The Atari Portfolio 2 prototype

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agranlund
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Re: The Atari Portfolio 2 prototype

Post by agranlund »

Wow, this is really interesting, thanks for sharing this :)
Walker75
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Re: The Atari Portfolio 2 prototype

Post by Walker75 »

Hi, I just stumbled over your finding and would love to see this one
included in Mame.

What I could not see - does this board have a similar expansion port like the original portfolio, or just the card reader?

If i find time I would love to fiddle around with the current mame portfolio device and try to adapt the driver to the screen size of this one.

Not sure if there are other notable changes on the hardware side, but from what I could gather with your dumped roms the
existing driver should be able to boot up and should be easy to adapt to a new screen size? (Work I should able to perform :) ... )
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derkom
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Re: The Atari Portfolio 2 prototype

Post by derkom »

Walker75 wrote: Fri Aug 26, 2022 8:42 pm What I could not see - does this board have a similar expansion port like the original portfolio, or just the card reader?
It does have an expansion port, but it's not the same physical connector:

p2-exp.jpeg
p2-exp.jpeg (75.3 KiB) Viewed 1734 times

The release version Portfolio has a 60-pin expansion connector. This connector is 50-pin. I have not made any attempt to compare this connector's function to the expansion port on the released Portfolio, but I would suspect it provides the same capabilities. I can check on this for you, but not for at least a few days.
Not sure if there are other notable changes on the hardware side, but from what I could gather with your dumped roms the
existing driver should be able to boot up and should be easy to adapt to a new screen size? (Work I should able to perform :) ... )
I would suspect so. The only other noteworthy change to the hardware is the prototype has two card slots (there's a second one under the ROMs). I have not been able to test both simultaneously, as I have only one card. :)

However, regarding those ROMs, after it came up in another thread that the EPROM in use here has /OE and A16 swapped relative to what my reader was expecting, I suspect that the dumps in the first post are incomplete. I was able to resolve the pin swap for writing out some (unrelated) ROMs by bending some pins and running a jumper, but I don't want to do that with these ROMs, lest I break off a pin.

I've been meaning to build a proper adapter and re-dump the ROMs, but just haven't gotten around to it. But now you've given me a good reason to accelerate that project! Again, though, I'll be indisposed for a few days before I can do anything about it.
Walker75
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Re: The Atari Portfolio 2 prototype

Post by Walker75 »

Take your time, I am more than happy with what you were able to share already.

From what learned from the mame forums is that there is always something hiding in plain sight for years which holds important bytes,
and these roms are really delicate to handle.

Best I can do is try to gather as much documentation from your findings and try to poke the correct people.

I feel like more clear pictures about the board so we can trace stuff around could be worthy,
the existing images you made are already great, but I believe a lot of the paths are not visible enough to trace.
Also more angles might be interesting.

BTW: What is the chip with the 10B9 Label to the right of the reset label in the board pictures?
x86vet
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Re: The Atari Portfolio 2 prototype

Post by x86vet »

@derkom, I am familiar with this BD board, and can answer questions about it. I've sent you a PM.

@Walker75, U21, 22 & 23 support the 82C425. U21 & U22 are 8 KB SRAMs used for the character codes and attribute codes, forming the 16 KB CGA display memory. U23 is probably a 2 KB (I think, could be up to 8 KB) ROM that contains the character font (each font uses up to 4 KB), for demo purposes. The label is probably a checksum.
Walker75
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Re: The Atari Portfolio 2 prototype

Post by Walker75 »

@x86vet
Thanks for that info, so for completeness their contents would be important as well for the mame driver

Do you know if their contents is visible to the cpu when the board is powered and at which memory location the contents would be?

So we could write a dumper tool .com file so these roms would not have to be unsocketed for readout?
x86vet
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Re: The Atari Portfolio 2 prototype

Post by x86vet »

I hadn't come across MAME before, which sounds interesting. Is there already a version for the Atari Portfolio?

Let me try and answer your questions:

This BD board is essentially the same as the Atari Portfolio hardware circuitry but with the Hitachi display controller and LCD row and column drivers (for MDA) replaced by a C&T 82C425 controller (for CGA) with its 3 storage devices (U21, 22 & 23). Plus the board has 512 KB of RAM and two memory card slots. The only real BIOS difference is support for CGA rather than MDA. Plus Setup screens to configure the controller via new Int 61h services.

