call KERNAL routines. These routines must be synchronized so that, when the BANK is switched, execution can continue at the same address in the new BANK. There is a great article by Jim Butterfield in the documentation section of my CBM-II webpage.

Most commercial software was written for 128K machines since that seemed to be the most common platform. 256K machines could install 128K roms for better compatibility, or even install a hardware board to allow switching between different roms (see hardware addon section).

In a stock machine, when running BASIC all code executes from BANK15. The BASIC interpreter fetches data from the other banks using the CPU Indirection Register at $01, which is visible in all banks. Two instructions; LDA ($zeropage),Y and STA ($zeropage),Y are modified to fetch/store from the bank set in the $01 register. Execution is still in bank 15. When using BASIC 4+ (actually it's basic 4.76) the BANK command sets the bank you want to access when using PEEK/POKE. The FRE(bank#) command can tell you how much memory is available in each bank.

One of the coolest pieces of software for the B-series is the 8432 PET Emulator. For each bank of RAM you can load a virtual CBM8032 machine. Only one runs at a time, but you can switch between them at will.

Steve

sjgray
October 20th, 2014, 12:18 PM
Hi Steve,

Did you buy it? If so, how much is shipping on something like that?

Yes, I won the auction! So, I'll be sure to document the machine on my web page. Shipping was quoted as 150 euro to Canada. ouch! Still, I'm glad I could add it to my collection.

Steve

sjgray
October 20th, 2014, 12:24 PM
My opinions here.....The "715" is kind of arbitrary. There is a difference between US and European naming. I can say that this 715 is not the same thing as the later European B700 (US CBM 128-80 hi-profile)

I have a very similar unit to this one, what I call a "B700" because there is no label or anything on it, the hi-profile analog of the B500 (before the B128-80). It looks like they made a few production versions in the West German plant, the S/N is 75. I *assume* the power leads are European? There are others of these, huh? My "B700" is American but it looks identical to the computer in the Ebay auction (see pic below), mine has US power leads. The European "bar 7" makes me *think* it's a West German product and not an American. Also the German on the box...

A while back I wrote this up:
http://vintagecomputer.net/cbm_b_prototypes.cfm

http://vintagecomputer.net/commodore/bx700/B700_c.JPG
For fun I put a CBM 8088 co-processor in mine, making it a theoretical "BX700"

With the 8088 card I was able to load MS DOS 1.25 on the 700
http://vintagecomputer.net/commodore/8088_co-processor/MS-DOS_125b.jpg

In my opinion this is very very rare and a great buy for the money paid. I got mine from Bruce Fierson before he died. He was the 2nd president of the CBUG before it disbanded, and he said it was his favorite.
b

Very nice! I have B500's and P500's and was only missing the B700. I'm hoping this machine is really a 715 with 192K ram, but I'd still be happy with 128K or 256K! ;-)
I have to decide whether to keep the machine intact or replace/convert the power supply to 110V. The machine looks really nice and I'd like to be able to play with it. I also have a couple 8088 boards that I still need to get working. Sadly, I haven't had much time for them, but hopefully I will when the machine arrives. One of my "projects" is to build a BX256-80 with the 8088 board AND internal disk drives. To me this would be the ultimate CBM-II machine. I have all the parts, and hopefully I can get everything working!

Steve

billdeg
October 20th, 2014, 01:11 PM
One thing I learned about the 8088 boards...once you got the right software load process the boards work perfectly every time. There was a time when it seemed like none of the boards worked, per chatter on cbm-hackers, etc.

I'd like to learn more about building the internal drives part. I guess you pop out the black plate (never checked to see if they do pop out) ... I have a 8296 with internal drive, but it's not functional.

KC9UDX
October 20th, 2014, 02:56 PM
I'd like to learn more about building the internal drives part. I guess you pop out the black plate (never checked to see if they do pop out) ... I have a 8296 with internal drive, but it's not functional.

I've never heard anyone talk about doing this with a 2001N, but, mine clearly has floppy drive cutouts in the front panel, and threaded mounting holes. I know not all of them do. I wonder if it's ever been done.

21075

billdeg
October 20th, 2014, 03:39 PM
uh oh, hacky senses are tingling

KC9UDX
October 20th, 2014, 03:43 PM
uh oh, hacky senses are tingling

I thought about this the first time I noticed the cutouts (the first time I opened it). I was shocked to see them. I thought about what it would take to put two 5-1/4" floppies in there, and, either I do something completely not traditionally Commodore compatible, or, I have to cram the boards from a 2040 drive or something inside the PET. Not ideal. Maybe someday though. :D

I didn't mean to derail this thread. But, I wonder how many other cases are like mine. I never see them like this, all the others I've seen have a sticker over solid panel.

sjgray
October 20th, 2014, 04:32 PM
One thing I learned about the 8088 boards...once you got the right software load process the boards work perfectly every time. There was a time when it seemed like none of the boards worked, per chatter on cbm-hackers, etc.

