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Rapidus Accelerator (rev.1c) for Atari XL/XE

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The video was only published yesterday and it doesn't have any links.

The guy only has one other video and that's supposedly of a ZX Spectrum emulator running on an accelerated Atari.

There aren't any pictures of a prototype or any real hardware in either video.

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Thanks for the info all, it's good to see the author has uploaded more vids tonight. I would love to tick off an 816 upgrade from my all time wish list.

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I want some too... when will it be released ? Can someone tell me if this device has liniear memory support for the 65c816 and is there extra memory on the board ?

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Pretty amazing, but why does this upgrade look so complex if it's only a CPU?

 

Doesn't the 65C816 that comes in a 40 pin DIP close to a drop in replacement for Antic?

 

Is that a display connector on the board?

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Pretty amazing, but why does this upgrade look so complex if it's only a CPU?

 

Doesn't the 65C816 that comes in a 40 pin DIP close to a drop in replacement for Antic?

 

Is that a display connector on the board?

Antic? Where?

 

Partially guessing here but the board appears to have the 6502C CPU, 65816, FPGA, RAM, a JTAG connector, an expansion connector, other programmable devices(?), Cache RAM(?)...

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Looking at the SI* run, it looks like they have 16MB of linear 65816 DRAM and 256K of XE SRAM. The 6502 must be disabled after it boots, somehow.

 

DRAM usually takes a controller, so they need an FPGA or some such. I would guess that the 256K XE SRAM is shared with the 6502, half to the 65816 and half to the 6502.

 

The DRAM is usually 3v logic, so the 65816 is probably running at 3v.

 

Odd thing is that I don't see any connection to the MMU PAL. How can they see carts and $D301-type things? The MMU decides whether you go to memory or some I/O chip..?

 

Nice board!

 

Bob

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Hello Everyone

 

Well, I was not sure, if I should publish any data related to this project or wait few months more. I'm not used to show anything before it is really worth of that, but I decided to give you some details.

 

As you already know Rapidus Accelerator is the turbo card for Atari 8-bit machines. It is designed to be used in models with New Device feature support, so unmodified 400/800 and probably 1200XL won't work as it was intended, however, I'm not saying that it is not possible to use it with 400/800/1200XL machines. It has been never tested.

 

Installation inside the computer is quite simple. You have to put Rapidus board in place of removed 6502 and this 6502 you have to insert into socket on Rapidus card. Than you have to connect just 3 wires... or not, if you want to load the fpga core from external device. Compared with, for example VBXE, Rapidus doesn't have any additional microcontroller to load the core. This task belongs to 6502.

 

4835538400_1370378729.jpg

 

Of course every atari model has its own mechanical constrains, so in case of need additional adapter should be used then (with or without additional signal buffering). Design of adapters is in progress.

 

5806311300_1370379007.jpg

 

Rapidus is a quite complex device, because replacing only the old 6502 with new 65c816 won't allow you to increase the clock speed, use linear memory above the 64KB or do any usage of ABORT interrupt. You get wider instruction set and that's all.

 

The idea implemented in Rapidus was to separate fast 65c816 bus from relatively slow atari bus and use so called data bridge to exchange the information between those two "creatures". This is not easy, because the data bridge has to emulate all timings as original 6502 CPU has and control 65c816. The thing is complicating more, if we consider, that atari bus is controlled also by Antic. This is a main reason why to have cpld/fpga on the board. The next good reason is flexibility. FPGA can give you more features, than just few input/output registers. Clock multipliers, additional ram and rom without any additional waitstates generation and more. We should also remember, that new logic devices are not 5V tolerant, so voltage translators are more then welcome.

 

So, at the end we get:

- 65C816 CPU operating at 16MHz completely asynchronously to Atari bus, VCC at 5V (unlike the rev.1b where ~14MHz clock is used and 3.3V),

- 512kb or 1MB of zero waitstate SRAM,

- up to around 30.5MB of storage ram - SDRAM clocked 128MHz (14.5MB and 113MHz for rev.1b),

- 512kB of Flash memory (256kB is reserved for fpga cores, 256kB for OS and New Device handler)

- 256b of I2C EEPROM for settings (rev.1c only)

- and more features implemented inside the fpga, but I don't want to describe them now.

 

Regarding the connector. It is something like parallel bus and it's going to be used by daughter board called "Portus".

 

Project is not ready to be released. There are some things to be done in hardware, but more critical is software. A lot of code must be written first.

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So this should work in an XL-ised 1200XL (i.e. with XL OS and parallel bus)? In addition, is it likely to work alongside VBXE?

 

Yes, if your 1200XL has XL OS and MPD and ExtSel signals are available, Rapidus should work.

VBXE is fine. In one of my testing machines I have VBXE 1.0 and have no problems.

The stability issues may be observed if you have many HW expansions, where data and address lines are overloaded. Special adapter with signal buffering should help in this case.

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The project page has many interesting documents. I particularly like the part where they talk about [feature that wasn't discussed on Atari Age so I won't mention it].

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