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Van

Member Since 24 Mar 2011
OFFLINE Last Active Sep 18 2017 3:08 PM

Posts I've Made

In Topic: 1088XEL Alternative Mother-Board Project

Sat Sep 2, 2017 3:50 PM

I have tested TurboFreezer 2011 and it works fine. However, the cart and eci ports really need to be extended elsewhere to make it useful. The TF switches are underneath as you can see in the picture.attachicon.gif20170902_173411.jpg

Could maybe use RA connectors, ala XE. Not sure where to source the connectors, considering the straight connectors seem kind of rare.

Yogi


In Topic: 1088XEL Alternative Mother-Board Project

Sat Sep 2, 2017 3:34 PM

Note - if you turn off ANTIC DMA, I have managed to get 88k/sec from a CF based PBI device, under SDX.

Oh good point. In fact I had been considering this during playback, but most people want to see something and it helps during debugging. Running headless is done often with chipmusic setups for better timing.

Yogi


In Topic: 1088XEL Alternative Mother-Board Project

Sat Sep 2, 2017 1:49 PM

Thanks Michael. I think I found a ball park comparison for loading speeds of different media

http://atariage.com/...sion/?p=3747446

Standard SIO - 1.5K/sec

HS SIO - 5K/sec

PBI HDD - 50K/sec

So if these are close to reality, I should be fine loading from CF to Ext RAM banks :)

Yogi


In Topic: Atari 8 memory maps?

Sat Sep 2, 2017 12:12 PM

PDF scans of lots of A8 books:  http://www.atarimani...-books_1_8.html

Yogi


In Topic: 1088XEL Alternative Mother-Board Project

Sat Sep 2, 2017 10:50 AM


Note: Since the XEL-CF creates a fast parallel IDE44 interface, there is very little reason to use an SIO2SD or any other similar CF/HDD solution. Especially considering that I just bought 20 bare PCB's for close to $1 a piece, and the components to stuff it probably are in the area of $5. Since it is a Through-Hole board, it is very easy for the DIY person to build, and due to the limited amount of parts required to do so a relatively quick job. With Jon's XEL-CF specific BIOS flashed into the U1MB, it is the same as accessing a CF card on a SIDE2, and just as fast. Theoretically any IDE device could be accessed, assuming a supporting BIOS for such were in use. The IDE44 header is directly compatible hardware-wise with 2.5" laptop hard drives, and a 2 mm to 0.1" header adapter with a suitable PSU could be employed to access larger devices.

 

- Michael

Let me ask you Michael, or anyone, about the CF HDD speed? I'm debating the best handling of a large DRO music file, either direct from CF or pre-loaded into ext RAM. Banking the whole file is the fastest access at runtime, but the down side is the load time but that would be before play back starts. So for a 50-100k file, SIO based media seems prohibitive for pre-loading the RAM banks. Transferring from CF to ext RAM seems like it would cut the load time but if the CF access time is fast enough would rather buffer small blocks during runtime direct from the CF.

 

Background:

A DRO file is a log of register writes to an OPL chip. Each entry in the log are two bytes composing either the register number and value or command and value. The commands are delays, either 1mS or 256mS x Value+1. So during play back the main loop could be handling back to back register writes or register writes inter-spread with delays. Over all song timing depends on (register writes + delays commands)+loop/system overhead.

Yogi