The BD board BIOS configures the CGA controller for 8 scan lines per character row, with a single character font defined by 8 bytes (so a 256 character font requires 800h of storage). The 82C425 register usage is defined in its datasheet. The proptotype for this board had an SRAM to store font data, but this demo board appears to have the font in ROM. Either way, the font data can be accessed by the Function Control register 0DFh bit 1. The datasheet says:

"This bit controls access to the font RAM. When set to '1', the font RAM can be accessed by the CPU as the first 8Kbytes of the display buffer address space (B8000h - B9FFFh). When this bit is '0',access to the font RAM is disabled".

A .com file code snippet to access the font data is below. It assumes segments and flags are as on entry.

;Enable Font ROM

mov dx,3D4h ;Access Func control reg
mov al,0DFh
out dx,al

inc dx ;Advance to data reg
in al,dx ;Read current value
or al,02h ;Enable Font ROM
out dx,al

;Copy Font table from ROM to buffer

mov si,0B800h ;Access Video RAM
mov ds,si ; via DS:SI
xor si,si

mov di,offset buffer ;Assumes ES points to buffer segment (to capture the font data)

mov cx,800h ;This should be set to the ROM size, or it may wrap. The ROM has to be at least 2 kB. So start with 800h, to load the first 8x8 font table

rep movsb ;Copy to buffer

;Disable Font ROM

in al,dx ;Read data reg
and al,not 02h ;Disable Font ROM
out dx,al

Apologies if this is obvious. BTW, I don't know how to correct the formatting above, all whitespace is being stripped out.

The two 8 KB SRAMs are treated as the 16 KB CGA video RAM at 0B800:0h, and accessed as such by the BIOS via normal memory reads and writes. The C000 and E000 ROMs operate the same as on the Portfolio; the E000 ROM is permanently in context, the C000 ROM can be switched out but in normal operation it is in context.

Hope this helps.
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derkom
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Re: The Atari Portfolio 2 prototype

Post by derkom »

Walker75 wrote: Sun Aug 28, 2022 12:35 pm I feel like more clear pictures about the board so we can trace stuff around could be worthy,
the existing images you made are already great, but I believe a lot of the paths are not visible enough to trace.
I can certainly get you some better photos, with an eye to traceable traces. :)
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Cyprian
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Re: The Atari Portfolio 2 prototype

Post by Cyprian »

x86vet wrote: Sun Aug 28, 2022 1:46 pm @derkom, I am familiar with this BD board, and can answer questions about it. I've sent you a PM.
Can you tell more about that prototype? Where there any others? Why didn't it go into production?
Btw. I bought your book, it's cool a piece of history.
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http://260ste.atari.org
x86vet
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Re: The Atari Portfolio 2 prototype

Post by x86vet »

@Cyprian
In 1990 DIP was exploring ways to build on the IP it had developed. One logical next step was to create a version of the Portfolio with an 80x25 display, rather than its 40x8 one.

Displaying 80x25 text on a small palmtop screen wasn’t ideal, as it could be hard to read without a backlight. EL backlights used too much power, which would significantly reduce battery life.

(As a side note, both the Poquet PC and the Sharp PC-3000 suffered from this issue; DIP provided a way to increase the font size on the PC-3000 to try and address it - but with fewer rows displayed).

So DIP envisioned an 80x25 CGA version of the Portfolio, but with a big display (BD) that was more legible. An initial prototype was created that consisted of a development DIP Pocket PC (PPC) patch-wired to another circuit board with an 82C425 and support RAM that drove an LCD display. This prototype hardware was used to test a CGA variant of the Portfolio BIOS that had been developed in parallel. At the time greyscale CGA was leading edge, this was the era before colour LCDs were mainstream.

The prototype was shown to Atari, who wanted to explore the concept further. So a demo system (there may have been more than one) was created as a tablet design using a single PCB - the subject of this thread - that Atari product execs could play around with.

Atari decided not to take the concept forwards. I don't know the exact reason why, however there were issues with the Portfolio. The hardware was not fully PC compatible, which caused a growing number of DOS programs to get stuck in a loop polling (unimplemented) keyboard port 60h for a key press. Also, the 4.9 MHz 80C88 was relatively underpowered by late 1990, and the built-in applications were slow when handling more than a few hundred bytes of stored data.

As you will know from reading my book - thank you! - around this time DIP also developed a couple of variants of the Portfolio. A financial “Expert” calculator for a company based in the south of France, and a handheld scanner type system for a company based in Italy. These were "Portfolio 2" type systems that used an enhanced version of the PPC ASIC. Fully working prototypes were created for both customers, but neither progressed to commercial production.

DIP was then approached by Sharp Corporation to develop the Sharp PC-3000. While this was not a Portfolio 2 (it used a completely different ASIC with full PC I/O port compatibility), many of the concepts developed for the Portfolio - such as memory card emulation of disks and power management - were leveraged in the PC-3000.
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