I'd like to learn more about building the internal drives part. I guess you pop out the black plate (never checked to see if they do pop out) ... I have a 8296 with internal drive, but it's not functional.

Yes, the 8296D drives will work but there are a few issues. First, the analog board is mounted at the back where the CBM-II power supply is located. I found that if you remove the metal plate under the board, that the analog board will mount between the power supply and the top of the case. You will need to remove one post holding the power supply. And second you need to figure out how to connect the IEEE. There is no internal IEEE header on the CBM-II motherboard like there is on the 8296D board.

This is described on my BX700D project page, but I was hoping to add some pictures
http://www.6502.org/users/sjgray/projects/bx720d/index.html

My "BX720D" is 5 feet away waiting to be worked on...

Steve

sjgray
October 20th, 2014, 04:52 PM
I thought about this the first time I noticed the cutouts (the first time I opened it). I was shocked to see them. I thought about what it would take to put two 5-1/4" floppies in there, and, either I do something completely not traditionally Commodore compatible, or, I have to cram the boards from a 2040 drive or something inside the PET. Not ideal. Maybe someday though. :D

I didn't mean to derail this thread. But, I wonder how many other cases are like mine. I never see them like this, all the others I've seen have a sticker over solid panel.

Yes, the "HP" PET cases have removable bezel. Apparently, commodore were working on "DMA" drives (from an old article I read from Jim Brain), which would be controlled directly by the PET CPU, and so they designed the case to support them. Not much else is known about it, but I assume they never got them to work. They must have still wanted internal drives, proven by the fact that some early 80-column PET motherboards have an internal IEEE connector on the board. But again, I guess they never quite got it to work, or they decided that they made more money selling external drives.

Then yet again, when designing the CBM-II machines they actually planned for DMA drives. If you look in the user guide and the memory map you will see references to "low cost disk drives" and "disk port" (in the I/O space) and allocated dedicated RAM in bank 15. They still thought they could make DMA drives work otherwise they would have put an internal IEEE connector on the CBM-II motherboards, but they did not. If you read the Article about the Commodore 700 on my page in there you will find a reference about internal the "360K dual disk 750BX model" and that 32K ram was allocated in one of the banks.

It would not be until the C65 that commodore actually succeeded with DMA drives.

If you look on my "Pet Labels" page you will see a label from a machine with one internal drive:
http://www.6502.org/users/sjgray/computer/petlabels/index.html

Steve

KC9UDX
October 20th, 2014, 05:36 PM
If you look on my "Pet Labels" page you will see a label from a machine with one internal drive:
http://www.6502.org/users/sjgray/computer/petlabels/index.html
Very nice.

I wonder what the Rohde und Schwartz machine had inside.

sjgray
October 20th, 2014, 07:17 PM
Very nice.

I wonder what the Rohde und Schwartz machine had inside.

There were some third-party floppy interfaces for the PET that used standard disk controller chips. One that I know of was PEDISK (see sig) ;-) There were also PET-to-S100 bus adapters, and a few S100 controller boards that could be used.

Steve

Pet Rescue
October 21st, 2014, 05:15 AM
In a stock machine, when running BASIC all code executes from BANK15. The BASIC interpreter fetches data from the other banks using the CPU Indirection Register at $01, which is visible in all banks. Two instructions; LDA ($zeropage),Y and STA ($zeropage),Y are modified to fetch/store from the bank set in the $01 register. Execution is still in bank 15. When using BASIC 4+ (actually it's basic 4.76) the BANK command sets the bank you want to access when using PEEK/POKE. The FRE(bank#) command can tell you how much memory is available in each bank.

One of the coolest pieces of software for the B-series is the 8432 PET Emulator. For each bank of RAM you can load a virtual CBM8032 machine. Only one runs at a time, but you can switch between them at will.

Steve

Steve going slightly off topic, is this where the 6509 differs from the 6502. On the d0-d7 lines for opcodes would you use the extra logic to look for these instructions where the instructions for lda,y sta,y are called.(On the previous topic on the 6509 replacement) if that makes sense?

http://forum.6502.org/viewtopic.php?t=2023

P.S Congrats on winning the B715!

sjgray
October 21st, 2014, 06:04 AM
Steve going slightly off topic, is this where the 6509 differs from the 6502. On the d0-d7 lines for opcodes would you use the extra logic to look for these instructions where the instructions for lda,y sta,y are called.(On the previous topic on the 6509 replacement) if that makes sense?

http://forum.6502.org/viewtopic.php?t=2023

P.S Congrats on winning the B715!

