8088 card replica

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8088 card replica

Michał Pleban
Hello!

As some of you are already aware, Ruud has started working on the 8088
card replica for CBM-II computers. With his permission, I put the
initial version of the card online:

https://github.com/MichalPleban/cbm2-8088-card

The card has been tested and works. As a bonus, I added my PC emulation
layer and PC-DOS 3.2 boot files in the card EPROM, so it can boot almost
instantly (after the 6509 code has been loaded from disk, that is).

Our next goal is to replace the 6565 chip with a 8255, so that the card
could be make with standard, easy to obtain parts.

Regards,
Michau.




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Re: 8088 card replica

Steve Gray
That's great! Would it be possible to add some pictures of the board itself, and with it installed?

Steve



From: Michał Pleban <[hidden email]>
To: [hidden email]
Sent: Sunday, March 25, 2018 9:53 AM
Subject: 8088 card replica

Hello!

As some of you are already aware, Ruud has started working on the 8088
card replica for CBM-II computers. With his permission, I put the
initial version of the card online:


The card has been tested and works. As a bonus, I added my PC emulation
layer and PC-DOS 3.2 boot files in the card EPROM, so it can boot almost
instantly (after the 6509 code has been loaded from disk, that is).

Our next goal is to replace the 6565 chip with a 8255, so that the card
could be make with standard, easy to obtain parts.

Regards,
Michau.






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Re: 8088 card replica

Michał Pleban
Hello!

Steve Gray wrote:

> That's great! Would it be possible to add some pictures of the board
> itself, and with it installed?

I don't see why not, I will take the photos next time I'll be
reprogramming the EPROM and post them online.

Regards,
Michau.


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Re: 8088 card replica

Rob Clarke
In reply to this post by Michał Pleban
Superb effort!


On 25/03/2018 15:52, Michał Pleban wrote:

> Hello!
>
> As some of you are already aware, Ruud has started working on the 8088
> card replica for CBM-II computers. With his permission, I put the
> initial version of the card online:
>
> https://github.com/MichalPleban/cbm2-8088-card
>
> The card has been tested and works. As a bonus, I added my PC emulation
> layer and PC-DOS 3.2 boot files in the card EPROM, so it can boot almost
> instantly (after the 6509 code has been loaded from disk, that is).
>
> Our next goal is to replace the 6565 chip with a 8255, so that the card
> could be make with standard, easy to obtain parts.
>
> Regards,
> Michau.
>
>
>
>


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Re: 8088 card replica

Clockmeister
In reply to this post by Michał Pleban

That's really cool guys!

On 25/03/2018 9:52 PM, Michał Pleban wrote:

> Hello!
>
> As some of you are already aware, Ruud has started working on the 8088
> card replica for CBM-II computers. With his permission, I put the
> initial version of the card online:
>
> https://github.com/MichalPleban/cbm2-8088-card
>
> The card has been tested and works. As a bonus, I added my PC emulation
> layer and PC-DOS 3.2 boot files in the card EPROM, so it can boot almost
> instantly (after the 6509 code has been loaded from disk, that is).
>
> Our next goal is to replace the 6565 chip with a 8255, so that the card
> could be make with standard, easy to obtain parts.
>
> Regards,
> Michau.
>
>
>
>
>


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Re: 8088 card replica

MiaM
In reply to this post by Michał Pleban
Den Sun, 25 Mar 2018 15:52:57 +0200 skrev Michał Pleban
<[hidden email]>:

> Hello!
>
> As some of you are already aware, Ruud has started working on the 8088
> card replica for CBM-II computers. With his permission, I put the
> initial version of the card online:
>
> https://github.com/MichalPleban/cbm2-8088-card
>
> The card has been tested and works. As a bonus, I added my PC
> emulation layer and PC-DOS 3.2 boot files in the card EPROM, so it
> can boot almost instantly (after the 6509 code has been loaded from
> disk, that is).

Excellent!
 
> Our next goal is to replace the 6565 chip with a 8255, so that the
> card could be make with standard, easy to obtain parts.

Btw the original schematics (CBM_8088_CPU_co-processor_schematic.pdf)
is hard to read. Just to make sure, is it indeed an 6525? All pin
numbers / signals match a 6525 while the schematics says "6523" which
seems like a bad copy.

If you are anyway going to change the construction, maybe you should
consider some dual port ram? Although probably both more expensive and
harder to get, it would be far nicer and probably faster too.

(In the long run, IMHO it would be best to make a replica B motherboard
with faster RAM and 8088 synced to the 6509 signals in a way that makes
it possible for both processors to access ram pseudo simultaneously.
Some time in a distant future...)


--
(\_/) Copy the bunny to your mails to help
(O.o) him achieve world domination.
(> <) Come join the dark side.
/_|_\ We have cookies.

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Re: 8088 card replica

vossi
Hi Mia,
you are able to exchange 6523 and 6525 if extended features of the 6525 like
IRQ not needed.
In the 1551 Floppy is a 6523 or a 6525...

I think in the 8088 board are both ok.

Christian



-----
greets
Christian
--
Sent from: http://cbm-hackers.2304266.n4.nabble.com/

greets
Christian
smf
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Re: 8088 card replica

smf
Yeah, the 6523 lacks the ability to use port C for handshaking and
(weird) interrupt priority.

http://archive.6502.org/datasheets/mos_6523_tpi_preliminary.pdf

http://archive.6502.org/datasheets/mos_6525_tpi_preliminary.pdf

On 26/03/2018 08:53, vossi wrote:
> Hi Mia,
> you are able to exchange 6523 and 6525 if extended features of the 6525 like
> IRQ not needed.
> In the 1551 Floppy is a 6523 or a 6525...
>
> I think in the 8088 board are both ok.
>
> Christian

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Re: 8088 card replica

Michał Pleban
In reply to this post by MiaM
Hello!

Mia Magnusson wrote:

> Btw the original schematics (CBM_8088_CPU_co-processor_schematic.pdf)
> is hard to read. Just to make sure, is it indeed an 6525? All pin
> numbers / signals match a 6525 while the schematics says "6523" which
> seems like a bad copy.

There is a 6525A in my board. But the board uses the chip only for I/O
pins, so I presume you can use either 6523 or 6525.

> If you are anyway going to change the construction, maybe you should
> consider some dual port ram? Although probably both more expensive and
> harder to get, it would be far nicer and probably faster too.

I was thinking about dual-port RAM to simulate video RAM, so that the
8088 could write to it simultaneously with 6509 reading from it and
copying to CBM-II video RAM. But this kind of setup might be complicated.

Regards,
Michau.