Ok, so to recreate a 6509 you would first need to monitor writes to $00 and $01. $00 is the "execution register", so when you write to it, it will immediately set the bank where code is executed from. The $01 address is the "indirection register" which is used by the modified opcodes. The way I understand it, there is a line on the cpu that gets set when an opcode is being fetched. When that happens the data lines will tell you the opcode. If you see either of the two modified opcodes you would then need to change the memory bank for the subsequent read or write operation. When the read/write is complete you need to set it back to the bank from the execution register so that the next opcode can be fetched from the proper bank again. I think the main problem would be timing... knowing which exact cycle to change the bank lines.

Thanks! Looking forward to my 715!

Steve

Eudimorphodon
October 21st, 2014, 07:35 AM
One that I know of was PEDISK (see sig) ;-)

I just had to Google that up, and I'm sort of disappointed that the ROM included with it isn't a self-contained BASIC extension, only enough to bootstrap a DOS into RAM. I was suddently fantasizing that the ROM for that might be a good starting point for a project to wedge, say, a CompactFlash drive into a ROM socket a similar way. (I.E., use DOS wedge parts of the ROM and just patch the I/O routines. Unfortunately it looks like all the good parts were loaded from disk.)

sjgray
October 21st, 2014, 10:46 AM
I just had to Google that up, and I'm sort of disappointed that the ROM included with it isn't a self-contained BASIC extension, only enough to bootstrap a DOS into RAM. I was suddently fantasizing that the ROM for that might be a good starting point for a project to wedge, say, a CompactFlash drive into a ROM socket a similar way. (I.E., use DOS wedge parts of the ROM and just patch the I/O routines. Unfortunately it looks like all the good parts were loaded from disk.)

Yes, Mike N and I are hoping to find the PEDISK II software and clone the card. I've been wanting to re-create the CBM-II "low cost disk" option which I'm pretty sure involved a common floppy disk controller (likely a Western Digital). I have done some research into various disk solutions for different platforms and I think it's do-able. One of the most interesting ones I came across was the TIB-001 drive for the C64. It's a 3.5" drive connected via a C64 cartridge, which contains a FDC chip and a single EPROM. I have bought the same FDC chip and I have a dump of the rom. I was hoping to adapt that.

Steve

MikeS
October 23rd, 2014, 09:34 AM
Very nice.

I wonder what the Rohde und Schwartz machine had inside.That's Rohde & Schwarz, not Schwartz (or Rhode, Steve ;-) )

Can't say I've ever seen a 2001 with plastic case with drive cutouts, but 40/8032s like that were fairly common; here's what one would look like with 3.5" drives:

21124

Since 3.5" drives are almost identical to 8" drives, it'd really be nice to get that PEdisk working...

sjgray
October 23rd, 2014, 09:48 AM
That's Rohde & Schwarz, not Schwartz (or Rhode, Steve ;-) )

I don't know what you're talking about... ;-)

Steve

MikeS
October 23rd, 2014, 10:22 AM
I don't know what you're talking about... ;-)

SteveFellow dyslexics, untie!!!

sjgray
October 23rd, 2014, 10:34 AM
Fellow dyslexics, untie!!!

I'm so glad people like you are around :) Now I dare you to find the other typo on my other pages. Don't worry I'll wait...

Steve

MikeS
October 23rd, 2014, 02:10 PM
I'm so glad people like you are around :) Now I dare you to find the other typo on my other pages. Don't worry I'll wait...

SteveAlways happy to make the world a better place by correcting other peoples' spelling and grammar; surprisingly for some reason not everyone is as appreciative as you are...

The other typo (singular?) ... Umm... expect a PM...

;-)

Pet Rescue
October 23rd, 2014, 02:50 PM
Since 3.5" drives are almost identical to 8" drives, it'd really be nice to get that PEdisk working...

Mike what's a PEdisk?

:D Just yanking your chain!

KC9UDX
October 23rd, 2014, 02:56 PM
That's Rohde & Schwarz, not Schwartz (or Rhode, Steve ;-) )I had a very hard time convincing my browser plus phone to spell Rohde instead of Rhode. By Schwarz, I had given up.

MikeS
October 23rd, 2014, 04:24 PM
Mike what's a PEdisk?

:D Just yanking your chain!Yup, PEDISK, not to be confused with PETdisk:

http://mikenaberezny.com/hardware/pet-cbm/microtech-pedisk-ii/

Pet Rescue
October 24th, 2014, 02:34 AM
Yup, PEDISK, not to be confused with PETdisk:

http://mikenaberezny.com/hardware/pet-cbm/microtech-pedisk-ii/

Damn! I thought I'd got you with a typo Mike :o

Now I look foolish :stupid:

billdeg
October 24th, 2014, 03:58 AM
taking this thread off a cliff....the company CGRS is from my neck of the woods...long gone now. I have a CGRS 6502 front panel system that you can use to control things like the KIM / SYM-1 using a front panel. They must have had quite a place back in 1979-83

sjgray
November 4th, 2014, 06:30 PM
Ok, so my "B715" arrived today. There was no apparent damage in shipping. I requested that the seller wrap the original box to protect and preserve it, and he did.

Now, for the machine. On the back is a real label proclaiming the machine to be a "B700" as was stated in the auction. Opening it up I find an LP (low profile) motherboard with 256K factory installed ram, -03 firmware on eproms with adapters, and an "HP" character set rom.

So, anyone familiar with the CBM-II line (anyone?) will be asking... how did they fit an LP motherboard into an HP case? Well, the back right corner of the motherboard is hacked off and some traces "fixed". The whole motherboard is raised up (compared to a standard HP motherboard in an HP case). There is a cable that goes from the keyboard connector to a DB-25 on the front where the keyboard connector normally would be on the HP motherboards. There is a cable coming from the bottom of the motherboard with connector that connects to the normal monitor cable. The machine is 220V and seems to use a standard HP-type power supply.

At this point I have not plugged it in, but hope to do that soon. I also plan to take some nice pics and create a dedicated website for the machine.

So, I feel lucky to have acquired this machine for my collection and am pleased that it arrived intact. More info to come....

Steve

billdeg
November 4th, 2014, 06:55 PM
fantastic! A new puzzle to solve

sjgray
November 5th, 2014, 04:04 PM
Well, I powered it on, got something on the screen... fuzzy. looked like "undefined error" and a blinking cursor... then 30 seconds later.... poof. Looks like the power supply died. It took out a fuse on my step-up voltage converter too :(

So, hopefully nothing else was damaged. I wanted to replace the supply anyway.

Steve

Pet Rescue
November 6th, 2014, 03:51 AM
Well, I powered it on, got something on the screen... fuzzy. looked like "undefined error" and a blinking cursor... then 30 seconds later.... poof. Looks like the power supply died. It took out a fuse on my step-up voltage converter too :(

So, hopefully nothing else was damaged. I wanted to replace the supply anyway.

Steve

That's bad news Steve but it may be ok as my B256 did a similar thing. I powered it up and pop it went and took out the main fuse.
I feared the worst but the funk enstor filter had gone pop. I pinched one off a Pet wired it up, replaced the fuse and up came the boot screen :D

fachat
November 6th, 2014, 05:24 AM
Just short, You can easily reuse a PC power supply instead. I did this with my current repair project. I only needed a small 555-based circuit to create the 50Hz timer signal on the power supply connector on the board.
https://www.flickr.com/photos/afachat/sets/72157647798386959/

André

sjgray
November 6th, 2014, 08:20 AM
Ok, I now have a B715 webpage up. Check it out:
http://www.6502.org/users/sjgray/computer/b715/index.html

Steve

billdeg
November 6th, 2014, 08:31 AM
thanks for posting this info.

sjgray
November 6th, 2014, 08:47 AM
thanks for posting this info.

No problem. So I guess one question is... does your "B700" have an HP or LP motherboard?

Steve

sjgray
November 6th, 2014, 08:51 AM
That's bad news Steve but it may me ok as my B256 did a similar thing. I powered it up and pop it went and took out the main fuse.
I feared the worst but the funk enstor filter had gone pop. I pinched one off a Pet wired it up, replaced the fuse and up came the boot screen :D

That sounds promising. I hope that's all it is. I think I read that the filter is not really needed. I'll have to do some diagnostics.

Steve

Pet Rescue
November 6th, 2014, 10:01 AM
Ok, I now have a B715 webpage up. Check it out:
http://www.6502.org/users/sjgray/computer/b715/index.html

Steve

Steve have you got a picture of rear of the machine with serial number?

sjgray
November 6th, 2014, 10:11 AM
Steve have you got a picture of rear of the machine with serial number?

Yes. I also have the serial# sticker posted on my Main CBM-II page where I list the highest known serial#'s of each model.

Steve

billdeg
November 6th, 2014, 10:22 AM
No problem. So I guess one question is... does your "B700" have an HP or LP motherboard?

Steve

HP mobo. Nothing cut or rigged. The 8088 co-proc card covers the board part number, but it looks like any other HP 128 board.

billdeg
November 6th, 2014, 10:25 AM
Here is a link to a photo of the back of my "BX-700" for comparison purposes to yours. There is no s/n or label anywhere on the unit.
http://vintagecomputer.net/commodore/bx700/B700_b.JPG

http://vintagecomputer.net/commodore/bx700/thm_B700_b.JPG

I just fired it up, still works. I took some photos of the insides, to be posted when I get the chance.

b